High yield microbes – Flashcards
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| Streptococcus pyogenes |
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| Gram positive cocci in chains, catalase negative. Beta hemolytic, bacitracin sensitive and pyrrolidonyl arylamidase (PYR) positive. Transmitted by direct contact and respiratory droplets. M protein associated with acute glomerulonephrits. Also contains several spreading factors including exotoxins A-C which cause pyrogenesis and erythrogenesis. Can cause pharyngitis, rheumatic fever (post infection), scarlet fever and pyroderma/impetigo. |
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| Streptococcus agalactiae |
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| Gram positive cocci in chains, catalase negative. Beta hemolytic and bacitracin resistant. Can hydrolyze hippurate and is CAMP test positive. Bacitracin resistant. Reservour in the human vagina and GI and can be transmitted to newborns (prolonged labor after rupture of membranes). |
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| Streptococcus pneumoniae |
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| Gram positive cocci, catalase negative. Alpha hemolytic, optochin sensitive, lancet shaped diplococci and lysed by bile. Reservoir in upper respiratory tract. Capsule makes it dangerous in asplenic patients and causes a positive Quellung reaction. Most common cause of typical pneumonia especially in pts. in their 60s. Also the most common cause of adult meningitis. |
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| Viridans streptococci (S. sanguis, S. mutans) |
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| Gram positive cocci in chains, catalase negative. alpha hemolytic and optochin resistant. Normal flora of the human oropharynx. Biofilm makes it dangerous for damaged heart valves (subacute endocarditis) and for dental caries. |
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| Enterococcus faecalis/faecium |
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| Catalase negative PYR+. Group D gram positive cocci in chains. Can hydrolyze esculin in 40% bile and 6.5 NaCl. Common cause of urinary and biliary tract infections. Can cause subacute endocarditis in the elderly due to damaged heart valves. |
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| Bacillus anthracis |
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| Gram positive rod that can form spores. Aerobic. Large boxcar-like appearance. Toxin contains a protective antigen, lethal factor and edema factor. Can give a toxoid vaccine for high risk individuals. |
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| Bacillus cereus |
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| Gram positive rod that can form spores. Aerobic. Found in nature. Associated with food that is kept warm, not hot. Has an emetic preformed toxin associated with fried rise and a diarrheal toxin (watery diarrhea). |
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| Clostridium tetani |
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| Gram positive spore forming rod that is anaerobic. Has a "tennis racket" appearance under the microscope. Toxin formed binds to ganglioside receptors and blocks the release of glycine and GABA at spinal synapses, causing extreme muscle spasm. Organism is rarely isolated. |
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| Clostridium botulinum |
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| Gram positive spore forming rod that is anaerobic. Reservoir is dirt and dust. Can be transmitted via food or via traumatic transplantation. Toxin is an A-B polypeptide neurotoxin that is highly toxic and heat liabile. Blocks the release of acetylcholine at the myoneuronal junction resulting in flaccid paralysis. Can be a problem for canned foods or in children that ingest honey. |
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| Clostridium perfringes |
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| Gram positive spore forming rod that is anaerobic. Stormy fermentation in milk media. Double zone of hemolysis. Foodborne and traumatic implantation. Identified by the Nagler reaction (egg yolk agar plate with one side having anti alpha toxin. Detect lecithinase activity.) Can cause gas gangrene and food poisoning. |
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| Clostridium difficile |
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| Gram positive spore forming rod that is anaerobic. Has toxin A and B which damage the mucosa leading to fluid increase and lead to cytopathology, respectively. Cause of pseudomembranous colitis. DOC is metronidazole. |
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| Listeria monocytogenes |
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| Gram positive non-spore forming rod that is facultative intracellular. Exhibits tumbling motility. Can grow in the cold of the refrigerator in soft cheeses and hot dogs. Can cause severe neonatal disease (Early=granulomatosis infantisepticum, late can cause meningitis with septicemia from fecal exposure). MCC of meningitis in renal transplant patients and adults with cancer. |
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| Cornebacterium diphtheriae |
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| Gram positive rod that is non-spore forming. aerobic. Club shaped. Not invasive, the toxin causes an inhibition of protein synthesis by adding ADP-ribose to eEF-2. Causes the appearance of a dirty gray pseudomembrane and can cause recurrent laryngeal nerve palsy and lower limb polyneuritis. |
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| Actinomyces israelii |
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| Anaerobic gram positive branching rod that is non-acid fast. Normal flora of gingival crevices and in the female genital tract. Disease causes "sulfur" granules in exudate that can be uesd for microscopy or culture. Only in tissues with low oxygenation. Also, can cause a solitary brain abscess, NOT multiple abscesses. |
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| Nocardia asteroides, nocardia brasiliensis |
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| Gram positive branching rod that is aerobic and partially acid fast. Found in soil and dust. Can cause MULTIPLE brain abscesses if it spreads to CNS. No toxins or virulence factors are known. |
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| Mycobacterium tuberculosis |
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| Acid fast rods that are obligate aerobes. Contains mycolic acids highly resistant to desiccation and many chemials including NaOH. Appears fluorescent apple green with auramine-rhodamine staining. Prodases a heat sensitive catalase active at body temp. Facultative intracellular organism that can produce sulfatides, chord factor, and a surface protein that can cause delayed hypersensitivity and cell mediated immunity. Causes the formation of a Ghon complex. |
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| M avium intracellulare |
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| Acid fast rods that are obligate aerobes. Contains mycolic acids highly resistant to desiccation and many chemials including NaOH. Causes pulmonary, GI and disseminated disease. Presents in AIDS patients, cancer patients, and those with chronic lung disease. Nonchromogen. Treat AIDS patients prophylactically for this with a CD4 of less than 50. Macrolide plus ethambutol. |
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| M. Kanasasii |
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| Acid fast rods that are obligate aerobes. Contains mycolic acids highly resistant to desiccation and many chemials including NaOH. Causes pulmonary, GI and disseminated disease. Presents in AIDS patients, cancer patients, and those with chronic lung disease. Photochromogen. Treat AIDS patients prophylactically for this with a CD4 of less than 50. Macrolide plus ethambutol. |
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| M. scrofulaceum |
