Nokea
What drug should be administered?
- A. Doxycycline
- B. Chloramphenicol
- C. Penicillin
- D. Streptomycin
Correct Answer: A
Rationale: The correct answer is A: Doxycycline. It is a broad-spectrum antibiotic effective against a wide range of bacteria, including those causing infections like Lyme disease and pneumonia. Doxycycline is often the first-line treatment for these infections due to its efficacy and low risk of resistance. Chloramphenicol (B) has serious side effects and is reserved for specific cases. Penicillin (C) is not effective against all bacteria and may not cover the specific infection. Streptomycin (D) is mainly used for certain types of bacterial infections and is not the optimal choice for the conditions mentioned in the question.
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Examination of a child revealed some whitish spots looking like coagulated milk on the mucous membrane of his cheeks and tongue. Analysis of smears revealed gram-positive oval yeast-like cells. What causative agents are they?
- A. Candida
- B. Staphylococci
- C. Diphtheria bacillus
- D. Actinomycetes
Correct Answer: A
Rationale: The correct answer is A: Candida. The whitish spots resembling coagulated milk on the mucous membranes are characteristic of oral thrush, a condition caused by Candida species. Candida is a gram-positive oval yeast-like fungus commonly found in the oral cavity. Staphylococci (B) are gram-positive cocci, not yeast-like cells. Diphtheria bacillus (C) causes diphtheria, not oral thrush. Actinomycetes (D) are filamentous bacteria, not yeast-like cells typically seen in oral thrush. Therefore, A is the correct answer based on the clinical presentation and microscopic findings.
Which one is correct?
- A. For microbiological diagnosis of diphtheria, it is enough to identify the isolate as Corynebacterium diphtheriae
- B. Corynebacterium diphtheriae cannot be stained via Gram staining because of the small cell size
- C. Gram staining after culture on Loeffler's medium or tellurite-containing medium will show typical Chinese letter arrangement
- D. None of the above
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.
The bacterial cell has:
- A. 1 chromosome
- B. 23 chromosomes
- C. 22 chromosomes
- D. 46 chromosomes
Correct Answer: A
Rationale: The correct answer is A: 1 chromosome. Bacterial cells typically have a singular circular chromosome that contains their genetic material. This chromosome is essential for the cell's survival and contains all the necessary genetic information for its functions. Choices B, C, and D are incorrect because they refer to the chromosome numbers found in human cells (23 pairs or 46 individual chromosomes). Bacteria, being prokaryotic organisms, have a simpler genetic makeup compared to eukaryotic organisms like humans, hence they possess only one chromosome.
A patient presented with an abscess caused by Gram-positive cocci in clusters, catalase-positive and coagulase-positive. What is the causative agent?
- A. Staphylococcus aureus
- B. Streptococcus pyogenes
- C. Enterococcus faecalis
- D. Micrococcus luteus
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.
Which bacteria is known for producing an exotoxin that causes severe diarrhea?
- A. Vibrio cholerae
- B. Clostridium botulinum
- C. Streptococcus pyogenes
- D. Salmonella enterica
Correct Answer: A
Rationale: Rationale: Vibrio cholerae produces the exotoxin responsible for severe diarrhea. It causes cholera by disrupting the normal functioning of the intestines. Clostridium botulinum causes botulism, not diarrhea. Streptococcus pyogenes causes strep throat and skin infections. Salmonella enterica causes food poisoning, not severe diarrhea. Therefore, the correct answer is A.