zChapter 12 Clinical Bacteriology – Flashcards
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| S. aureus |
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| skin, subcutaneous infections, bacteremia,endocarditis, toxic shock, food poisoning catalase +, facultative anaerobes |
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| S. epidermidis |
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| opportunistic, nosocomial infections normal skin flora and an opportunist that causes endocarditis of artificial heart valves catalase +, facultative anaerobes |
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| Streptococcus pyogenes |
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| ?-hemolytic |
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| Streptococcus agalactiae |
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| Group B Beta hemolytic Normal flora of GI urogenital tracts Infection acquired in utero at birth Neonatal bacteremia, pneumonia, meningitis |
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| Streptococcus pneumoniae |
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| Alpha hemolytic Lancet shaped in pairs Inhabitant of oropharynx Antiphagocytic capsule Diseases Otitis media Sinusitis Pneumonia Meningitis |
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| Enterococcus species |
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| ?-hemolyti |
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| Viridans streptococci |
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| Normal oral flora Several species Disease Endocarditis During dental work, they can gain entrance to the blood and have a predilection for heart valves causing endocarditis. This is why a dentist often prescribes antibiotics for those undergoing extensive dental work |
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| Enterococcus faecalis |
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| Normal large bowel flora Opportunists Urinary and biliary tract infections |
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| Neisseria gonorrhoeae |
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| “gonococcus’ Gonorrhoeae Sexually transmitted disease Neonatal conjunctivitis Associated with chlamydial infection Pili promote adherence |
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| Neisseria meningitidis |
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| Colonizes nasopharynx Meningitis Aerosol droplet transmission Antiphagocytic capsules Carriers Waterhouse-Friderichsen syndrome |
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| Bacillus anthracis- |
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| Gram positive bacilli Spore formers Ubiquitous- soil, water Exotoxin producers anthrax |
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| Bacillus cereus |
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| Gram positive bacilli Spore formers Ubiquitous- soil, water Exotoxin producers poisoning |
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| Listeria monocytogenes |
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| Gram positive coccobacillus Normal animal GI flora Transmission via contaminated food and dairy products Intracellular growth with cell to cell transfer Septicemia and meningitis Granulomatosis infantiseptica |
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| Corynebacteria diphtheriae |
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| Gram positive, small club shaped bacillus Oral cavity /throat infection Exotoxin inhibits protein synthesis Phage carries toxin gene Diphtheroids normal throat inhabitants Diphtheria Aerosol droplet transmission Vaccine Antitoxin |
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| Clostridium tetani |
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| causes tetanus or lockjaw. It is the “step on a rusty nail” bacteria that vegetates in the host and produces a tetanospasm exotoxin that interferes with the nervous system leading to skeletal muscle contraction and eventual death by respiratory failure. Immunization with the toxoid is extremely effective, DPT. Antitoxin can be effective if administered before the toxin attaches to its receptors, but is usually too late. Gram positive bacilli Anaerobic Spore forming Exotoxin producing Ubiquitous Four medically important species |
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| Clostridium botulinum |
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| the cause of food poisoning with one of the deadliest toxins known. The exotoxin blocks release of acetycholine leading to flaccid paralysis. Spores in foodstuffs germinate under anaerobic conditions producing the toxin. Preformed toxin is often the cause of disease in home canned foods. Contaminated honey eaten by infants allows the organisms to grow in the GI tract but is a milder disease Gram positive bacilli Anaerobic Spore forming Exotoxin producing Ubiquitous Four medically important species |
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| Clostridium perfringens |
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| responsible for gas gangrene often seen in wounds. It is not only found in soil , but is a normal flora of the intestinal tract and can invade wounds contaminated with soil or human waste. It produces many virulence factors of which alpha toxin is very important in causing lysis of host cells. Gas production by the organism results in the bubbly formations of infected tissue. Antitoxin and antibiotics along with debridement of infected tissue are treatment. Gram positive bacilli Anaerobic Spore forming Exotoxin producing Ubiquitous Four medically important species |
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| Clostridium difficile |
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| part of the normal intestinal flora that acts as an opportunist when antibiotics kill off other normal flora allowing it to proliferate. It is frequently a nosocomial infection but is becoming more common in the general population. It produces an enterotoxin that causes diarrhea and destroys intestinal lining thereby producing a pseudomembranous colitis. Laboratory diagnosis requires the toxin to be identified since the organisms are normal flora. Gram positive bacilli Anaerobic Spore forming Exotoxin producing Ubiquitous Four medically important species |
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| Escherichia coli |
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| Gram negative bacilli Normal flora of large intestine Ubiquitous, soil, vegetation, water LPS important endotoxin Transmission- self inoculation, person to person, food, water Become pathogenic via transfer of DNA Antigenic classification Diseases Many strains categorized by pathology Strains have acronym names Pathology followed by E coli is sequence for names EHEC ETEC EPEC, EIEC, EAEC |
