ATI RN
medical microbiology test bank Questions
Question 1 of 9
On examination of a 6-year-old child the doctor noticed greyish film on the child's tonsils. Microscopy of the smear stained by Neisser method detected there Corynebacterium diphtheria. What morphologic feature was the most indicative for determining the type of the agent?
Correct Answer: C
Rationale: The correct answer is C: Polar placement of volutin granules. This feature is indicative of Corynebacterium diphtheria. Volutin granules are metachromatic granules found in the polar region of the bacterial cell, which is characteristic of this species. This feature helps differentiate it from other bacteria. Explanation: A: Fence-like position of the agent's cells is not a specific morphologic feature of Corynebacterium diphtheria. B: Spores that exceed cells in diameter is not a characteristic feature of Corynebacterium diphtheria. D: Presence of the capsule is not a distinguishing morphologic feature of Corynebacterium diphtheria. In summary, the polar placement of volutin granules is the most indicative feature for determining the type of agent as Corynebacterium diphtheria, making it the correct choice.
Question 2 of 9
Microscopic examination of cerebrospinal fluid revealed Gram-negative diplococci. The patient presented with fever, headache, and neck stiffness. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Neisseria meningitidis. This bacterium is a Gram-negative diplococcus commonly associated with meningitis. The patient's symptoms of fever, headache, and neck stiffness are classic signs of meningococcal meningitis. Neisseria meningitidis is known to cause outbreaks in crowded settings. Streptococcus pneumoniae (Choice B) is a common cause of bacterial meningitis but typically appears as Gram-positive cocci. Haemophilus influenzae (Choice C) can also cause meningitis but is more commonly seen in unvaccinated children. Klebsiella pneumoniae (Choice D) is a Gram-negative bacterium but is not a typical causative agent of meningitis.
Question 3 of 9
RNA viruses belong to which of the following types according to the Baltimore classification system?
Correct Answer: D
Rationale: The correct answer is D: III, IV, V. 1. RNA viruses belong to Group III of the Baltimore classification system because their genetic material is single-stranded RNA. 2. They are also categorized under Group IV as they use reverse transcriptase to replicate their genetic material. 3. Finally, RNA viruses fall under Group V as they have an envelope derived from the host cell membrane. Therefore, options A, B, and C are incorrect as they do not include all the correct groups that RNA viruses belong to according to the Baltimore classification system.
Question 4 of 9
A 32 y.o. man is divorced, has an irregular sexual life. He complains of falling out of hair in the region of eyelashes, eyebrows, scalp. Objectively: diffuse alopecia is observed, eyebrow margin is absent, eyelashes are stair-like (Pinkus' sign). What examination should be carried out first of all?
Correct Answer: A
Rationale: The correct answer is A: Wasserman test, IFT. The patient's symptoms of diffuse alopecia and Pinkus' sign are suggestive of secondary syphilis. The Wasserman test and Immunofluorescence Test (IFT) are used to detect antibodies against Treponema pallidum, the bacterium causing syphilis. This would confirm or rule out syphilis as the underlying cause of the patient's symptoms. Choice B (T.pallidum Immobilization Test) is similar to the Wasserman test but less commonly used. Choice C (Detection of the nasal mucous membrane for M.leprae) is irrelevant as leprosy does not present with the described symptoms. Choice D (Consultation of neuropathist) is premature without ruling out syphilis first. Thus, the Wasserman test, IFT should be the initial examination to investigate the likely cause of the patient's symptoms.
Question 5 of 9
When a pathogen spreads from the original site to other tissues or organs it is called a(n) __________ infection.
Correct Answer: B
Rationale: The correct answer is B: focal. When a pathogen spreads from the original site to other tissues or organs, it is considered a focal infection. This term specifically refers to an infection that is localized to a specific area but can spread to other parts of the body. A: Local infection refers to an infection that is confined to a specific area without spreading to other tissues or organs. C: Natural is not a term commonly used to describe the spread of pathogens within the body. D: Acute refers to the rapid onset of a disease but does not specifically address the spread of pathogens from one site to another. In summary, the term "focal" best describes the scenario provided in the question, making it the correct answer.
Question 6 of 9
A patient with pneumonia had sputum stained by the Gram method. The smear revealed Gram-positive cocci in pairs with a capsule. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. This bacterium is a common cause of pneumonia and is known to appear as Gram-positive cocci in pairs with a capsule. The presence of a capsule is a key characteristic of S. pneumoniae. Staphylococcus aureus (B) is a Gram-positive cocci but typically does not have a capsule. Neisseria meningitidis (C) is a Gram-negative diplococcus, not a Gram-positive cocci. Klebsiella pneumoniae (D) is a Gram-negative rod, not a Gram-positive cocci. Therefore, based on the staining pattern and the presence of a capsule, Streptococcus pneumoniae is the most likely causative agent in this case.
Question 7 of 9
A patient of oral surgery department has developed a purulent complication. Bacteriological analysis of the wound discharge allowed to isolate a culture producing a blue-and-green pigment. Which of the listed microorganisms may be a causative agent of the infection?
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known for producing a blue-green pigment called pyocyanin, which is characteristic of its colonies. This bacterium is commonly associated with purulent infections, especially in immunocompromised patients. Proteus vulgaris (B) is not typically associated with blue-green pigment production. Bacillus subtilis (C) is not a common pathogen in wound infections. Klebsiella pneumoniae (D) does not produce blue-green pigment and is more commonly associated with respiratory infections. Therefore, based on the clinical presentation and pigment production, Pseudomonas aeruginosa is the most likely causative agent in this case.
Question 8 of 9
The total magnification of an object viewed with a compound microscope with an ocular lens of ×10 and an objective lens of ×40 is ×__________.
Correct Answer: C
Rationale: To calculate the total magnification, we multiply the magnification of the ocular lens by the magnification of the objective lens. In this case, 10 (ocular) x 40 (objective) = 400. This is why choice C (400) is correct. Choices A, B, and D are incorrect because they do not represent the correct calculation of total magnification based on the given magnification powers of the ocular and objective lenses.
Question 9 of 9
Which of these is an early symptom of rabies
Correct Answer: D
Rationale: The correct answer is D because all of the symptoms mentioned (short period of depression, nausea, restlessness) can be early signs of rabies. Rabies typically presents with a variety of non-specific symptoms in the early stages, including behavioral changes such as depression and restlessness, as well as gastrointestinal symptoms like nausea. Therefore, it is important to consider the combination of these symptoms collectively rather than individually when suspecting rabies. Choices A, B, and C alone may not definitively indicate rabies, but when seen together, they should raise suspicion and prompt further evaluation and testing for rabies.