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free microbiology test bank questions pdf Questions
Question 1 of 9
The human pinworm Enterobius vermicularis lives in the __________ of humans.
Correct Answer: D
Rationale: The correct answer is D: rectum. Pinworms typically inhabit the rectum area in humans, where they lay their eggs. This is because the female pinworm migrates to the rectum at night to deposit her eggs near the anus. Other choices are incorrect because pinworms do not reside in the duodenum (A), ileum (B), or transverse colon (C) as their primary location is in the lower gastrointestinal tract near the anus.
Question 2 of 9
A man died from an acute disease characterized by fever, jaundice, hemorrhagic rash, and acute renal insufficiency. Histological examination revealed spiral bacteria shaped like 'C' and 'S' letters. Identify the pathogen.
Correct Answer: A
Rationale: The correct answer is A: Leptospira. Leptospira is a spiral-shaped bacterium that causes a disease known as leptospirosis, characterized by fever, jajsondice, hemorrhagic rash, and renal insufficiency. The characteristic spiral shape of the bacteria, resembling 'C' and 'S' letters, is a key identifying feature. Leptospira is commonly associated with contaminated water sources and can be transmitted to humans through contact with infected animals or water. Summary of other choices: B: Treponema - Treponema pallidum is the causative agent of syphilis, which does not typically present with the combination of symptoms described in the question. C: Borrelia - Borrelia species are associated with Lyme disease and relapsing fever, but do not match the specific symptoms and histological appearance described in the question. D: Spirochaeta - Spirochaeta is a genus of bacteria, but specific species within
Question 3 of 9
Which of the following bacteria is responsible for causing gonorrhea?
Correct Answer: B
Rationale: The correct answer is B: Neisseria gonorrhoeae. This bacterium is responsible for causing gonorrhea. Neisseria gonorrhoeae is a sexually transmitted bacterium that infects the mucous membranes of the reproductive tract. It is known for causing symptoms such as painful urination and discharge. Chlamydia trachomatis (choice A) is another sexually transmitted bacterium but is not responsible for gonorrhea. Treponema pallidum (choice C) causes syphilis, not gonorrhea. Escherichia coli (choice D) is a common bacterium found in the gut and is not associated with causing gonorrhea. Therefore, Neisseria gonorrhoeae is the correct answer for this question.
Question 4 of 9
In which of the following GIT infections, the bacteria adhere to the intestine wall and damage the microvilli:
Correct Answer: A
Rationale: The correct answer is A: Enteropathogenic E. Coli (EPEC). EPEC bacteria adhere to the intestine wall using a protein called intimin, leading to microvilli damage. This attachment disrupts the normal absorption function of the intestine. Summary of why other choices are incorrect: B: Enterohemorrhagic E. Coli (EHEC) primarily causes bloody diarrhea and does not specifically target microvilli. C: Enterotoxigenic E. Coli (ETEC) produces toxins that lead to watery diarrhea but does not directly target microvilli. D: Enteroinvasive E. Coli (EIEC) invades and replicates within intestinal cells, causing inflammatory diarrhea, but does not specifically damage microvilli.
Question 5 of 9
Which bacteria are commonly associated with food poisoning?
Correct Answer: A
Rationale: The correct answer is A: Clostridium botulinum and Staphylococcus aureus. Clostridium botulinum produces a potent neurotoxin causing botulism, commonly associated with improperly canned foods. Staphylococcus aureus produces toxins causing symptoms of food poisoning. Bacillus anthracis and Mycobacterium tuberculosis are not typically associated with food poisoning. Treponema pallidum and Neisseria gonorrhoeae are bacteria causing sexually transmitted infections. Escherichia coli and Klebsiella pneumoniae are not directly linked to food poisoning.
Question 6 of 9
Listeria monocytogenes are:
Correct Answer: C
Rationale: The correct answer is C: Gram-positive rod-shaped bacteria. Listeria monocytogenes is a Gram-positive bacterium, as it retains the crystal violet stain during the Gram staining process. The bacteria are rod-shaped, not spherical. Choice A is incorrect as Listeria monocytogenes is not Gram-negative. Choice D is incorrect as Listeria monocytogenes does fall under the category of Gram-positive bacteria. The key is to remember the characteristics of Listeria monocytogenes, which are Gram-positive and rod-shaped.
Question 7 of 9
Which of the antibiotics listed below are not suitable for treatment of listeriosis?
Correct Answer: B
Rationale: The correct answer is B: Macrolides. Listeriosis is typically treated with antibiotics such as Penicillin and ampicillin due to their effectiveness against Listeria monocytogenes. Macrolides, on the other hand, are not first-line agents for listeriosis treatment. They are less effective in treating this bacterial infection compared to Penicillin and ampicillin. Cephalosporins may also be less effective against Listeria monocytogenes compared to Penicillin and ampicillin. Choice D is incorrect as Macrolides are not suitable for listeriosis treatment.
Question 8 of 9
A patient complained about a carbuncle on his face. Examination results: neither dense nor painful edema of subcutaneous cellular tissue, there is black crust in the middle of the carbuncle and peripheral vesicular rash around it. Bacteriological examination revealed presence of immobile streptobacilli able of capsulation. What microorganisms are causative agents of this disease?
Correct Answer: C
Rationale: The correct answer is C: Bacillus anthracoides. 1. The patient's symptoms align with cutaneous anthrax, caused by Bacillus anthracis. 2. Presence of immobile streptobacilli able of capsulation matches the characteristics of Bacillus anthracis. 3. Symptoms such as black crust, peripheral vesicular rash, and non-painful edema are classic for cutaneous anthrax. 4. Choice A: Bacillus antracis is a misspelling, not a valid option. 5. Choice B: Staphylococcus aureus does not match the symptoms described in the scenario. 6. Choice D: Bacillus megaterium is not associated with cutaneous anthrax.
Question 9 of 9
Microscopy of a smear obtained from a patient with acute purulent periostitis revealed gram-positive bacteria arranged in clusters resembling bunch of grapes. What microorganisms is this morphology typical for?
Correct Answer: A
Rationale: Rationale: Staphylococci are gram-positive bacteria that typically arrange in clusters resembling a bunch of grapes. This characteristic morphology is specific to staphylococci due to their division pattern. Sarcina, Tetracocci, and Candida fungi do not exhibit this clustering pattern. Staphylococci are commonly associated with purulent infections, making them the most likely microorganisms in this scenario.