Microbiology Final Exam Test Questions – Flashcards

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What is pneumococcal meningitis caused by?
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Streptococcus pneumoniae
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Where is Streptococcus found normally?
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In the throat. Part of the normal microbiota.
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This is a Gram+ lancet-shaped coccus. Often seen in pairs.
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Streptococcus Pneumoniae
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Many strains of this bacteria are protected from phagocytosis by a polysaccharide capsule.
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Streptococcus Pneumoniae
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What does Streptococcus pneumoniae commonly cause?
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Otitis media, sinusitus, and pneumonia...any of which can precede pneumoncoccal meningitis.
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What is damage in Meningitis largely due to?
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The sever inflammatory response. Causes brain swelling and clots form in capillaries and block blood supply.
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What is the most deathly form of meningitis?
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Streptococcus pneumoniae
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What is used to treat pneumoncoccal meningitis usually?
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Penicillin
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This bacteria is frequently responsible for epidemics of meningitis.
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Neisseria meningitidis
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Where is Neisseria meningitidis usually found?
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commonly part of the normal respiratory microbiota.
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Symptoms of this are similar to that of pneumococcal meningits, but also may include petechia. (purplish spots on the skin.)
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Neisseria meningitidis
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this can lead to septic (endotoxic) shock
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Neisseria meningitidis
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A gram - encapsulated diploccus. Like Niesseria gonorrhoeae, it can vary in its anitgens and acquire DNA through gene transfer easliy.
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Neisseria meningitidis
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These bacteria attach by pili to mucous membranes and multiply. Proteins in their outer membranes all the bacterial cells to pass through the epithelial lining in the resp tract and into the blood to the meninges. (rare)
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Neisseria meningitidis
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This bacteria releases blebs of the outer membrane and the endotoxin causes vasodilation and capillary leakage leading to drop in blood pressure and septic shock.
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Neisseria meningitidis
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Avoid phagocytosis with capsule
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Neisseria meningitidis
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Person to person transmission via respiratory droplets. Easy transmission in crowded, stressed populations
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Neisseria meningitidis
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Meningitis is the most common result of the food-borne disease of this bacteria
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Listeria monocytogenes
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Infections by this are usually mild in most healthy people. Fever and muscle aches and sometimes nausea or diarrhea.
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Listeria monocytogenes
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Pregnant women who become infected usually miscarry or deliver terminally ill babies.
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Listeria monocytogenes
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A motile, non-spore forming, facultative anaerobis, gram + rod that can grow at 4 degrees celcius. (Can grow on vaccum packed refrigerated foods)
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Listeria monocytogenes
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Mode of entry of Listeria monocytogenes is usually what?
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The GI tract
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These bacteria penetrate the intestinal mucosa through the M cells and into the Peyers patches and into the blood.
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Listeria monocytogenes
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Can be killed with penicillin, but you must catch it quickly, especially in pregnant women.
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Listeria monocytogenes
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This food borne disease can be killed by thouroughly cooking meat. Soft cheeses may carry as well as raw veggies.
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Listeria monocytogenes
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Disfigurement, loss of limbs, and blindness can result from this bacteria.
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Mycobacterium leprae
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Aerobic, rod-shaped, acid fast bacteria. Grows very slowly with a generation time of about 12 days.
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Mycobacterium leprae
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Preferentially infects peripheral nerves. From there the course depends on the persons immune system.
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Mycobacterium leprae
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When the cell-mediated immunity succeffully stops the proliferating bacteria Mycobacterium leprae, the disease is called what?
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tuberculoid leprosy
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When cell-mediated immunity fails to develop or is suppressed.
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lepromatous leprosy
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This bacteria causes a severe form of intoxication that can eventually lead to paralysis.
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Clostridium botulinum
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What does the exotoxin produced by C.botulinum do? What type of toxin is it?
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It is an A-B toxin.
The A portion enters the nerve cell and inactivates proteins that regulate the release of neurotransmitter.
The B portion binds to specific receptors on the motor nerve endings.
