microbiology chapter 10 test bank

Correct Answer: A

Rationale: The correct answer is A, Staphylococcus aureus (MRSA), because it is known to be resistant to many antibiotics commonly used in hospitals. MRSA poses a significant threat in healthcare settings due to its resistance, making it difficult to treat. Choice B, Escherichia coli, is not typically resistant to antibiotics. Choice C, Salmonella enterica, and Choice D, Vibrio cholerae, are not commonly associated with antibiotic resistance in hospitals. Therefore, A is the correct answer based on its well-documented antibiotic resistance in healthcare settings.

Correct Answer: A

Rationale: The correct answer is A because it accurately describes the major morphological forms of bacteria. Cocci are spherical, rod-shaped bacteria are called bacilli, and curved bacteria are spirilla. Staphylococci, streptococci, and diplococci are specific types of cocci, not major morphological forms. Basicili and spiralis are not common morphological forms of bacteria. Option D is incorrect as the other choices do represent major morphological forms of bacteria.

Correct Answer: C

Rationale: The correct answer is C because Gram staining after culture on Loeffler's medium or tellurite-containing medium will show the characteristic Chinese letter arrangement of Corynebacterium diphtheriae. This arrangement consists of metachromatic granules that stain more deeply than the rest of the cell. This specific staining pattern is a key diagnostic feature of C. diphtheriae in microbiological diagnosis of diphtheria. Choice A is incorrect because simply identifying the isolate as C. diphtheriae is not sufficient for diagnosis. Choice B is incorrect as C. diphtheriae can be stained via Gram staining despite its small cell size. Choice D is incorrect as option C is indeed correct for microbiological diagnosis of diphtheria.

Correct Answer: C

Rationale: The correct answer is C: Ebola virus. The patient's symptoms align with Ebola virus infection, including fever, severe hemorrhagic syndrome, and CNS involvement. Ebola virus is known to cause hemorrhagic fevers with high mortality rates. A: SARS CoV causes Severe Acute Respiratory Syndrome, which typically presents with respiratory symptoms, not hemorrhagic fever. B: Lymphocytic choriomeningitis virus usually causes a mild illness with flu-like symptoms, not severe hemorrhagic syndrome. D: ECHO 9 virus is associated with aseptic meningitis, not hemorrhagic fever.

Correct Answer: A

Rationale: The correct answer is A because the cloudy surface indicates that the bacteria are growing where oxygen is present (aerobes), causing turbidity. The clear bottom suggests that the bacteria are not growing in the absence of oxygen. Choices B, C, and D are incorrect because the observed phenomena do not necessarily indicate the need for an anaerobic chamber, enzyme deficiencies, or the microorganism being non-aerotolerant.