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| Acid fast rods that are obligate aerobes. Contains mycolic acids highly resistant to desiccation and many chemials including NaOH. Can cause lymphadenitis. Transmitted via contaminated water sources. Presents as solitary cervical lymphadenopathy in children. Scotochromogen. Treat with surgery. |
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| M. Marinum |
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| Acid fast rods that are obligate aerobes. Contains mycolic acids highly resistant to desiccation and many chemials including NaOH. Soft tissue infections, "fish tank granuloma) transmitted via abrasions. Presents in tropical fish enthusiasts. Photochromogen. Treat wit hINH, rifampin or ethambutol. |
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| Mycobacterium leprae |
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| Acid fast rods that are obligate aerobes. Contains mycolic acids highly resistant to desiccation and many chemials including NaOH. Causes Hansen's disease. Found via punch biopsy. Optimal growth at less than body temperature. Transmitted via nasal discharge in untreated patients. Can have a strong CMI response or weak CMI; the former being more desirable. Give dapsone for close family contacts to prevent spread. |
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| Neisseria meningitidis |
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| Gram negative diplococci with flattened sides. Oxidase positive. Particularly kidney bean shaped. Large capsule that can be picked up via latex particle agglutination. Grows on chocolate agar and ferments maltose. Can cause meningitis and Waterhouse-Friderichsen syndrome. Common in young adults with meningitis. |
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| neissera gonorrhoeae |
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| Gram negative diplococci with flattened sides. Oxidase positive. reservoir is the human genital tract. Sensitive to drying and cold. Uses pili to attach to mucosal surfaces and has widely varying antigens. Disease presents as urethritis, proctitis, endocervicitis, PID, arthritis, procititis, and ophthalmia and rapid blindness when in newborns. Culture on Thayer-Martin medium (selects for pathogenic strains). |
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| Moraxella catarrhalis |
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| Gram negative diplococcus that is a normal upper respiratory tract flora. Most common cause of Otitis media and sinusitis. Most strains produce a beta lactamase. |
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| Pseudomonas aeruginosa |
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| Gram negative rod that is oxidase positive. Aerobic (non-fermenting). pyocyanin pigment (blue-gree) and fluorescein expression. Can present with a grape-like odor on culture and has a slime layer. Has non-lactose fermenting colonies on EMB or MacConkey agar. Umiquitous in water. Exotoxin ADP ribosylates eEF-2, inhibiting protein synthesis and the liver is the primary target. Can cause hot tub folliculitis, eye ulcers, and cellulitis in burn patients (blue-green puss). Can be a major problem as a cause of typical pneumonia in patients with CGD or CF. |
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| Legionella pneumophila |
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| Weakly gram negative organism that usually needs a flurescent AB test to be visualized. Requires cysteine and iron for growth in media. No human to human transition; water organism. Facultative intracellular (granulomatous response). Common problem in smokers over age 55 with high alcohol intake and in immunosuppressed patients (renal transplant patients). Associated diseases are common due to air-conditioning systems that are unclean. |
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| Grancisella tularensis |
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| Gram negative small rod organism that is a facultative intracellular pathogen. Can cause "rabbit fever" as a zoonist. Can be transmitted via dermacentor tick bites, traumatic implantation, aerosols, and via ingestion. Treat with streptomycin. |
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| Bordetella pertussis |
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| Gram negative small rods that are strict aerobes. Encapsulated. Attaches to nasopharyngeal ciliated epithelial cells via filamentous hemagglutinin. Toxin also aids in attachment. Toxin causes lymphocytosis promotion, islet activation (can cause hypoglycemia), immune cell effector blockage, and increased histamine sensitivity. Organism causes whooping cough, and is easiest to diagnose in the Catarrhal stage (1-2 weeks) even though this stage does not have the typical cough. The paroxysmal stage has the typical symptoms, but harder to find the organism in this stage. Vaccination is protective. |
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| Brucella abortus (cattle), melitensis (goats), and suis (pigs) |
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| Gram negative rod that is aerobic. Zoonosis. Facultative intracellular pathogen that is a potential biowarfare agent. Causes an undulant fever (rises and falls) usually when drinking unpasteurized milk or via work in a slaughterhouse. |
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| Campylobacter jejuni |
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| Gram negative curved rods with polar flagella. Looks like "gull's wings". Oxidase positive. Microaerophilic, and grows well at 42 degrees C. Need as few as 500 organisms to be infectious. Causes gastroenteritis with possibly 10 or more frankly bloody stools per day. Can be a cause of Guillain Bare syndrome (serotype O:19. Treatment is mostly supportive. |
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| Helicobacter pylori |
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| Spiral shaped gram negative bacilli with flagella. Urease positive. Causes chronic gastritis and duodenal ulcers. |
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| Vibrio cholerae |
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| Gram negative curved rod with polar flagella. Oxidase positive and can grow on alkaline media (TCBS medium). Shooting star motility. Fecal oral spread (sensitive to acid). Enterotoxin that ADP ribosylates Gs alpha, causing eflux of Cl and water. Rice water stools. |
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| Vibrio parahaemolyticus |
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| Gram negative curved rod with polar flagella. Oxidase positive and can grow on alkaline media (TCBS medium). Transmitted through undercooked seafood. Causes self-limited gastroenteritis. |
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| Vibrio vulnificus |
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| Gram negative curved rod with polar flagella. Oxidase positive and can grow on alkaline media (TCBS medium). Spread through swimming in brackish water or via consumption of raw seafood (particularly oysters). Can cause gastroenteritis and cellulitis based on innoculation site. Dificult to treat if cellulitis; can require amputation. |
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| enterotoxogenic Escherichia coli (ETEC) |
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| Gram negative rod that is a facultative anaerobe. Ferments glucose and lactose and is cytochrome C oxidase negative. Can reduse nitrates to nitrites. Catalase positive, oxidase negative. Can cause recurrent infections in patients with CGD. Most common cause of UTIs and the second most common cause of neonatal meningitis. Has a heat labile toxin that stimulates adenylate cyclase, and a heat stable toxin that stimulated guanylate cyclase. Causes non-inflammatory diarrhea. Rehydrate. |
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| Enteropathogenic E. Coli. (EPEC) |