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This is a strictly anaerobic Gram +, spore-forming, rod-shaped bacterium that can cause paralysis if you ingest it. (via its' exotoxin)
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Clostridium botulinum.
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There are several types of neurotoxin that Clostridium botulinum produces. What are three that are key to human cases?
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The A, B, and E type strains
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How does Clostridium botulinum produce paralysis?
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the toxin attaches to the motor neurons blocking transmission of signals to the muscles.
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Where does intestinal botulism usually occur?
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in infants. (Honey!)
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In what way does Clostridium botulinum usually cause death?
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it causes respiratory paralysis.
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Epidemic viral encephalitis is usually caused by what?
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Arboviruses (arthropod borne viruses)
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THis is a group of enveloped, single stranded RNA viruses transmitted by insects, mites or ticks
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Arboviruses
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What are some examples of arboviruses?
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Lacrosse encephalitis
West Nile encephalitis
eastern and western equinine viruses.
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What type of bacteria is Staphylococcus aureus?
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It is a gram+ cocci in clusters. Coagulase positive. Facultative anaerobes. pyogenic (pus producing)
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Where does Staphylococcus aureus normally reside?
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It is part of the normal microbiota. Up to 20% of healthy people carry it in their nose.
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What can Staphylococcus aureus cause in the body?
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It plays a role in hair follicle infections(boils and carbuncles), Food-borne intoxication, Toxic shock syndrome, and is the leading cause of wound infections.
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What is the medical significance of Escherichia coli? (E. coli)
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Normal microbiota of intestinal tract. Some strains cause
1. urinary tract infections
2. types of intestinal disease
3. some cause meningitis in newborns
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What type of bacteria is E. coli?
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A gram - rod
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What is an exotoxin?
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A protein that a pathogen produces that has very specific damaging effects
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What does STEC stand for? What is the most common one? What does it cause?
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1. Shiga-toxin producing E.coli
2. The most common strain is 0517:H7
3. It causes colonization in the large intestine and leads to Fever, cramps, bloody diarrhea, and some hemolytic uremic syndrome.
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What are ETEC? What do they cause?
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Enterotoxigenic E.coli. THey make pili that allow them to colonize the small intestine. secrete enerotoxins.
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WHat are EIEC? What do they cause?
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Enteroinvasive e coli.
They invade the intestinal epithelium and cause disease similar to shigellosis.
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What are EPEC? What do they cause?
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Enteropathogenic E.coli.
They produce pili that allow them to colonize the small intestine where they inject effector proteins that cause A/E lesions.
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What are EAEC? What do they cause?
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Enteroaggregative E.coli. THey have pili and adhere to intestinal epith. They grow in characteristic aggregations in a thick mucous associatec biofilm. They produce enterotoxins and cytotoxins that damage cells and cause an inflammatory response.
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DAEC? What do they cause?
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Diffusely adhering Ecoli. like EAEC, but they grow as a diffuse layer.
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What does Streptococcus pyogenes cause?
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Strep throat, scarlet fever, wound infections(Flesh-eating disease).
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What type of bacteria is Streptococcus pyogenes?
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a gram + coccus that grows in chains. Characterized by the A carb in the cell wall.
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What are some of the mechanisms S.pyogenes uses to evade host response?
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a special adhesin to attach, M protein which also interferes with phagocytosis,
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What do Psuedomonas aeruginosa infections cause?
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Opportunistic pathogen. Widespread in environment. health-care assoc infections, and outside hospital. Produces two pigments that color wounds green.
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What type of bacteria is Pseudomonas aeruginosa?
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an aerobic, gram- rod with a single polar flagellum.
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This type of bacteria is a non-invasive, anaerobic gram+ rod that produces am extoxin that prevents inhibitory neurons from releasing their neurotransmitter. (musles contract without control)
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Clostridium tetani
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This is the exotoxin produced by C. tetani
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tetanospasm
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This bacteria causes pain and swelling in wound infections, followed by discharge of a thin brown bubbly fluid and dark discoloration of overlying skin. THe toxin causes tissue necrosis.
