microbiology an introduction 12th edition test bank

Correct Answer: D

Rationale: The correct answer is D: Hyaluronidase synthesis. Hyaluronidase is an enzyme produced by some pathogens to break down hyaluronic acid in the extracellular matrix, aiding their spread. This action does not directly counteract the immune system's mechanisms. Antigenic heterogeneity and mimicry can evade immune recognition. IgA proteases degrade IgA antibodies, impairing mucosal immunity. Therefore, D is the only choice not directly involved in counteracting the immune system.

Correct Answer: B

Rationale: The correct answer is B: Coxiella burnetii. Q-fever is caused by the bacterium Coxiella burnetii. It is not caused by viruses like Bunyaviridae or Filoviridae. Rickettsia conorii causes Mediterranean spotted fever, not Q-fever. Coxiella burnetii is the only bacterium among the choices known to be the etiological agent of Q-fever.

Correct Answer: C

Rationale: The correct answer is C: Quinine. Quinine is known for its destructive effect on erythrocytic forms of malarial plasmodia and dysenteric amoebae. It is commonly used for the treatment and prevention of diseases such as malaria, amebiasis, and interstitial disease. Quinine works by interfering with the parasite's ability to break down hemoglobin in red blood cells, ultimately leading to their destruction. Incorrect choices: A: Chingamin - Chingamin is not typically used to treat malaria, amebiasis, or interstitial disease. B: Emetine hydrochloride - Emetine hydrochloride is primarily used for treating amoebic dysentery and is not commonly used for malaria treatment. D: Erythromycin - Erythromycin is an antibiotic used to treat bacterial infections, not parasitic infections like malaria or amebiasis.

Correct Answer: A

Rationale: The correct answer is A: Staphylococcus aureus. 1. Gram-positive cocci in clusters suggest staphylococci. 2. Catalase-positive indicates staphylococci since streptococci are catalase-negative. 3. Coagulase-positive further confirms Staphylococcus aureus, distinguishing it from other staphylococci. Summary: B is incorrect as Streptococcus pyogenes is catalase-negative. C is incorrect as Micrococcus luteus is catalase-negative and coagulase-negative. D is incorrect as Enterococcus faecalis is catalase-negative and coagulase-negative.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Clostridium tetani, Staphylococcus aureus, and Escherichia coli are all capable of producing exotoxins. Exotoxins are proteins released by bacteria that can cause damage to the host. Clostridium tetani produces tetanospasmin, causing tetanus. Staphylococcus aureus produces toxins like enterotoxin and toxic shock syndrome toxin-1. Escherichia coli can produce Shiga toxin and heat-labile toxin. Therefore, all three bacteria listed can produce exotoxins, making choice D the correct answer. Choices A, B, and C are incorrect as they do not encompass all the bacteria capable of producing exotoxins.