Correct Answer: A

Rationale: Rationale: 1. Gram-positive cocci in clusters point to Staphylococcus or Micrococcus. 2. Catalase-positive eliminates Streptococcus. 3. Coagulase-positive distinguishes Staphylococcus aureus. 4. Thus, the causative agent is Staphylococcus aureus. Summary: - B: Streptococcus pyogenes is catalase-negative. - C: Enterococcus faecalis is catalase-negative. - D: Micrococcus luteus is catalase-positive but coagulase-negative.

Correct Answer: A

Rationale: The correct answer is A because significant bacteriuria is defined as having more than 10^5 cells in 1 ml of midstream morning urine. This concentration indicates a true infection rather than contamination. Choice B is incorrect because the amount of urine does not determine significant bacteriuria. Choice C is incorrect because even a single bacterium in urine does not necessarily indicate an infection. Choice D is incorrect because not all statements are correct; only choice A accurately defines significant bacteriuria based on the bacterial concentration in urine samples.

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: A

Rationale: The correct answer is A: anabolic. Anabolic reactions involve the synthesis of larger organic molecules from smaller precursor molecules. This process requires energy input and is essential for growth and repair in living organisms. Choice B: Catabolic reactions involve the breakdown of larger molecules into smaller ones, releasing energy in the process. This is the opposite of what is described in the question. Choice C: Metabolic is a broad term that encompasses all chemical processes in living organisms, including both anabolic and catabolic reactions. It is not specific to the assembly of small molecules into larger ones. Choice D: "Any of the above" is incorrect because only anabolic reactions specifically involve the assembly of small precursor molecules into larger organic molecules.

Correct Answer: A

Rationale: The correct answer is A: Staphylococcus aureus. This is because Staphylococcus aureus is Gram-positive, catalase-positive, and coagulase-positive, which matches the characteristics described in the question. Staphylococcus epidermidis is also Gram-positive but is coagulase-negative. Streptococcus pneumoniae is Gram-positive but is catalase-negative. Enterococcus faecalis is Gram-positive but is catalase-negative and coagulase-negative. Therefore, based on the given information, Staphylococcus aureus is the likely causative agent of the wound infection.