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Clostridium perfringens
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This is an alpha toxin producing anaerobe
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C. perfringens
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What does C. perfringens produce?
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Clostridial Myonecrosis (Gas Gangrene)
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How do you avoid/ fix gangrene?
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Clean wounds and remove dead tissue asap so that it doesn't have space to produce toxins
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What are the most common ways wound infections occur?
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they happen easily in hospitals where the skin is broken. THey usually happen from normal microbiota of the environment.
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What are the two bacteria that cause the most wound infections?
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S.aureus and S. epidermidis
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what property of S. epidermidis help it to colonize plastic materials used in medical procedures?
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It binds to fibronectin the blood protein that quickly coats surgical implants in the body.
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This is a Beta- hemolytic gram + chain forming, aerotolerant bacteria
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S. pyogenes
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This protein also binds fibronectin like S.epidermidis. (An F protein)
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S. pyogenes
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Strains of this produce exotoxin A, A superantigen that causes toxic shock and exotoxin B which is a protease that destroys tissue
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Strains of S. pyogenes
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What is the bacteria that causes severe infection in burns that has a greenish tint?
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P. aeruginosa
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This is a gram- facultatively anearobic coccobacillus. Most isolates have capsules. It usually causes infections due to animal bites.
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Pasteurella multocida
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If untreated, bite wounds infected by this bacteria can cause bacteremia leading to endocarditis or meningitis.
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Pasteurella multocida
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Cat scratch disease is caused by this curved, gram- rod.
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Bartonella henslae
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THis is a short, curved, gram-, macroaerophilic bacterium that can cause peptic ulcers. It has multiple polar flagella covred by sheaths.
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Helibacter pylori
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Infection by this bacterium can persist for year or even life. they produce urease(an enzyme that converts urea to ammonia) and burrow within mucous
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Helibacter pylori
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What bacteria causes dental caries?
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Streptococcus mutants
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these are gram+ cocci that live only on teeth.
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streptococcus mutants
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an association of these three bacteria contribute to periodontal disease.
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1.porphyromonas gingivalis,2. Treponema denticola and 3.Tannerella forysthia
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This is a ds enveloped virus that contains linear DNA. There are two types of the virus. One causes oral infections (cold sores) and the other causes genital infections(herpes)
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HSV-1 and HSV-2 Herpes Simplex Virus
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WHy does HSV-1 cause reccurent cold sores?
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Because its non infectious DNA persists in sensory nerves and the DNA becomes the source of infectious virions that are carried to the skin or mucous membranes causing sores.
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this type of toxin involved in intestinal infections causes water and electrolytes to flow from intestinal cells.
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enterotoxins
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This type of toxin in intestinal infections causes cell death. some types can be absorbed into the blood stream resulting in systemic effects.
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cytotoxins
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Characteristic damage caused when bacteria inject proteins that rearrange actin filaments resulting in the replacement of microvilli on the intestinal surface with a thick structure or "pedestal" under the bacterium.
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Attaching and effacing (A/E lesions)
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What is the third way bacterium attack intestinal cells?
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through cell invasion. They go into and take over the cell.
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This bacterium causes potentially fatal diarrhea. (watery diarrhea) Person can lose up to 20 liters a day! Rice water stool. Loss of fluids and electrolytes can cause death without oral rehydration therapy.
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Cholera caused by Vibrio Cholerae
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This bacterium in killed by stomach acid, but if enough are ingested it can get in a produce an enterotoxin that activates ion transport channels causing chloride and other electrolytes to exit the cells.
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Vibrio cholerae
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THis toxin in an A-B toxin. The b portion attaches irreversibly to receptors on the microvilli of epithelial cells ,the a (active) portion enters the cell and activates G prtoeins that usually regulate the in and outs of the cell.
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Vibrio cholerae
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How are most intestinal infections spread?
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Via the fecal-oral route
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These are gram- rods that classically cause dysentery.
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Shigella (S. dysenteriae)
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THis species invades intestinal epithelial cells causing a strong inflammatory response.
