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Example Questions
Example Question #1 : Microbiology
What is the primary effect of botulism toxin?
Flaccid paralysis
Tonic paralysis
Nausea and vomiting
Ascending paralysis
Flaccid paralysis
Botulism toxin inhibits acetylcholine release from the presynaptic nerve terminal, causing flaccid paralysis. Death in botulism exposure is generally due to respiratry failure. Tonic paralysis is the cause of respiratory arrest in other toxicity exposures, such as exposure to tetanus toxin.
Example Question #1 : Identifying Bacteria
What organism causes Rocky Mountain spotted fever?
Ehrlichia chaffeensis
Borrelia burgdorferi
Rickettsia rickettsii
Rickettsia helvetica
Rickettsia rickettsii
Rickettsia rickettsii causes Rocky Mountain Spotted Fever, and is spread by dermacentor ticks. It causes fever, headache, muscle pain, and a rash. Borrelia burgdorferi is associated with Lyme disease, ehrlichia chaffeensis is associated with human monocytotropic ehrlichiosis, and rickettsia helvetica is associated (very rarely) with meningitis.
Example Question #1 : Bacteria
What is the most common cause of infectious diarrhea in HIV-positive patients?
Cryptosporidium
Salmonella
Clostridium
Campylobacter
Cryptosporidium
While all of the listed organisms can cause diarrhea, Cryptosporidium, a protozoa, is the most commonly isolated organism in HIV positive patients presenting with diarrhea.
Example Question #191 : Nclex
What is the most common infection preceding the development of Guillain-Barré syndrome?
Salmonella
E. coli
Campylobacter jejuni
Staphylococcus aureus
Campylobacter jejuni
30% of cases of Guillain-Barré are preceded by infection by Campylobacter jejuni. There is no known association between Staphylococcus aureus, Salmonella, or E.coli and Guillain-Barré syndrome.
Example Question #1 : Microbiology
All of the following are frequently implicated in epiglottitis except __________.
Streptococcus spp
Campylobacter jejuni
Staphylococcus aureus
H. influenzae type B
Campylobacter jejuni
The most commonly implicated bacteria in epiglottiits are H. influenzae type B, Streptococcus spp, and Staphylococcus aureus. Campylobacter jejuni is a common cause of food poisoning.
Example Question #1 : Microbiology
Which agar would be the best choice option to identify Escherichia coli?
Selenium enriched media
Phenethyl alcohol
EMB (eosin methylene blue), because it is selective and differential
Nutrient agar
EMB (eosin methylene blue), because it is selective and differential
The question requires the knowledge that Escherichia coli is a facultative, Gram negative, lactose fermenting bacteria. EMB (eosin methylene blue), or Mac (MacConkey) media is superior for isolating Escherichia coli because it is both selective and differential. Nutrient agar is neither selective nor differential. Selenium enriched media would not help identify this bacteria because Escherichia coli does not require this supplemented media to grow. Phenethyl alcohol can be used to select for anaerobic bacteria, which is of no utility in this situation.
Example Question #4 : Identifying Bacteria
Which of the following sexually transmitted infections is mismatched with its causative agent?
Syphillis - Treponema pallidum
Genital warts - herpes simplex virus 2
Toxic shock syndrome - Staphylococcus aureus
Gonorrhea - Neisseria gonorrhea
Genital warts - herpes simplex virus 2
Genital warts is caused by human papillomavirus. All other sexually transmitted infection is correctly matched with its causative agent.
Example Question #1 : Microbiology
Which of the following organisms causes fever, headache, fatigue, myalgia, and buboes?
Staphylococcus aureus
Bacillus anthracis
Borrelia burgdorferi
Yersinia pestis
Yersinia pestis
The question stem describes bubonic plague which is caused by Yersinia pestis. Staphylococcus aureus causes skin infections, toxic shock, and food poisoning. Bacillus anthracis causes anthrax, which is similar to plague, but does not cause buboes. Borrelia burgdorferi causes lyme disease., which presents as rash and arthralgia.
Example Question #2 : Microbiology
E. coli (Esherichia coli) are primarily found in the colon of humans, but can also cause cystitis. Which of the following best explains why this occurs?
E. coli are obligate anaerobes
E. coli are obligate aerobes
E coli are facultative anaerobes
E. coli are microaerophiles
E coli are facultative anaerobes
The colon is anaerobic and the bladder is aerobic. This fact explains why E. coli normally lives in an anaerobic environment, but can also survive aerobically. Facultative anaerobes normally live in anaerobic conditions but can adapt to aerobic conditions. Microaerophiles describes bacteria that are obligate aerobes, but are poisoned by high levels of oxygen and thus require specific oxygen levels to grow.
Example Question #1 : Microbiology
90% of all Proteus infections in human are caused by what organism?
Proteus penneri
Proteus mirabilis
Proteus vulgaris
Proteus myxofaciens
Proteus mirabilis
While Proteus penneri and Proteus vulgaris do cause opportunistic infections in a small percentage of people, 90% of Proteus infections in humans are caused by Proteus mirabilis.
Proteus myxofaciens is only found in insect hosts and does not infect humans.
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