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| Gram negative rod that is a facultative anaerobe. Ferments glucose and lactose and is cytochrome C oxidase negative. Can reduse nitrates to nitrites. Catalase positive, oxidase negative. Can cause recurrent infections in patients with CGD. Most common cause of UTIs and the second most common cause of neonatal meningitis. Causes noninflammatory diarrhea in babies of developing countries. Adheres to M cells. |
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| Enteroinvasive E. Coli (EIEC) |
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| Gram negative rod that is a facultative anaerobe. Ferments glucose and lactose and is cytochrome C oxidase negative. Can reduse nitrates to nitrites. Catalase positive, oxidase negative. Can cause recurrent infections in patients with CGD. Most common cause of UTIs and the second most common cause of neonatal meningitis. Invades the large bowel and causes inflammatory diarrhea (blood, pus, fever, abdominal pain). Can form actin jet trails. |
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| Enterohemorrhagic E. Coli (EHEC) |
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| Gram negative rod that is a facultative anaerobe. Ferments glucose and lactose and is cytochrome C oxidase negative. Can reduse nitrates to nitrites. Catalase positive, oxidase negative. Can cause recurrent infections in patients with CGD. Most common cause of UTIs and the second most common cause of neonatal meningitis. Verotoxin producer which decreases protein synthesis by interfering with the 60S ribosomal subunit. NOT invasive. Antibiotics will increase the risk of HUS. |
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| Klebsiella pneumoniaae |
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| Gram negative rods that have a capsule. Causes the creation of a currant-jelly sputum. Can cause UTIs in association with catheters. Oxidase negative and forms mucoid, lactose fermenting colonies on MacConkey agar. Endotoxin causes septicemia. Pneumonia of those who are alcoholics. |
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| Shigella sonnei, flexneri, dysenteriae, boydii |
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| Gram negative rod that is a non-lactose fermenter. Non-motile. Spread via the fecal oral route. INvades M cells and very shallow ulcers form. Toxin is neurotoxic, cytotoxic, and enterotoxic. Clips the ribisomal 60S subunit. Disease characterized by a high fever (>101F), lower abdominal cramps, tenesmus, diarrhea (watery progressing to bloody). Severity depends on the patients age and on the strain. |
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| Yersinia pestis |
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| Gram negative rod that bipolar stains. Facultative intracellular parasite and is coaglase positive. Spread by fleas that vomit up the organism due to coagulase. Can be spread via fleas or via respiratory droplets. Causes bubonic plague or pneumonic plague. |
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| Yersinia enterocolitica |
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| Motile gram negative rod at 25C, but non motile at body temperature. Cold growth. Transmitted in unpasturized milk and in pork. Prominent in northern climates. Causes enterocolitis as pseudoappendicitis in kids and young adults and can cause reactive arthritis in adults. |
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| Proteus mirabilis, vulgaris |
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| Gram negative rod that has peritrichous flagella. EXTREMELY motile. Non lactose fermenting and urease positive. Facultative anaerobe, oxidase negative. Can cause staghorn renal calculi (flank pain). Can cause UTIs. |
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| Salmonella typhi |
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| Gram negative rods that are non lactose fermenter. Produses H2S and is sensitive to acid. No animal reservoirs. Organism resides in the gall bladder. Can resist macrophage killing. Symptoms of disease include FEVER, headache, abd. pain, constipation (more common than diarrhea) and can lead to necrosis of peyer patches if left untreated. Thrombophlebitis, cholecystitis, pneumonia, absess formation, etc. |
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| Salmonella enteritidis, typhimurium |
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| Facultative gram negative rod, non lactose fermenting on EMB or MacConkey medium. Motile and produces H2S. Can detect antibodies in serum via the Widal test. Transmitted largely through chicken products and reptile pets. Needs a large innoculation dosage due to acid sensitivity (>10^5). Sickle cell disease with this infection predisposes to osteomyelitis. MCC in these patients.Culture on Hektoen agar (black colonies). |
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| Haemophilus influenzae |
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| Gram negative pleomorphic rod. Requires growth factors X and V for growth on nutrient or blood agar. Has a polysaccharide capsule. Causes meningitis commonly in unvaccinated children aged 3 months to 2 years. Can cause bronchitis, pneumonia and epiglottitis in unvaccinated toddlers (children present with "catcher's stance" to aid in breathing). |
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| Haemophilus ducreyi |
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| Gram negative pleomorphic rod. Requires growth factors X and V for growth on nutrient or blood agar. Has a polysaccharide capsule. Reservoir in human genitals and causes very painful soft chancres. |
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| Gardnerella vaginalis |
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| Gram-variable rod that is a facultative anaerobe. Causes a strong vaginal odor and increased discharge (thin, gray fluid). Clue cells can be seen on saline vaginal smears. Whiff test positive. |
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| Pasturella multocida |
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| Small gram negative rod that is facultative anaerobic. Reservoir in the mouths of many animals especially cats and dogs. Causes cellulitis with lymphadenitis. |
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| Eikenella corrodens |
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| Gram negative rod that "corrodes" agar when cultured. Bleach like odor. Transmitted by human bites or with fist fight injuries. Causes cellulitis. |
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| Capnocytophaga canimorsus |
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| Gram negative filamentous rod commonly spread by dog bites. Can cause overwhelming sepsis in spleenectomized patients. |
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| Bartonella henselae |
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| Gram negative rod that is the causative agent of cat scratch fever (bacillary angiomatosis in AIDS patients). |
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| Bacteroides fragilis |
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| Gram negative rod that is anaerobic. Expresses a modified form of LPS that is less active. Capsule is antiphagocytic. Can cause septicemia, peritonitis and abdominal abscesses. |
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| Treponema pallidum |
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| Thin spirochete gram negative organism not reliably seen on gram stain. Axial filaments with endoflagella. Serodiagnosis; cannot culture. obligate pathogen, but not obligate intracellular. Transmitted sexually or across the placenta to cause syphilis. Just after abx. treatment, this organism cancause Jarisch-Herxheimer reaction due to LPS release with dieing organisms. |
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| Borrelia burgdorferi |