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Shigella
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Some strains of this produce a potent cytotoxin known as a shiga toxin(A-B toxin) It is responsible for HUS (hemolytic uremis syndrome)
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Shigella dysenteraie
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This causes red blood cells to break up in tiny blood vessels resulting in anemia and kidney failure
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HUS (hemolytic uermic syndrome)
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What two things can cause HUS?
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Shigella dysenterae and some E coli strains
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This bacterium is not motile by itself but over takes the actin of the cells it invades and causes the cells to run into other cells and spread infection
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shigella syseteriae
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This is a gram- rod that induces uptake by epithelial cells in the region btwn th esmall and large intestine. Bacteria multiply in the phagosome and then discharge at the base of the cell. inflammatory response increases fluid secretion.
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Salmonella enterica (S. enterica)
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Ingestion of food contaminated by animal feces, especially poultry
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samlmonella enterica
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What are typhoid and paratyphoid fever caused by?
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Typhoid fever is caused by Salmonella serotype Typhi. Paratyphoid fever by Salmonella serotype paratyphi
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These are gram- members of the Enterobacteriaeceae family. They are serotypes of Salmonella
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typhi and paratyphi
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This bacterium is a curved gram- microaerophilic rod
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Campylobacter jejuni (C. jejuni)
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This bacterium has a low infected dose the bacteria multiplies within and beneath the epithelial cells causing inflammatory response.
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C. jejuni (Campylobacter jejuni)
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This is a gram+, rod that is endospore forming and an obligate anaerobe. The endospores are highly resistant to common disinfectants.
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C. difficile (Clostridium difficile)
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This bacteria has toxins that disrupt host cell actin, causing lethal effects to the intestinal epithelium.
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C. difficile
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This disease primarily occurs in hospitalized patients on antibiotic therapy
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C. difficile (CDAC-Clostridium difficile associated disease.)
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These type of virus account for nearly 500,000 deaths of children worldwide due to lack of fluid replacemtn
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rotavirus
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These are naked viruses with double walled capsid and double stranded segmented RNA
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rotavirus
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THese are naked, SS RNA viruses that are the most common cause of viral gastroenteris in the US.
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norovirus
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This virus causes abdominal cramping vomiting and diarrhea lasting 12 to 60 hrs
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Norovirus
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This is a naked, ss RNA virus of the picornavirus family. It usually has mild symptoms, but often prolonged full recovery. Vaccine is available
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Hep A
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This is an enveloped DS DNA hepadnavirus that is transmitted through blood and semen. It often has acute symptoms and if chronic can lead to cirrhosis and cancer
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Hep B
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This is an enveloped, SS RNA flavavirus . It has no vaccine. It usually has few symptoms, but liver damage can lead to cirrohsis and cancer
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Hec C
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WHen an infection becomes ______, it means that it has been carried to all parts of the body, producing disease in one or more vital organs.
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Systemic
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Illness that results from a circulating agent or its toxins
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sepsis (blood poisoning)
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When a substance is circulating in the blood stream, the condition is given that specifies the nature of the substance. Ex?
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bacteremia, viremia, fungemia (Does not necessarily mean disease)
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WHen sepsis causes blood pressure to fall to such low levels that blood flow to vital organs is insufficient.
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septic shock
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This term is used to describe infections of the heart valves or the inner surfaces of the heart.
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endocarditis
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This starts suddenly with a fever and is usually caused by virulent species such as S. aureus and S. pneumoniae. Can infect normal and abnormal heart valves.
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Acute bacterial endocarditis
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This is an infection of the heart valves and inner surfaces of the heart that is slower and not usually caused by virulent species. (less likely to be fatal)
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subacute bacterial endocarditis (SBE)
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Where do bacteria in SBE come from usually?
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from dental procedures, tooth brushing, trauma.
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What usually causes SBE?
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Staphylococcus epidermidis and other normal microbiota of the skin or mouth
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Why do the microbes live in the heart valves?
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They get caught in thin blood clots formed around deformes heart valves or other areas with disturbed bloodflow. They multiply and create a biofilm.
