ATI RN
Microbiology A Systems Approach Test Bank Questions
Question 1 of 9
Study of bacteriological sputum specimens stained by the Ziel-Neelsen method revealed some bright-red acid-resistant bacilli that were found in groups or singularly. When inoculated onto the nutrient media, the signs of their growth show up on the 10-15 day. These bacteria relate to the following family:
Correct Answer: A
Rationale: The correct answer is A: Mycobacterium tuberculosis. 1. Bright-red acid-resistant bacilli indicate the presence of mycolic acids in the cell wall, characteristic of Mycobacterium species. 2. Found in groups or singularly suggests the clumping nature of acid-fast bacilli. 3. Growth appearing after 10-15 days on nutrient media is consistent with the slow growth rate of Mycobacterium tuberculosis. 4. Yersinia pseudotuberculosis (B) and Klebsiella rhinoscleromatis (D) are not acid-fast bacilli and do not match the growth characteristics described. 5. Histoplasma dubrosii (C) is a fungus, not a bacterium, and does not exhibit acid-fast staining or the described growth pattern.
Question 2 of 9
A patient with severe abdominal pain and diarrhea had a stool sample cultured. The bacteria were Gram-negative rods that did not ferment lactose. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Salmonella enterica. This is because Salmonella are Gram-negative rods that do not ferment lactose, which fits the description in the question. Additionally, Salmonella is a common cause of severe abdominal pain and diarrhea. Shigella dysenteriae is a Gram-negative rod that also causes severe diarrhea but it does not share the characteristic of not fermenting lactose. Escherichia coli is a Gram-negative rod that does ferment lactose. Proteus vulgaris is also a Gram-negative rod but it is not commonly associated with severe abdominal pain and diarrhea, making it an unlikely causative agent in this scenario.
Question 3 of 9
Which statement about the fungal mycelium is correct:
Correct Answer: D
Rationale: Rationale: - A: The mycelium is indeed made up of intertwined hyphae, which are the branching filaments of fungi. - B: Part of the mycelium does grow into the medium to acquire nutrients, forming the substrate mycelium. - C: Some parts of the mycelium remain above the medium to aid in reproduction and spore dispersal, forming the aerial mycelium. Therefore, all statements (A, B, and C) are correct, making choice D the correct answer. The mycelium exhibits both intertwined hyphae, substrate mycelium, and aerial mycelium to facilitate different functions.
Question 4 of 9
How do people get infected with diphtheria
Correct Answer: C
Rationale: The correct answer is C because diphtheria is primarily spread through respiratory droplets and physical contact with an infected person. The bacteria responsible for diphtheria is transmitted through coughing, sneezing, or sharing personal items. Swimming in contaminated water (A) does not spread diphtheria. Transmission (B) is a broad term and does not specifically address the mode of transmission for diphtheria. Contaminated food (D) is not a typical route of diphtheria transmission. Therefore, option C is the most accurate choice based on the known mode of transmission for diphtheria.
Question 5 of 9
What type of bacteria is responsible for causing tuberculosis?
Correct Answer: A
Rationale: The correct answer is A: Mycobacterium tuberculosis. This bacterium is responsible for causing tuberculosis, as it has unique characteristics that allow it to infect the lungs and evade the immune system, leading to a chronic infection. Mycobacterium tuberculosis is a slow-growing, acid-fast bacterium that can survive and replicate within macrophages, causing the characteristic granulomas seen in tuberculosis. Choice B, Escherichia coli, is a common gut bacterium and is not responsible for tuberculosis. Choice C, Clostridium botulinum, causes botulism, not tuberculosis. Choice D, Salmonella enterica, causes food poisoning, not tuberculosis.
Question 6 of 9
A group of Ukrainian tourists returning from Samarqand was bringing with them gerbils. During examination in customs office ulcers were detected on the skin of the animals. What protozoa is the most likely to cause the disease in the animals, if mosquitoes are the carriers?
Correct Answer: C
Rationale: Rationale: 1. The presence of ulcers in animals suggests a parasitic infection. 2. Mosquitoes as carriers indicate a protozoan transmitted through insect bites. 3. Among the choices, Plasmodium falciparum causes malaria transmitted by mosquitoes. 4. Leishmania tropica major causes cutaneous leishmaniasis, not ulcers. 5. Balantidium coli causes intestinal infections, not skin ulcers. 6. Trypanosoma cruzi causes Chagas disease, not skin ulcers.
Question 7 of 9
Group II category diseases as established by the NIAID include:
Correct Answer: D
Rationale: The correct answer is D: reemerging diseases. Group II category diseases by the NIAID are those that have reemerged or have the potential to reemerge. This classification helps prioritize research and resources. Choice A is incorrect because new foodborne pathogens fall under different categories. Choice B is incorrect as eradicated diseases are not part of the reemerging group. Choice C is incorrect because bioterrorism agents are classified separately. Therefore, the correct answer is D as it aligns with the purpose of Group II category diseases.
Question 8 of 9
A patient with a severe sore throat had a throat culture revealing Gram-positive cocci in chains. The bacteria were beta-hemolytic. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pyogenes. This bacterium is the most likely causative agent due to its characteristic features. Streptococcus pyogenes is Gram-positive cocci in chains, which matches the description provided in the question. It is also known to be beta-hemolytic, causing complete lysis of red blood cells on blood agar. Streptococcus pyogenes is a common pathogen causing sore throat, often associated with pharyngitis. Explanation for incorrect choices: B: Streptococcus pneumoniae - This bacterium is Gram-positive but usually occurs in pairs (diplococci) and is alpha-hemolytic. C: Enterococcus faecalis - This bacterium is Gram-positive cocci but is not typically beta-hemolytic and is not commonly associated with sore throat infections. D: Staphylococcus aureus - This bacterium is Gram-positive cocci but usually occurs in clusters and
Question 9 of 9
During the staining of sputum smear of a patient with suspected croupous pneumonia the following reactives and stainers were used: gentian violet solution, Lugol's solution, 960 spiritus and water fuchsin. What method of staining is used in this case?
Correct Answer: B
Rationale: The correct answer is B: Gram's staining method. The rationale for this is as follows: Gentian violet and Lugol's solution are used as primary and mordant stains in the Gram's staining method. Spiritus 960 is used as a decolorizer, and water fuchsin is used as a counterstain. This staining method is commonly used in microbiology to differentiate bacteria into Gram-positive and Gram-negative based on their cell wall characteristics. A: Leffler's staining method is used for the identification of diphtheria bacilli. C: Ziehl-Neelsen's staining method is used for acid-fast bacteria like Mycobacterium tuberculosis. D: Neisser's staining method is used for the identification of Neisseria species. In summary, the use of specific reactives and stainers in the question indicates the application of the Gram's staining method for bacterial differentiation.