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| Large spirochete that is gram negative and microaerophilic. Difficult to culture. Spread by Ixodes scapularis in the northeast and Ixodes pacificus on the west cost. Incidence is highest in the late spring and early summer. Can cause arthritis by type III hypersensitivity. Lyme disease. DOC is doxycycline. |
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| Leptospira interrogans |
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| Thin spirochete with hooks. Too thin to visualize. Gram negative. Seen on dark field microscopy, but not light microscopy. Aerobic. Transmitted by contct with animal urine in water. No toxins or virulence factors known. Causes an influenza like disease with or without GI symptoms (Weil disease). |
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| Chlamydia trachomatis |
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| Obligate intracellular bacteria with elementary bodies or reticulate bodies seen. Not seen on gram stain and cannot make its own ATP. Cell wall lacks muramic acid. Transmitted via sexual contact and at birth; also transmitted by hand to eye contact and flies in developing countries (leading cause of preventable blindness worldwide; causes inturned eyelashes!). STD in USA. White vaginal discharge. |
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| Chlamydia pneumoniae |
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| Obligate intracellular bacteria with elementary bodies or reticulate bodies seen. Not seen on gram stain and cannot make its own ATP. Cell wall lacks muramic acid. Potentially associated with atherosclerosis. Transmitted via resp. droplets. Causes walking pneumonia. |
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| Chlamydia psittaci |
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| Obligate intracellular bacteria with elementary bodies or reticulate bodies seen. Not seen on gram stain and cannot make its own ATP. Cell wall lacks muramic acid. Reservoir in birds (esp. parrots) and spread via the dust of dried bird feces. Causes an atypical pneumonia with hepatitis. If cough is present, the sputum is mucopurulent. |
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| Rickettsia rickettsii |
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| Aerobic gram negative bacilli that is an obligate intracellular bacteria. Doesn't make enough ATP to sustain itself. Transmitted via the hard tick (Dermacentor) and invades the endothelial cells of capillaries causing vasculitis in many organs (Rocky Mountain spotted Fever). Prevalant on east cost with a rash that starts (by 6th day) on the ankles and wrists that spreads to the trunk, palms, soles and face (centripetal rash). Used to be diagnosed using the Weil-Felix test (cross react antigens with ox strains of proteus vulgaris). DOC is doxycycline. |
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| Ehrlichia chaffeensis, phagocytophila |
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| Gram negative bacilli that is an obligate intracelluar bacteria of mononuclear or granulocytic phagocytes. Disease is similar to RMSF but withou a rash. Can cause leukopenia, thrombicytopenia, and mulberry-like structures inside of infected cells (morulae). |
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| Mycoplasma pneumoniae |
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| Smallest free living extracellular bacteria; has no peptidoglycan cell wall! Sterols in its membrane and requires cholesterol for culture. "Fried egg" colonies. Attaches to respiratory epithelium via P1 protein and inhibits ciliary action. Then produces hydrogen peroxide, superoxide radicals, and cytolytic enzymes which damage the respiratory epithelium. Causes walking pneumonia (most common atypical pneumonia). Functions itself as a superantigen. Causes mulberry-shaped colonies on sterol containing media. Positive cold agglutinins can be a clue but is not diagnostic. |
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| Ureaplasma urealyticum |
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| Smallest free living extracellular bacteria; has no peptidoglycan cell wall! Sterols in its membrane and requires cholesterol for culture. "Fried egg" colonies. Urease positive and can cause rethritis, prostatitis and renal caculi. Becomes part of normal flora when sexually active. If in children, this could indicate sexual abuse. |
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| Hepatitis A |
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| Infectious picornavirus featuring RNA and a naked capsid. Disease is mildly acute with no chronicity and with very low mortality. Diagnosis is with serospecific IgM. |
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| Hepatitis B |
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| Serum spread hepadnavirus featuring DNA and an envelope. Transmitted parenterally or sexually and can have a chronic form in 5-10% of those infected. Can cause primary hepatocellular carcinoma and cirrhosis. Low mortality. Vaccinated individuals express only HBsAb. |
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| Hepatitis C |
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| Post transfusion flavivirus featuring RNA and an envelope. Transmitted parenterally and sexually and 80% of those infected become chronic. Can cause primary hepatocellular carcinoma and cirrhosis. |
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| Hepatitis D |
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| Defective virus that requires a co-infection. Spread parenterally and sexually. Co-infection with a specific other agent can be occasionally severe, while superinfection is more often severe. Can cause cirrhosis and fulminant hepatitis. |
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| Hepatitis E |
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| Enteric hepevirus that features RNA and is a naked capsid. Transmitted fecal orally and can cause severe disease in pregnant patients with up to 25% mortality in the 3rd trimester. |
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| B19 virus |
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| Parovirus found in the human respiratory tract. SSDNA naked icosahedral virus. can be spread by fomites. Infects immature erythroid progenator cells, causing cell lysis. Results in anemia and is only clinically significant in sickle cell patients causing aplastic crisis. Can cause fifth disease, erythma infectiosum, and slapped cheek fever in children or adults. Can be a problem even in children that are "up to date on their vaccionations". |
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| Human papilloma virus |
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| Papillomavirus displaying circular dsDNA. Naked, icosahdral. Over 75 serotypes, but there are a number of very dangerous strains. Forms "warts". E6 and E7 inhibit p53 and Rb, respectively possibly leading to malignancy. over 90% of genital warts are serotypes 6 and 11, while,95% of cervical intraepithelia neoplasias contain HPV DNA. Koilocytic cells are characteristic. |
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| BK virus |
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| Polyomavirus (naked DNA vius) that is transmitted via respiratory droplets. Causes latent infection in renal cells and can cause renal disease in AIDS patients. |
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| JC virus |
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| Polyomavirus (naked DNA vius) that is transmitted via respiratory droplets. Infects oligodendrocytes causing demyelination. This can lead to progressive multifocal leukoencephalopathy in AIDS and transplant patients. |
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| Adenovirus |
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| dsDNA nonenveloped virus that is umbiquitous in humans and animals. Causes acute respiratory disease (ARD) and pneumonia primarily in the spring and winter. Can also cause pharyngoconjunctivits (pink eye), acute hemorrhgic cystitis (boys age 5-15), and gastroenteritis (less commonly than rotavirus or norwalk virus). Vaccine is live, nonattenuated used in te military. |