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| S dysenteriae |
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| produces the most severe disease of the 4 species through Shiga toxin which inhibits protein synthesis, and is often epidemic in developing countries. Shigellosis or bacillary dysentery is the disease and entails profuse watery diarrhea, cramping, mucous and blood in stools and tenesmus. Shigella inject toxins directly into adjacent host cells using the type III secretion system |
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| S sonnei |
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| the species found most in the U S and is a milder form of the disease. Only a few hundred Shigella need to be swallowed to cause disease compared to other bacteria where thousands are necessary. This means Shigella can survive the acidic pH of the stomach. Dysentery: inflamed intestine, especially, colon with abdominal pain, tenesmus, frequent stools containing blood & mucous. |
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| Salmonella typhimurium |
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| the most common species. They cause nausea, vomiting, cramping and non-bloody diarrhea Gram negative bacilli Normal animal intestinal flora Not normal human flora Many serotypes based on surface antigens Transmission via food and water GI disease Carriers |
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| Salmonella enteritidis |
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| the most common species. They cause nausea, vomiting, cramping and non-bloody diarrhea Gram negative bacilli Normal animal intestinal flora Not normal human flora Many serotypes based on surface antigens Transmission via food and water GI disease Carriers |
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| Salmonella typhi |
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| invades colonic cells and is transported in macrophages to other parts of the body since it resists killing by the phagocytes. When this occurs, there is fever and inflammation of the infected organs and then the bacteria are returned to the intestine and cause GI disease. This scenario is termed typhoid fever. After recovery, in a small percentage of cases, the bacteria can remain in the gall bladder and be shed in the stool. This is the carrier state. Gram negative bacilli Normal animal intestinal flora Not normal human flora Many serotypes based on surface antigens Transmission via food and water GI disease Carriers |
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| Yersinia enterocolitica |
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| Carried in livestock and wild animals Transmission-food, water, blood Bloody diarrhea long lasting |
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| Yersinia pestis |
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| Bubonic plague bacillus Transmission-fleas and aerosol droplets 75% mortality rate |
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| Haemophilus influenzae |
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| without capsules are normal flora of the upper respiratory tract. The capsule, when present, is a critical virulence factor along with LPS. Organisms are transmitted via aerosol, invade the upper respiratory tract mucous membranes, enter the blood and then the CNS. There are 6 antigenic capsular types, a through f. Type b (Hib) is the most virulent and was a major cause of meningitis in infants until the current vaccine began to be used. An initial vaccine was made to react with the polysaccharide capsule of the organism, but didn’t work very well. Can you remember why this would be so? The current vaccine is conjugated to diphtheria toxoid (protein) and provides good immunity. Hib meningitis is still a significant disease in developing countrie Infant meningitis Erroneous blame for great pandemic of 1918 |
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| Haemophilus ducreyi |
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| causes chancroid, a sexually transmitted disease that resembles syphilis in males but is often asymptomatic in females. |
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| Legionella pneumophila |
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| Gram negative coccobacilli, stains poorly Facultative intracellular American Legion outbreak, 1976 Atypical pneumonia Pontiac fever Inhibit phagolysosome fusion in phagocytes Transmission aerosol from water sources |
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| Bordetella pertussis |
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| Small Gram negative, encapsulated ,coccobacilli Whooping cough Transmission- aerosol, person to person Filamentous hemagglutinin Exotoxins destroy ciliated epithelium of trachea Vaccine (DPT) protection |
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| Pasteurella multocida |
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| Bites, scratches from dogs, cats Cellulitis Brucella animal disease, 4 species Transmission to humans via skin GI or respiratory tracts Undulant fever |
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| Francisella tularensis |
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| Capsule, intracellular growth Very high infectivity Tick bites and direct contact with ex rabbit, inhalation, ingestion |
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| Bartonella henselae |
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| causes cat scratch fever which consists of fever, abdominal pain and lesions around the scratch or bite. |
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| Vibrio cholera |
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| causes cholera which is a severe watery, non bloody diarrhea. The diarrhea is characterized by “rice water stools” indicating all fecal material is gone and mucous flecks give the liquid a milky appearance. In infants, dehydration is the immediate problem with electrolyte and fluid replacement necessary for survival. The fecal oral route is responsible for spread. Large inocula are necessary to establish infection, therefore direct person to person spread is unlikely, while drinking contaminated water or eating contaminated, uncooked shellfish are responsible for most disease. Pili and other adhesins permit the organism to attach to the mucosal epithelium and establish residency. Cholera toxin, seen in the next slide, is responsible for the severe diarrhea. Untreated cholera has a high mortality rate. Carriers who have recovered from the disease are a reservoir and shed organisms Gram negative comma shaped Halophilic (salt loving) |
