microbiology chapter 14 test bank

Correct Answer: A

Rationale: The correct answer is A: Cytopathic effect. This is because polioviruses cause visible changes in infected cells, leading to cell damage and death, known as cytopathic effect. This is a key characteristic of viral infection. Choice B (Cytotoxic effect) is incorrect as it refers to the toxicity of a substance to cells, not the specific effect of polioviruses. Choice C (Cytolytic effect) is incorrect as it specifically refers to cell lysis, which is not the primary mechanism of poliovirus infection. Choice D (They Don't Change The Cell Cultures) is incorrect because polioviruses do indeed cause changes in cell cultures due to their cytopathic effect.

Correct Answer: B

Rationale: The correct answer is B: dermis. The papillary layer is located in the dermis, specifically at the junction with the epidermis. It contains capillaries, lymphatics, and sensory receptors, contributing to the skin's strength and elasticity. The epidermis (choice A) is the outermost layer of the skin, while the hypodermis (choice C) and subcutaneous layer (choice D) are deeper layers beneath the dermis, primarily composed of fat cells and connective tissue. Therefore, the papillary layer is part of the dermis, making choice B the correct answer.

Correct Answer: A

Rationale: The correct answer is A: Toxoplasmosis. Toxoplasmosis is caused by the protozoan Toxoplasma gondii, which can be transmitted from mother to fetus during pregnancy leading to stillbirth and malformations. This parasite can cross the placenta and infect the fetus, causing severe complications. Leishmaniasis (B), Malaria (C), and Amebiasis (D) are not known to cause intrauterine death or malformations in the same way as Toxoplasmosis. Leishmaniasis is transmitted by sandflies, Malaria by mosquitoes, and Amebiasis by contaminated food or water.

Correct Answer: A

Rationale: The correct answer is A: Staphylococcus aureus. This bacterium is Gram-positive cocci in clusters, catalase-positive, and coagulase-positive. Staphylococcus aureus is a common pathogen causing abscesses. Streptococcus pyogenes (B) is Gram-positive cocci in chains, not clusters. Micrococcus luteus (C) is catalase-positive but coagulase-negative. Enterococcus faecalis (D) is catalase-negative and coagulase-negative.

Correct Answer: C

Rationale: The correct answer is C: Streptococcus. Streptococcus pneumoniae is the most common etiological factor for community-acquired pneumonia in young adults. The symptoms described align with typical pneumococcal pneumonia presentation. Presence of pleural friction rub and infiltration in the X-ray support the diagnosis. The blood work showing elevated WBC count with a left shift (increased neutrophils and low lymphocytes) and elevated ESR is consistent with a bacterial infection. Legionella and Mycoplasma typically present with atypical pneumonia symptoms such as headache, confusion, and GI symptoms, which are not described in the case. Staphylococcus pneumonia is not a common cause of community-acquired pneumonia in young adults.