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| HSV-1 |
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| Large dsDNA enveloped icosahedral virus. Forms intranuclear inclusion bodies and can establish latency. Infections generally occur above the waist. Can cause serious meningoencephalitis. |
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| HSV-2 |
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| Large dsDNA enveloped icosahedral virus. Forms intranuclear inclusion bodies and can establish latency. Infections generally occur below the waist. Can cause mild meningoencephalitis. |
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| Varicella Zoster virus |
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| Large dsDNA enveloped icosahedral virus. Forms intranuclear inclusion bodies and can establish latency. Transmitted via respiratory droplets, causing chickenpox (asynchronous rash) and later shingles with immunocompromise. Diagnosis with a Tzanck smear (see intranuclear inclusions). Treat with acyclovir; asprin contraindicated in children with chickenpox (Reye's syndrome). |
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| Epstein Barr virus |
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| Large dsDNA enveloped icosahedral virus. Forms intranuclear inclusion bodies and can establish latency. 90% of the adult population is seropositive. Infects nasopharyngeal cells, salivary and lymphoid tissues and forms a latent B cell infection (bind CD21). Causes production of atypical reactive T cells (Downey cells). Causes heterophile positive mononucleosis (kissing disease). Can also lead to Burkitt lymphoma, nasopharyngeal carcinoma, and Hodgkin lymphoma. |
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| Cytomegalovirus |
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| Large dsDNA enveloped icosahedral virus. Forms intranuclear inclusion bodies and can establish latency. Establishes a persistent infection in fibroblasts, epithelial cells and macrophages. Latency forms in mononuclear cells. Classically characterized in infants as thrombocytic purpura "blueberry muffin baby". along with jaundice and hepatosplenomegaly. Can also cause heterophile negative mononucleosis in children and adults. |
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| HHV-6 |
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| Large dsDNA enveloped icosahedral virus. Forms intranuclear inclusion bodies and can establish latency. Replicates in peripheral blood mononuclear cells causing roseola (exanthema subitum) characterized by a fever lasting for 3-5 days followed by a lacy body rash. EXTREMELY high fever and risks febrile seizures. First fever, then rash. |
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| HHV-8 |
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| Large dsDNA enveloped icosahedral virus. Forms intranuclear inclusion bodies and can establish latency. reservoir in humans and can turn on VEGF, playing a role in deveoping Kaposi sarcoma. Need to differentiate from bacillary angiomatosis in AIDS patients. |
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| Variola/Smallpox |
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| Large DS DNA enveloped virus with complex morphology. Replicates in the cytoplasm and is a potential biowarfare agent. Disease has a 5-17 day incubation with a prodrome of flu like illness of 2-4 days. All vesicles are in the same stage of deveolment and Guarnieri bodies are found in the inefcted cells. 50% mortality. Disease is considered extinct. |
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| Molluscum contagiosum |
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| Large DS DNA enveloped virus with complex morphology. Replicates in the cytoplasm and is a potential biowarfare agent. Replicates in the dermis and causes wart like tumors to form. Eosinophilic cytoplasmic inclusion bodies can be seen in infected cells. self limiting in healthy individuals. |
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| Norwalk virus |
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| Calicivirus with positive sense ss-RNA. Naked and icosahedral. Causes watery diarrhea and can be a major problem on cruise ships. |
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| Poliovirus |
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| piconaviridae enterovirus with positive sense ssRNA. Small, naked and icosahedal. Summer and fall peak incidence. DOESNT cause diarrhea and has a peak age group of less than 9. Stable at low pH. Targets anterior horn motor neurons and causes paralysis. Salk vaccination is used today. |
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| Rhinovirus |
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| piconaviridae with positive sense ssRNA. Small, naked and icosahedal. Summer and fall peak incidence. Not stable under acidic conditions and grows at 33C. Causes most head colds. |
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| Coxsackie A virus |
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| piconaviridae enterovirus with positive sense ssRNA. Small, naked and icosahedal. Summer and fall peak incidence. DOESNT cause diarrhea and has a peak age group of less than 9. Stable at low pH. Fecal oral spread with potential for dissemination. Causes hand foot and mout disease (A16 strain), aseptic meningits, acute lymphoglandular pharyngitis and the common cold. |
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| Coxsackie B virus |
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| piconaviridae enterovirus with positive sense ssRNA. Small, naked and icosahedal. Summer and fall peak incidence. DOESNT cause diarrhea and has a peak age group of less than 9. Stable at low pH. Spread by fecal oral route. Causes Bornholm disease (Devil's grip) which is characterized by severe intercostal pain and fever. Can cause severe systemic disease of the newborn and myocarditis. |
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| Echoviruses |
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| piconaviridae enterovirus with positive sense ssRNA. Small, naked and icosahedal. Summer and fall peak incidence. DOESNT cause diarrhea and has a peak age group of less than 9. Stable at low pH. Fecal oral transmission and can cause fever and rash of unknown origin. Also can cause aseptic meningitis. |
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| St. Louis encephalitis virus (SLE) |
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| Flavivirus that is enveloped and icosahedral. Positive sense ssRNA and arthropod borne (arbovirus). Spread by the Culex mosquito and has a host of birds. Causes encephalitis. |
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| West Nile encephalitis virus |
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| Flavivirus that is enveloped and icosahedral. Positive sense ssRNA and arthropod borne (arbovirus). Spread by the Culex mosquito and has a bird host that is killed by the virus. Causes encephalitis. |
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| Dengue virus |
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| Flavivirus that is enveloped and icosahedral. Positive sense ssRNA and arthropod borne (arbovirus). Spread by the Aedes mosquito and its host is humans and monkeys. Causes break bone fever and reinfection can result in hemorrhagic shock with high mortality in children. |
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| Yellow fever virus |
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| Flavivirus that is enveloped and icosahedral. Positive sense ssRNA and arthropod borne (arbovirus). Spread b the Aedes mosquito and its host is humans and monkeys. Causes a type of fever characterized by liver, kidney, heart and GI (black vomit) damage. |
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| Rubivirus |