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| Vibrio parahemolyticus |
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| found in estuary water is acquired primarily through ingestion of raw shellfish and produces an explosive watery diarrhea Gram negative comma shaped Halophilic (salt loving) |
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| Vibrio vulnificus |
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| also found in salt water, can be ingested and cause diarrhea, but also can cause serious disease via wound infection in contaminated water resulting in septicemia, necrosis of tissue and death. Gram negative comma shaped Halophilic (salt loving) |
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| Campylobacter jejuni |
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| Most common cause of bacterial gastroenteritis in US (2-3 million cases/year) not reportable Reservoirs: GI tract of farm animals Spread: Inadequately prepared food and drink (1000-10,000 organisms necessary for infection) Organisms multiply in the small intestine, invade the epithelium and produce inflammation Rapid onset of watery to bloody diarrhea, abdominal cramping, slight fever |
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| Heliobacter pylori |
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| Reservoir – human gastric lumen Grows in mucous layer near epithelial surface where pH is 7.4 Produces adhesins, acid inhibitors and urease, which breaks down urea yielding ammonia which buffers stomach acid Responsible for gastritis, peptic ulcer, gastric adenocarcinoma Often present without signs or symptoms and presence increases with aging |
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| Pseudomonas aerugenosa |
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| Gram negative , encapsulated rod Ubiquitous, opportunist Does not ferment glucose “nonfermenter” Opportunist, not normal flora but can persist in debilitated patients Pyocyanin - blue pigment, fruity odor Many diseases, nosocomial Highly antibiotic resistant |
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| Bacteroides fragilis |
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| Anaerobic, encapsulated Gram negative bacilli Comprise 50% of fecal matter, normal flora Little or no endotoxin toxicity Opportunist Infection after bowel perforation Most clinically significant of Gram negative rod normal flora |
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| Treponema pallidum |
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| Causes syphilis (sexually transmitted disease {STD}), venereal disease Corkscrew (helical) shape Motile via flagella Gram negative Too thin (0.1 micron) to be seen under brightfield microscope Not cultivated on laboratory media |
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| Borrelia burgdorferi |
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| Gram negative, long, thick spiral Lyme disease Many manifestations Zoonotic Transmission: Ixodes tick saliva Reservoir: Deer, mouse Bulls eye (erythema chronicum migrans) Serological diagnosis |
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| C pneumonia |
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| causes a bronchitis and pneumonia transmitted by person to person aerosol droplets. Obligate intracellular bacteria “Energy parasites” unable to make ATP Life cycle with two forms Small pleomorphic, Gram-negative No peptidoglycan Elementary body-infectious agent Reticulate body-replicative form Zoonotic |
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| C psittaci |
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| causes parrot fever or psittacosis. This disease is transmitted by inhalation of contaminated, dried, bird feces and causes illnesses ranging from a mild flu-like illness to serious pneumonia with CNS involvement. Obligate intracellular bacteria “Energy parasites” unable to make ATP Life cycle with two forms Small pleomorphic, Gram-negative No peptidoglycan Elementary body-infectious agent Reticulate body-replicative form Zoonotic |
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| Rickettsia |
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| RMSF,caused by Rickettsia, is seen most often in the eastern US as opposed to the rockies. Tick bite, fever and rash are the triad for RMSF clinical diagnosis. The disease is characterized by high fever, rash, headache and myalgias. Complications can lead to encephalitis, renal failure respiratory failure, DIC and death Small, Gram negative bacilli Obligate intracellular Zoonotic-ticks, lice, fleas Intracellular growth protects Many species of each Genera and more Genera |
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| Ehrlichia |
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| cause a disease similar to RMSF, but without rash Small, Gram negative bacilli Obligate intracellular Zoonotic-ticks, lice, fleas Intracellular growth protects Many species of each Genera and more Genera |
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| Coxiella |
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| cause Q fever which is an acute febrile illness with complications of pneumonia and endocarditis Small, Gram negative bacilli Obligate intracellular Zoonotic-ticks, lice, fleas Intracellular growth protects Many species of each Genera and more Genera |
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| Mycobacteria tuberculosis |
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| Aerobic, acid fast bacilli Facultative intracellular Cell wall lipids-survival in macrophages Slow grower 50% mortality in untreated Transmission- aerosol droplets Chronic disease Symptomatic disease - fever, coughing, bloody sputum- weight loss, loss of energy- progressive lung damage- bacteria may escape lungs ==> systemic disease Organisms continue to multiply- macrophages die, organisms rephagocytosed - macrophages fuse, yielding multinucleated giant cells- layers of macrophages, T-cells forms around damaged tissue, this walls off lesion with thick fibrin coat    * granuloma, specifically called tubercle    * calcification ==> lesions in chest X-rays |
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| Mycoplasma pneumoniae |
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| Smallest free living bacteria Wall-less- pleomorphic Resistant to cell wall inhibitors Ubiquitous Primary atypical pneumonia Aerosol transmission Mild, low grade fever Nonproductive cough |
