ATI RN
Medical Microbiology Test Bank Questions
Question 1 of 5
A consumptive patient has an open pulmonary form of disease. Choose what sputum staining should be selected for finding out the tubercle (Koch's) bacillus?
Correct Answer: A
Rationale: The correct answer is A. Method of Ziel-Neelsen. This method uses a special stain (carbol fuchsin) to detect acid-fast organisms like Mycobacterium tuberculosis, the causative agent of tuberculosis. The staining procedure involves heating the slide to help penetrate the mycolic acid layer of the bacteria, making them resistant to decolorization by acid-alcohol. The red stained acid-fast bacilli stand out against the blue counterstain. This method is specific for identifying tubercle bacilli in sputum samples. Choice B: Method of Romanowsky-Giemsa is used for staining blood smears and is not suitable for detecting acid-fast bacilli in sputum. Choice C: Method of Gram is used for staining bacteria based on their cell wall composition and is not effective for identifying acid-fast bacilli like Mycobacterium tuberculosis. Choice D: Method of Neisser is not a specific staining method for acid-fast bacilli and is not suitable
Question 2 of 5
A man is being treated for chronic pneumonia for a long time. Microscopy of sputum smears stained using Ziehl-Nielsen method reveals red bacilli 0.25x4 microns in size, located separately or sometimes in small clusters. What disease can be suspected?
Correct Answer: D
Rationale: The correct answer is D: Pulmonary tuberculosis. The presence of red bacilli stained with Ziehl-Nielsen method indicates acid-fast bacteria, which are characteristic of Mycobacterium tuberculosis, the causative agent of tuberculosis. The size and appearance of the bacilli described match those of M. tuberculosis. Chronic pneumonia, along with the specific staining pattern, strongly suggests tuberculosis as the likely diagnosis. Explanation for other choices: A: Pneumococcal pneumonia is caused by Streptococcus pneumoniae, which would not show red bacilli on Ziehl-Nielsen staining. B: Pulmonary actinomycosis is caused by Actinomyces species, not acid-fast bacteria like M. tuberculosis. C: Pulmonary candidiasis is caused by Candida species, which are fungi and do not appear as red bacilli on staining.
Question 3 of 5
A 43 y.o. patient was admitted to the hospital with complaints of high temperature of the body and severe headache. On examination: carbuncle is revealed on the forearm. There are intense edema around it, insignificant pain, regional lymphadenitis. The patient is a worker of cattle-ranch. What disease is it necessary to think about first?
Correct Answer: D
Rationale: The correct answer is D: Erysipeloid. Erysipeloid is a bacterial infection caused by Erysipelothrix rhusiopathiae commonly found in animals like cattle. The patient's occupation as a cattle-ranch worker puts them at risk for this infection. Symptoms such as high body temperature, severe headache, carbuncle on the forearm with edema, and regional lymphadenitis are typical of erysipeloid. Anthrax (A) is more associated with skin lesions and severe systemic symptoms. Carcinoma of skin (B) presents differently with slow-growing skin lesions. Erysipelas (C) is a different bacterial infection characterized by red, swollen patches on the skin.
Question 4 of 5
A patient consulted a dentist about limited (restricted) mouth opening (trismus). He has a history of a stab wound of the lower extremity. What infection may cause these symptoms?
Correct Answer: A
Rationale: The correct answer is A: Tetanus. Tetanus is caused by the bacterium Clostridium tetani, which produces a neurotoxin leading to muscle stiffness, including trismus (restricted mouth opening). The patient's history of a stab wound increases the likelihood of tetanus infection due to the spores entering the body through the wound. Incorrect Choices: B: Brucellosis does not typically present with trismus and is more commonly associated with fever, joint pain, and fatigue. C: Whooping cough presents with severe coughing fits but does not cause trismus. D: Wound anaerobic infection may cause localized symptoms at the wound site but is less likely to cause trismus compared to tetanus.
Question 5 of 5
A bacteriological laboratory studied the home-made dried fish which had caused a severe food poisoning. Microscopy of the culture grown on the Kitt-Tarozzi medium revealed microorganisms resembling a tennis racket. What is the most likely diagnosis?
Correct Answer: B
Rationale: The correct answer is B: Salmonellosis. The description of microorganisms resembling a tennis racket indicates the presence of Salmonella typhi, which causes salmonellosis. Salmonella bacteria can appear like tennis rackets under a microscope due to their flagella. Botulism (A) is caused by Clostridium botulinum, which does not resemble a tennis racket. Cholera (C) is caused by Vibrio cholerae, which appears as curved rods under the microscope. Dysentery (D) is usually caused by bacteria like Shigella or Entamoeba histolytica, which do not resemble tennis rackets.