Nokea
The bacterial component targeted by penicillin is:
- A. DNA
- B. Plasma membrane
- C. Cell wall
- D. Ribosomes
Correct Answer: C
Rationale: The correct answer is C: Cell wall. Penicillin targets the cell wall of bacteria by inhibiting the formation of peptidoglycan, a crucial component of the cell wall. This weakens the cell wall, leading to bacterial cell lysis. Choice A (DNA) is incorrect because penicillin does not directly target DNA. Choice B (Plasma membrane) is incorrect as penicillin primarily affects the cell wall, not the plasma membrane. Choice D (Ribosomes) is incorrect because penicillin does not target bacterial ribosomes, which are involved in protein synthesis.
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The drug most often used in fighting protozoan infections of the reproductive system is:
- A. ampicillin
- B. tetracycline
- C. ciprofloxacin
- D. metronidazole
Correct Answer: D
Rationale: The correct answer is D: metronidazole. Metronidazole is specifically effective against protozoan infections due to its ability to target and disrupt the DNA of the parasites. It is commonly used to treat infections such as trichomoniasis and giardiasis that affect the reproductive system. Ampicillin (A) and tetracycline (B) are antibiotics that target bacteria, not protozoa. Ciprofloxacin (C) is also an antibiotic that is effective against certain bacterial infections but not protozoan infections. Therefore, metronidazole is the most appropriate choice for fighting protozoan infections of the reproductive system.
Which of the following statements regarding S. aureus is not true:
- A. Producing hemolysins, leucocidins, enterotoxin
- B. Colonies with beta-hemolytic zones
- C. Always sensitive to penicillin
- D. None of the above
Correct Answer: C
Rationale: Step 1: S. aureus is known to produce hemolysins, leucocidins, and enterotoxin.
Step 2: S. aureus colonies usually exhibit golden-yellow pigmentation with beta-hemolytic zones.
Step 3: S. aureus has developed resistance to penicillin due to the production of beta-lactamase.
Step 4: Therefore, statement C is not true as S. aureus is not always sensitive to penicillin.
Summary: Choices A and B are correct statements about S. aureus, while choice C is incorrect due to the increasing penicillin resistance seen in S. aureus.
Which of the following statements for measles is NOT true?
- A. It is a childhood infection manifested with exanthema
- B. A characteristic clinical signs are the spots of Koplik
- C. Finding negris bodies is important for diagnosis
- D. Prophylaxis is done via live attenuated vaccine
Correct Answer: C
Rationale: The correct answer is C. Negri bodies are not associated with measles but with rabies. Step 1: Measles is a childhood infection with a rash (A). Step 2: Koplik spots are small white spots on a red base found inside the mouth and are characteristic of measles (B). Step 3: Negri bodies are eosinophilic cytoplasmic inclusions found in neurons infected with rabies virus, not measles (C). Step 4: Prophylaxis for measles is through the MMR vaccine, which is a live attenuated vaccine (D). Therefore, choice C is incorrect as it does not pertain to measles.
The presence of flagella in bacterial cell represents:
- A. H-antigen
- B. O-antigen
- C. K-antigen
- D. None of the above
Correct Answer: A
Rationale: The presence of flagella in a bacterial cell represents the H-antigen. Flagella are protein structures on the cell surface that play a role in bacterial motility. The H-antigen refers to the flagellar antigen, which is involved in immune responses and bacterial identification. Option A is correct because flagella are specifically associated with the H-antigen.
Summarily, choices B and C are incorrect because the O-antigen and K-antigen are associated with lipopolysaccharide and capsule antigens, respectively, not flagella. Option D is incorrect as well because the correct association is with the H-antigen.
On the 8th day since the patient was inoculated with antitetanic serum because of dirty wound of his foot he has developed rising temperature up to 380% , pains in the joints, rash and itch. The blood tests revealed leukopenia and thrombocytopenia. Allergic reaction of what type has developed in this case?
- A. Anaphylactic
- B. Cytotoxic
- C. Delayed type of hypersensitivity
- D. Immunocomplex
Correct Answer: D
Rationale: The correct answer is D: Immunocomplex. In this case, the patient's symptoms of fever, joint pains, rash, and itch along with leukopenia and thrombocytopenia indicate a serum sickness reaction. This is a type III hypersensitivity reaction where antigen-antibody complexes deposit in tissues, leading to inflammation and tissue damage. The symptoms typically occur 1-2 weeks after exposure to the antigen. Anaphylactic reaction (choice A) is immediate and involves IgE antibodies. Cytotoxic reaction (choice B) involves destruction of cells by antibodies. Delayed hypersensitivity (choice C) usually takes 48-72 hours to develop and involves T-cells. Therefore, the correct answer is D as it aligns with the symptoms and timeline of a type III hypersensitivity reaction.