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| Togavirus that has ssRNA and is enveloped and is icosahedral. Can cause german measles (rash starts on the face and progresses to the torso; generally called 3 day measles). Can cause cateracts and deafness neonatally. |
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| Coronavirus |
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| Enveloped helical positive sense ssRNA virus. Causes severe acute respiratory syndrome (SARS). Fever of greater than 100F, flu-like illness, dry cough, dyspnea and progressive hypoxia. |
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| Human T cell leukemia/lymphotropic virus (HTLV) |
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| Positive sense ssRNA retrovirus that is enveloped. Can cause adult T-cell leukemia and expresses C-type particle. |
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| Human immunodeficiency virus (HIV) |
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| Positive sense ssRNA retrovirus that is enveloped. Commonly seen in homosexual males and IV drug users. CD4 count progressively declines as the immune system deteriorates. |
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| Measles virus |
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| Enveloped, helical nucleocapsid virus with negative sense ssRNA. Has a single serotype and has H glycoprotein and fusion protein; no neuraminidase. Causes the creation of giant cells and can escape immune detection by causing cells to fuse. Presents with the 3 C's (cough, coryza and conjunctivitis) and Koplik spots. Can also cause subacute sclerosing panencephalitis as a rare late complication. |
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| Mumps virus |
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| Enveloped, helical nucleocapsid virus with negative sense ssRNA. Single HN glycoprotein and F protein. Spread via respiratory droplets. Causes bilarteral parotitis with fever, headache, and malaise. Can cause pancreatitis, orchitis, and meningioencephalitis. |
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| Parainfulenza virus |
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| Enveloped, helical nucleocapsid virus with negative sense ssRNA. Respiratory transmission. Seen in older children and adults. Causes subglottal swelling with a hoarse, barking cough. In infants this can be the source of colds, bronchiolitis, pneumonia and croup. |
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| RSV |
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| Enveloped, helical nucleocapsid virus with negative sense ssRNA. Respiratory transmission. Can cause colds in adults and can cause bronchiolitis and necrosis of bronchioles in preemies. Also can cause atypical pneumonia. |
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| Human metapneumonia virus (MNV) |
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| Enveloped, helical nucleocapsid virus with negative sense ssRNA. Respiratory transmission. Cause of the common cold in 15% of pediatric cases. Can also cause bronchiolitis and pneumonia. |
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| Rabies virus |
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| Negative sense ssRNA bullet shaped rhabdobiridae. enveloped and helical. A bite from an infected animal can cause the organism to move to the dorsal root ganglia via retrograde transport. Negri bodies can be found in brain tissue post mortem. |
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| Ebola, marburg virus |
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| Negative sense ssRNA Filoviridae virs. Unknown reservoir. Causes fatal hemorrhagic fever. |
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| Influenza virus |
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| Orthomyxovirus with 8 segments. envelope contains 2 glycoproteins, H and N used to serotype the virus. Pathogenesis is due to antigenic drift and shift. Disease can lead to reye syndrome or Guillain barre syndrome. Yearly vaccination. |
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| California and LaCrosse encephalitis virus |
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| Negative sense ssRNA enveloped virus with 3 segments, 1 ambisense. Bunyavirus. Transmitted via the mosquito and can cause viral encephalitis. |
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| Hanta virus |
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| Negative sense ssRNA enveloped virus with 3 segments, 1 ambisense. Bunyavirus. Transmitted via rodent excrement in the four corners region. causes a pulmonary syndrome characterized by cough, myalgia, dyspnea, tachycardia, pulmonary edema, effusion and hypotension. 50% mortality. |
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| Lymphocytic choriomeningitis virus (LCMV) |
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| Arenavirus. Negative sense ssRNA that is pleomorphic. Enveloped. Virons have a sandy appearnace due to the presence of ribisomes in the viron. 2 segments, 1 ambisense. Transmitted via mice and pet hamsters. Causes influenza-like disease with meningeal signs. |
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| Lassa fever virus |
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| Arenavirus. Negative sense ssRNA that is pleomorphic. Enveloped. Virons have a sandy appearnace due to the presence of ribisomes in the viron. 2 segments, 1 ambisense. Spread via rodents or human to hman. Causes hemorrhagic fever with 50% mortality. |
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| Reovirus |
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| Double stranded RNA virus with 10-11 segments. Naked and contains its own polymerase. Icosahedal. spead via fecal oral route and respiatory route. Can cause the common cold and gastroenteritis. |
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| Rotavirus |
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| Double stranded RNA virus with 10-11 segments. Naked and contains its own polymerase. Icosahedal. Spread by fecal oral rout an causes gastroenteritis most commonly in very young children before walking years. Live attenuated vaccine available. |
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| Colorado tick fever virus (CTFV) |
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| Double stranded RNA virus with 10-11 segments. Naked and contains its own polymerase. Icosahedal. Spread by ticks and the virus infects erythroid precursors. Causes a flu-like illness with biphasic fever, conjunctivitis and a possible rash. |
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| Malassezia furfur |
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| Normal skin flora fungus that can cause pityrasis or tinea versicolor. Superficial infection of keratinized cells with a predisposition for disease with warm, moist climates. Can cause fungemia in premature infants. KOH scraping reveals "spaghetti and meatballs". |
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| Trichophyton spp. |
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| Filamentous fungi (monomorphic) dermatophyte that may disseminate in immunocompromised patients. Infects skin, hair and nails. |
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| Microsporum spp. |
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| Filamentous fungi (monomorphic) dermatophyte that may disseminate in immunocompromised patients. Infects Hair and skin. |
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| Epidermophyton spp. |
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| Filamentous fungi (monomorphic) dermatophyte that may disseminate in immunocompromised patients. Infects nails and skin. |
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| Tinea capitis |
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| Ringworm of the scalp. |
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| Tinea favosa |
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| Most serious tinea which can cause permanent hair loss and is very contagious. |
