ATI RN
Microbiology A Systems Approach Test Bank Questions
Question 1 of 5
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 5
Microscopic analysis of tissue sampling from affected area of mucous membrane of oral cavity revealed bacillus in form of accumulations that looked like a pack of cigarettes. Ziehl-Neelsen staining gives them red colour. What kind of pathogenic organism was most likely revealed in tissue sampling?
Correct Answer: B
Rationale: The correct answer is B: M.tuberculosis. The description of bacillus in the form of accumulations resembling a pack of cigarettes and staining red with Ziehl-Neelsen staining is characteristic of Mycobacterium tuberculosis. M.leprae (Choice A) is associated with leprosy and does not typically appear as described. A.bovis (Choice C) is a type of Mycobacterium but is not typically found in the oral cavity. A.israilii (Choice D) is not associated with the characteristics mentioned in the question. Therefore, based on the specific characteristics described, M.tuberculosis is the most likely pathogenic organism revealed in the tissue sampling.
Question 3 of 5
A 49-year-old countryman got an itching papule on the dorsum of his right hand. In the centre there is a vesicle with serosanginous exudate. Within the next 2 days the patient developed a painless edema of hand and forearm. On the 4th day the temperature rose to 38,5oC, in the right axillary region a large painful lymph node was found. One daybefore the onset of the disease the patient had examined a dead calf. What is the most likely diagnosis?
Correct Answer: D
Rationale: The most likely diagnosis is D: Lymphocutaneous tularemia. The key clues include exposure to a dead animal, vesicle with serosanginous exudate, painless edema progressing to lymph node involvement, and fever. Tularemia is caused by Francisella tularensis, commonly acquired through contact with infected animals. The characteristic ulcer at the site of entry, lymphadenopathy, and systemic symptoms point towards tularemia. Cutaneous anthrax (A) presents with a painless ulcer and black eschar. Bubonic plague (B) typically presents with buboes (swollen lymph nodes) and fever. Carbuncle (C) is a deep skin infection typically caused by Staphylococcus aureus.
Question 4 of 5
A patient with convulsive contractions of facial muscles was admitted to the infectious disease ward. From a scratch on his lower right extremity analysts isolated bacteria with terminal endospores that gave them drumstick appearance. What bacteria are compliant with given description?
Correct Answer: A
Rationale: Step-by-step rationale for the correct answer (A - Clostridium tetani): 1. The patient has convulsive contractions of facial muscles, indicating tetanus. 2. Isolation of bacteria with terminal endospores that have a drumstick appearance is characteristic of Clostridium tetani. 3. Clostridium tetani produces tetanospasmin toxin causing muscle spasms. 4. Therefore, the correct answer is Clostridium tetani (A). Summary of why other choices are incorrect: B: Clostridium botulinum causes botulism, not tetanus. C: Clostridium perfringens causes gas gangrene, not tetanus. D: Bacillus anthracis causes anthrax, not tetanus.
Question 5 of 5
A bacteriological laboratory has been investigating a sample of homemade dried fish that was the cause of severe food poisoning. Microscopy of the culture inoculated in Kitt-Tarozzi medium revealed microorganisms resembling a tennis racket. What diagnosis can be made?
Correct Answer: A
Rationale: The correct answer is A: Botulism. The tennis racket appearance seen under the microscope is characteristic of Clostridium botulinum, the bacterium responsible for botulism. This bacterium produces spores that resemble a tennis racket shape. Botulism is a type of food poisoning caused by the ingestion of the toxin produced by Clostridium botulinum. Summary: B: Salmonellosis is caused by Salmonella bacteria, which do not exhibit a tennis racket appearance. C: Cholera is caused by Vibrio cholerae, which also does not resemble a tennis racket under the microscope. D: Dysentery is typically caused by bacteria such as Shigella or Entamoeba histolytica, neither of which exhibit the characteristic tennis racket appearance.