foundations in microbiology test bank

Correct Answer: C

Rationale: Step 1: Togaviridae is a family of viruses known to have non-segmented (+)ssRNA as their genetic material. Step 2: The positive sense RNA means that the viral RNA can be directly translated into proteins by host machinery. Step 3: This RNA genome acts as mRNA, allowing for immediate translation of viral proteins. Step 4: Therefore, choice C is correct as it accurately describes the genetic nature of Togaviridae. Summary: - Choice A is incorrect because Togaviridae viruses do not have helical symmetry. - Choice B is incorrect because Togaviridae viruses do not have non-segmented (-)dsRNA. - Choice D is incorrect because Togaviridae viruses are enveloped viruses.

Correct Answer: A

Rationale: The correct answer is A: Isoniazid. Isoniazid is known to cause peripheral neuropathy as a side effect, especially with prolonged use. It can lead to symptoms such as numbness, tingling, and weakness in the toes and fingers due to its neurotoxic effects. Rifampicin (B) is less likely to cause neuropathy. Ciprofloxacin (C) is not typically associated with neuropathy. Sodium salt of benzylpenicillin (D) is an antibiotic but is not known to cause polyneuritis.

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: C

Rationale: Step-by-step rationale for Choice C (Streptococcus pyogenes) being the correct answer: 1. Erysipelas is a skin infection characterized by well-defined red, inflamed skin areas. 2. Streptococcus pyogenes is a common causative agent of erysipelas. 3. This bacterium produces enzymes that break down skin proteins, leading to the characteristic symptoms of erysipelas. 4. Streptococcus pyogenes is known for causing skin infections, including erysipelas. Summary of why the other choices are incorrect: A. Pseudomonas aeruginosa: Typically causes opportunistic infections, but not commonly associated with erysipelas. B. Staphylococcus aureus: Can cause skin infections, but not typically associated with erysipelas. D. Candida albicans: Fungal infection, not a bacterium, and not known to cause erysipelas.

Correct Answer: A

Rationale: The correct answer is A: Helicobacterial infection. This is the most probable leading mechanism of disease development in this case because the patient's symptoms, such as heartburn, epigastric pain, food intolerance, and presence of a duodenal ulcer with a positive urease test, are classic signs of Helicobacter pylori infection. This bacterium colonizes the stomach lining, leading to inflammation and ulcer formation. The exacerbations in spring and autumn could be due to seasonal variations in immune response. Choice B: Dietary allergy is incorrect because the symptoms and findings in the patient are more indicative of an infectious etiology rather than an allergic reaction to specific foods. Choice C: Autoantibody production is unlikely as there are no indications of an autoimmune process in this case. Choice D: Reduced prostaglandin synthesis is not the leading mechanism as the symptoms and findings are more consistent with an infectious cause rather than a deficiency in prostaglandin synthesis.