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| Sporothrix schenckii |
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| Dimorphic fungus which is a fungus in the environment and a cigar shaped yeast in tissue. Causes rose gardner's disease. |
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| Histoplasma capsulatum |
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| Fungus that can cause acute pulmonary disease, chronic pulmonary disease or disseminated infection. Hyphae with microconidia and tuberculate macrocnidia in the environment; endemic in the estern great lakes, ohio, mississippi, and missouri river beds. Found in soil enriched with bird or bat feces. Spelunker's disease. Small intacellular yeasts which fill infected RES cells to the brim with small yeasts! Causes fungus flu (a pneumonia). Hepatosplenomegaly may be present. Lesions tend to calcify as they heal. |
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| Coccidioides immitis |
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| Fungus that can cause acute pulmonary disease, chronic pulmonary disease or disseminated infection. Hyphae break up into arthroconidia in desert sand in the environment. Endemic in the southwestern USA. Tissue form is spherules with endospores. Causes desert vally fever with desert bumps (eryhtma nodosum). Pulmonary lesions tend to calcify as they heal. |
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| Blastomyces dermatitidis |
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| Fungus that can cause acute pulmonary disease, chronic pulmonary disease or disseminated infection. Hyphae found in environment are not descriptive. Associated with rotting wood. Endemic in the upper great lakes, ohio, mississippi river beds, and the southeastern seaboard of the US and northern Minnesota into Canada region. Tissue form is broad based budding yeasts and a double refractile cell wall (not capsule). Not as likely to resolve as its counterparts. |
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| Aspergillus fumigatus |
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| opportunistic fungi that is a monomorphic filamentous fungus with septate hyphae branching at 45 degrees. Can cause the formation of a fungus ball, allergic bronchopulmonary aspergillosis, and invasive aspergillosis. |
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| Candida albicans |
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| Yeast endogenous to our mucous membrane flora. Forms germ tubes at 37C in the serum. Pseudohyphae and true hyphae invate tissues (non-pathogenic forms do not). |
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| Cryptococcus neoformans |
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| Encapsulated yeast that is monomorphic. Found in soil enriched with pigeon droppings. Diseases such as hodgkin's lymphoma and AIDS can dispose to infection (leading cause of meningitis in these disease states). NOT the leading meningitis cause in transplant patients. (that would be Listeria monocytogenes). |
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| Mucor, rhizopus, absidia |
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| Nonseptate filamentous fungi found in the soil and inhaled. Non-septate hyphae with broad angles (90 degrees or more). Opportunistic an can cause a rhinocerebral infection commonly occurring in ketoacidotic diabetic patients and leukemic patients. |
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| Pneumocystis Jirovecii |
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| Obligate extracellular fungus that has silver stained cysts in tissues. Can cause interstitial pneumonia in AIDS patients. Causes death of type I pneumocytes and subsequent overproliferation of type II pneumocytes. |
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| Entamoeba histolytica |
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| protozoan parasite that can cause amebiasis (dysentery). Characterized by inverted flask shaped lesions in the large intestine. Blood and puss found in stools. Liver abscesses. Cysts transmitted via fecal oral route. Nuclei have "spokes". |
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| Giardia lamblia |
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| protozoan parasite. Causes a disease where its ventral sucking disk attaches to the lining of the duodenal wall causing a fatty foul smelling diarrhea. Transmitted via cysts in fecal oral transmission. Falling leaf motility. |
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| Cryptosporidium spp., parvium |
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| Causes a condition of transient diarrhea in healthy people, but severe diarrhea in immunocompromised patients. Transmitted via cysts in undercooked meat. Not killed by chlorination. Acid fast oocysts can be found in the stool of infected patients. |
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| Isospora belli |
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| protozoan parasite, causes transient diarrhea in AIDS patients. Mimics giardiasis malabsorption syndrome. Transmitted via oocysts via the fecal oral route. Acid fast and elliptical oocysts in stool. |
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| Cyclospora cayetanensis |
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| protozoan parasite. Causes self limited diarrhea in the immunocompitent and prolonged to severe diarrhea in AIDS patients. Acid fast and spherical oocysts found in the feces of these patients. |
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| Microsporidia |
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| protozoan parasite causing persistent, debilitating diarrhea in AIDS patients. Transmitted via ingested spores. Gram positive acid fast spores in stool or biopsy material. |
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| Trichomonas vaginalis |
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| protozoan parasite causing asymptomatic or frothy vaginal discharge. Yellow-green appearnace, not grayish watery as in a bacterial infection. Corkscrew motility of the trophozoites in methylene blue wet mount. |
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| Naegleria |
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| Free living amoebae that can cause primary amebic meningoencephalitis characterized by a severe prefrontal headache, nausea, fever, and an altered sense of smell. Often fatal. Picked up via diving into warm water. Motile trophozoites in CSF. Tx. is rarely successful. |
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| Acanthamoeba |
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| Free living amoebae that causes keratitis (granulomatous amebic encephalitis) in immunocompromised patients. Progressive to death with insidious onset. Commonly found in contact lens solution. Star shaped cysts seen on biopsy, rarely seen in CSF. |
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| Plasmodium vivax |
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| causative agent of malaria with 48 hour fever spikes. Can see enlarged host cells with ameboid trophozoites. Liver stage show persisten hypnozoites and can relapse. Treat with chlooquine then primaquine. |
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| Plasmodium ovale |
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| causative agent of malaria that causes 48 hour fever spikes. Can see oval, jagged, infected RBCs on blood smear. Persistent hypnozoites seen in the liver; can relapse. Treat with chloroquine then primaquine. |
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| Plasmodium malariae |
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| causative agent of malaria that is characterized by 72 hour fever spikes and the potential for recrudescence (the reoccurrance of symptoms from low levels of organisms remaining in red cells). Bar and band forms and rosette schizonts seen on blood smear. No persistent liver stage. Treat with chloroquine. |
