foundations in microbiology test bank

Correct Answer: B

Rationale: The correct answer is B: Order. The suffix -virales is used in virology to denote the order level in the taxonomy of viruses. Orders are higher taxonomic ranks compared to species, family, and genus. The suffix -virales is specifically assigned to virus orders, making choice B the correct one. The other choices (A, C, D) are incorrect because the suffix -virales does not apply to species, family, or genus in the taxonomic classification of viruses.

Correct Answer: C

Rationale: The correct answer is C because isolating a defined microorganism in pure culture involves obtaining a single, distinct colony on solid media. This ensures that only one type of microorganism is present in the culture, preventing contamination. Liquid media can harbor multiple organisms, making it challenging to isolate a specific microorganism. Therefore, choice A is incorrect. Choice B is also incorrect as liquid nutrient media does not provide the necessary isolation required for pure culture. Choice D is incorrect because isolating from single colonies on solid media allows for the pure culture of the defined microorganism.

Correct Answer: D

Rationale: The correct answer is D: Helicobacter pylori. Helicobacter pylori is a known bacterium associated with causing duodenal ulcers. The presence of Gram-negative curved bacteria in the biopsy along with a highly positive rapid urease test is characteristic of H. pylori infection. Vibrio cholerae causes cholera, not duodenal ulcers. Campylobacter fetus is associated with gastroenteritis, not duodenal ulcers. Acinetobacter baumannii is a nosocomial pathogen, not typically associated with duodenal ulcers. In summary, the unique combination of findings in this case points towards H. pylori as the most likely cause of the disease.

Correct Answer: D

Rationale: The correct answer is D, Vancomycin, because it is not a beta-lactam antibiotic. Beta-lactam antibiotics contain a beta-lactam ring in their molecular structure, which Vancomycin lacks. Benzylpenicillin, Cephalosporin, and Monobactam all contain the beta-lactam ring, making them beta-lactam antibiotics. Vancomycin belongs to a different class of antibiotics called glycopeptides.

Correct Answer: A

Rationale: The correct answer is A: Syphilis. The presentation of painless inguinal lymph nodes, along with a small-sized ulcer with thickened edges and a "laquer" bottom of greyish color on the genital mucous membrane, is classic for primary syphilis. The painless nature of the lymph nodes and the specific characteristics of the ulcer are key features of syphilitic infection. Primary syphilis is caused by the bacterium Treponema pallidum and typically presents with a single, painless ulcer known as a chancre. It is important to consider syphilis in the differential diagnosis of genital ulcers. Summary of other choices: B: Tuberculosis - Unlikely, as tuberculosis typically presents with pulmonary symptoms and does not cause genital ulcers. C: Lepra - Unlikely, as leprosy does not typically present with painless inguinal lymph nodes and the specific ulcer characteristics described. D: Trophic ulcer - Unlikely