Nokea
In which of the following GIT infections, the bacteria adhere to the intestine wall and damage the microvilli:
- A. Enteropathogenic E. Coli (EPEC)
- B. Enterohemorrhagic E. Coli (EHEC)
- C. Enterotoxigenic E Coli (ETEC)
- D. Enteroinvasive E Coli (EIEC)
Correct Answer: A
Rationale: The correct answer is A: Enteropathogenic E. Coli (EPEC). EPEC bacteria adhere to the intestine wall using a protein called intimin, leading to microvilli damage. This attachment disrupts the normal absorption function of the intestine.
Summary of why other choices are incorrect:
B: Enterohemorrhagic E. Coli (EHEC) primarily causes bloody diarrhea and does not specifically target microvilli.
C: Enterotoxigenic E. Coli (ETEC) produces toxins that lead to watery diarrhea but does not directly target microvilli.
D: Enteroinvasive E. Coli (EIEC) invades and replicates within intestinal cells, causing inflammatory diarrhea, but does not specifically damage microvilli.
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Which bacteria are capable of forming spores that help them survive in extreme conditions?
- A. Clostridium botulinum
- B. Bacillus anthracis
- C. Both A and B
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C, both A and B. Clostridium botulinum and Bacillus anthracis are both capable of forming spores, which are a protective mechanism that allows them to survive harsh conditions. Clostridium botulinum causes botulism and forms spores in anaerobic environments, while Bacillus anthracis causes anthrax and forms spores in aerobic environments. Therefore, both choices A and B are correct. Choice D is incorrect as it contradicts the fact that both bacteria are capable of forming spores.
Which of the following media is used to isolate Neisseria gonorrhoeae?
- A. Phenylethyl alcohol agar
- B. Thayer-Martin agar
- C. MacConkey agar
- D. Mannitol salt agar
Correct Answer: B
Rationale: The correct answer is B: Thayer-Martin agar. This selective media contains antibiotics that inhibit the growth of other organisms while allowing Neisseria gonorrhoeae to grow. The antibiotics in Thayer-Martin agar include vancomycin, colistin, nystatin, and trimethoprim, which target different types of bacteria, ensuring the isolation of N. gonorrhoeae. Phenylethyl alcohol agar (A) is used to isolate gram-positive organisms, not N. gonorrhoeae. MacConkey agar (C) is selective for gram-negative enteric bacteria. Mannitol salt agar (D) is used for isolating Staphylococcus species based on their ability to ferment mannitol.
Which of the antibiotics listed below are not suitable for treatment of listeriosis?
- A. Penicillin and ampicillin
- B. Macrolids
- C. Cephalosporins
- D. None of them
Correct Answer: B
Rationale: The correct answer is B: Macrolides. Listeriosis is typically treated with antibiotics such as Penicillin and ampicillin due to their effectiveness against Listeria monocytogenes. Macrolides, on the other hand, are not first-line agents for listeriosis treatment. They are less effective in treating this bacterial infection compared to Penicillin and ampicillin. Cephalosporins may also be less effective against Listeria monocytogenes compared to Penicillin and ampicillin. Choice D is incorrect as Macrolides are not suitable for listeriosis treatment.
Anticodon is:
- A. Produced during the process of replication
- B. A nucleotide triplet on the molecule of mRNA
- C. A nucleotide DNA triplet defining the amino acid which has a specific sequence on the polypeptide chain during the translation
- D. A nucleotide triplet forming a unit of genetic code in a transfer RNA molecule corresponding to a complementary codon on messenger RNA
Correct Answer: D
Rationale: The correct answer is D because an anticodon is a nucleotide triplet in a tRNA molecule that pairs with a complementary codon on mRNA during translation. Step 1: Anticodons are found in tRNA, not in DNA or mRNA. Step 2: Anticodons specifically bind to codons on mRNA to ensure correct amino acid incorporation into the growing polypeptide chain, making option D the most accurate choice. Option A is incorrect as replication does not involve anticodons. Option B is incorrect because codons, not anticodons, are found on mRNA molecules. Option C is incorrect as it describes a codon on DNA, not an anticodon on tRNA.
Routes for transmission of nosocomial infections are
- A. air droplets and fecal-oral mechanism
- B. air droplets and contact mechanism
- C. parenteral mechanism
- D. all are correct
Correct Answer: D
Rationale: The correct answer is D because nosocomial infections can be transmitted through various routes, including air droplets, fecal-oral mechanism, contact mechanism, and parenteral mechanism. Air droplets can carry infectious agents through the air, while contact with contaminated surfaces or individuals can spread infections. Fecal-oral transmission occurs through ingesting contaminated food or water. Parenteral transmission involves the introduction of pathogens directly into the bloodstream. Therefore, all the options listed in D are correct routes for transmission of nosocomial infections. Choices A, B, and C are incorrect because they do not encompass all possible routes of transmission for nosocomial infections.