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How does a biofilm evade host immune response?
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They are protected from phagocytosis and antimicrobial medications.
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How does SBE lead to sickness?
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The bacteria continually wash off into the bloodstream and pieces of the infected clot can break off and block important blood vessels which can lead to death of tissue.
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This is a component of the outer membrane of the gram- cells that can cause symptoms such as fever and shock. Lipid A is responsible for the effects of this
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endotoxin
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The most fatal cases of sepsis usually involve gram ____ bacteria like E.coli P. aeruginosa and other Enterobacteriacea species .
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gram negative bacteria
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What is sepsis initially caused by?
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It usually begins with an infection somewhere in the body other than the bloodstream. It is initially due to and overstimulation of the inflammatory response.
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Widespread clotting often associated with Sepsis and often accompanied by hemorrhage.
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Disseminated intravascular coagulation. (DIC)
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What are the steps of sepsis?
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1. TLRs on macrophages and neutrophils detect endotoxin or other PAMPs, and phagocytess release pro-inflammatory cytokines. WHen this occurs systemically, a cytokine storm results and further activation of the complemnet system.
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Bacteriocidcal antibiotics often lyse bacterial cells and release more endotoxin, resulting in worsening of this blood infection.
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Sepsis
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What are some of the effects of sepsis?
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fever, impaired oxygen exchange, increased leakage of plasma from blood vessels, tissue damage from clotting, etc...
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This disease is widespread in the US and found in rabbits, muskrats, and bobcats.
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Tularemia
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This organism causes Tularemia
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Francisella tularensis
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This is a non-motile, aerobic, Gram- rod that enters through breaks in the skin or mucous membranes and is carried to the regional lymoh nodes making them large and tender.
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Francisella tularensis
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THis organism is ingested by phagocytic cells and grow within them, then spread throughout the body
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Francisella tularensis
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This organism is considered a category A risk for bioterrorism.
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Francisella tularensis
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This
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This is a part of the family Enterobacteriaceae, is a gram- rod, and is facultatively anaerobic. It is non motile and is spread widely through fleas.
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Yersinia pestis (Plague)
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If transmitted through fleas, Y. pestis results in ______ ______.
If spread through inhalation, Y.pestis results in _______ ________.
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1.bubonic plague
2. pneumonic plague
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If Y.pestis spread via the bloodstream, the person may develop ____ ______. Which could lead to DIC (disseminated intravascular coagulation)
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septicemic plague
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This organism forms biofilms in the diegestive tract of infected fleas so that when they try to feed, they actually regurgitate the bacteria into the bite wound
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Yersinia pestis (plague)
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This is a ds DNA virus of the herpesvirus family.
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EBV Epstein-Barr virus
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What disease does EBV cause?
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Mono
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This virus infects the mouth and throat and then becomes latent in another cell type.
After that, it is carried to the lymph nodes where is infects B lymphocytes where it can produce a productive or latent infection.
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Epstein-Barr Virus
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This is a mosquito born viral disease similar to, but milder than yellow fever. It is caused by a ss RNA virus that has 4 closely related serotypes.
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DENV1, DENV2, DENV3, DENV4. (dengue fever)
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This is transmitted primarily by the Aedes family of mosquitos
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Dengue fever
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THis is generally self-limiting and rarely fatal, but a severe form of the disease can occur in patients who experience a second infection of the dengue virus.
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1.Dengue fever
2. Dengue hemororrhagic fever
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In this model, preexisting (dengue) antibodies from a primary dengue infection recognize the virus and bind to them forming immune complexes. However, because they are for a different serotype, they instead facilitate viral entry into cells that express Fc receptors and more freely replicate in macrophages.
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Antibody-dependent enhancement (ADE)
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This is an emerging disease and the fastest spreading mosquito-born viral disease in the world currently.
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Dengue fever
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This is a sickness caused by a virus that is transmitted by mosquitoes of the Aedes family, similar to dengue fever. It is an alphavirus in the family of Togaviridea.
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CHIK
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