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| Plasmodium falciparum |
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| causative agent of malaria. Causes irregular fever spies and severe fever. Can see multiple ring forms and cresent shaped gametes on blood smear and has no persistent stage (but can have recrudescence). Treat with chloroquine, but chloroquine resistance is becoming a problem. |
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| Trypanosoma cruzi |
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| Hemoflagellate. Causative agent of Chagas disease. Spread by the Reduviid bug (kissing or cone bug) which passes the organism through its feces and scratching implants it into the human host. Trypomastigotes are diagnostic. |
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| Trypanosoma brucei, gambiense, rhodsiense |
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| Hemoflagellate. Causes african sleeping sickness. Spread by the tsetse fly. |
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| Leishmania donovani |
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| Hemoflagellate. Causes visceral leishmaniasis spread by the sandfly. In rural areas, the reservoir is rodents and wild animals, while in urban areas the reservoir is humans. |
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| Leishmania braziliensis |
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| Hemoflagellate. Causes mucocutaneous leishmaniasis. Spread by the sandfly bite. In rural areas, the reservoir is rodents and wild animals, while in urban areas the reservoir is humans. |
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| Babesia microti |
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| Causes a disease that is malaria like and has the same range as lyme's disease in terms of epidemiology. Spread by the Ixodes tick and can be a co-infection with borrelia. Maltese cross tetrad seen in RBCs. |
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| Toxoplasma gondii |
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| Cause of disease due to cat feces in pregnant women. Can cross the placenta. |
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| S. mansoni, S. japonicum |
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| Trematode (fluke) with reservoirs in cats, dogs, cattle, and other animals. Can penetrate skin. Can cause itching at the penetration site and matures in mesenteric veins. Eggs can cause granulomas in the liver. Subterminal spine seen on the ova. |
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| S. haematobium |
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| Trematode (fluke) that has a primate host. Can penetrate the skin and matures in bladder veins. Terminal spine found in Ova. "male menstruation". |
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| Non-human shistosomes |
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| Cause "swimmer's itch" and cause intense itching. Can't really spread due to lack of a proper host. |
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| Paragonimus westermani |
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| Trematode (fluke) of the lung. Mimics pulmonary TB and specifically targets the lungs. Can see operculated eggs. |
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| Taenia saginata |
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| cysticerci ingested from beef; intestinal tape worm. Dx by seeing proglottids in feces. |
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| Taenia solium |
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| pork tapeworm. Can cause cysticercosis (eggs or larva develop in the brain, heart, eye, etc. causing adult onset epilepsy). Can dx. by biopsy or by proglottids in feces. |
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| Diphyllobothrium latum |
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| Fish tapeworm. Can be obtained by drinking pond water. Sparganosis (larvae penetrate intestinal wall and encyst. Proglottids in feces. |
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| Echinococcus granulosus |
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| Cause hydatid cyst disease in the liver and lung where cysts containing brood capsules develop. Spread by egg ingestion. |
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| Echinococcus multiocularis. |
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| Causes alveolar hydatid cyst disease in which the cysts are metastatic. Needs surgical resection. |
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| Enterobius vermicularis |
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| Most frequent helminth parasite in USA. Pinworms, causes perianal itching. Autoinfection and person to person spread. Sticky swab of the perianal area for dx. Flattened ova with larvae inside can be seen. |
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| Trichuris trichiura |
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| Whipworm cecum. Spread by egg ingestion. Can cause a prolapsed rectum. Barrel saped eggs with bipolar plugs can be seen in the stool. |
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| Ascaris lumricoides |
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| Most common helminth worldwide; also the largest. Eggs are ingested, then larva migrate through the lungs and mature in the SI. May cause obstruction. Bile staned knobby eggs can be found. |
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| Toxocara canis or cati |
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| Causes visceral larva migrans because this organism is not normally an agent that infects humans. Dx. based on clinical findings. |
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| Necator americanus |
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| New world hookworm with lung migration. Filariform larva penetrates the intact skin of bare feet. Fecal larvae can be found. |
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| Ancylostoma braziliense, A. caninum |
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| Causes cutaneous larva migrans with intense skin itching. Penetrates skin, but can't mature in humans. |
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| Strongyloides stercoralis |
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| Threadworm; with early infection causes pneumonitis, abdominal pain and diarrhea; but later causes malabsorption, ulcers and bloody stools. Larvae can be found in stool. |
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| Trichinella sprialis |
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| Larvae encyst in muscle causing pain. Viable encysted larve are first found in meat that is consumed (commonly wild game meat). |
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| Wucheria bancrofti |
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| Causative agent of elephantiasis due to blocked lymphatic flow. Transmitted via mosquito. Dx made by eosinophilia and microfilariae in blood. |
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| Loa loa (african Eye worm) |
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| Causes pruitis and calabar swellings of the eyes. Spread by mango flies. Needs surgical removal of this worm or worms from the eye. |
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| Onchocerca volvulus |
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| Cause of river blindness with an itchy "leopard" rash. Transmitted via backflies. Dx. by skin samples for calabar swellings. Need to surgically remove the worms. |
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| Dracunculus medinensis |
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| Causes creeping eruptions and ulcerations of the skin. Transmitted via drinking water with infected copepods. Dx. via increased IgE, and the worm erupting from the skin. Needs slow removal with a stick (thought to be the source of the worm around the stick seen in the symbol of medicine). |
