Nokea
Isoniazid is a primary antitubercular agent that:
- A. Requires pyridoxine (Vit B6) supplementation
- B. Penetrates the BBB and enters the brain useful in TB meningitis
- C. Causes ocular complications that are reversible if the drug is discontinued
- D. May be ototoxic and nephrotoxic
Correct Answer: A
Rationale: Step-by-step rationale for choice A being correct:
1. Isoniazid can lead to pyridoxine deficiency.
2. Pyridoxine supplementation helps prevent neurotoxicity.
3. Thus, isoniazid therapy requires pyridoxine supplementation.
Summary of why other choices are incorrect:
B: Isoniazid does not effectively penetrate the BBB.
C: Ocular complications of isoniazid are generally irreversible.
D: Ototoxicity and nephrotoxicity are not common side effects of isoniazid.
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Which of the following cephalosporins has in vitro activity against anaerobic gram negative bacteria such as Bacteroides fragilis?
- A. Cefdinir
- B. Cefuroxime
- C. Cefazolin
- D. Cefepime
Correct Answer: B
Rationale: The correct answer is B: Cefuroxime. Cefuroxime is a second-generation cephalosporin that has demonstrated in vitro activity against anaerobic gram-negative bacteria like Bacteroides fragilis. This is due to its broader spectrum of activity compared to other choices.
A: Cefdinir is a third-generation cephalosporin with limited activity against anaerobic gram-negative bacteria.
C: Cefazolin is a first-generation cephalosporin primarily effective against aerobic gram-positive bacteria.
D: Cefepime is a fourth-generation cephalosporin with limited activity against anaerobic gram-negative bacteria.
Which statement concerning the testes is true?
- A. The lymphatic vessels of the testes drain into the abdominal lymph nodes.
- B. The vas deferens is located along the inferior portion of each testis.
- C. The right testis is lower than the left because the right spermatic cord is longer.
- D. The cremaster muscle contracts in response to cold and draws the testicles closer to the body.
Correct Answer: D
Rationale: The correct answer is D: The cremaster muscle contracts in response to cold and draws the testicles closer to the body. This is true because the cremaster muscle is responsible for regulating the position of the testicles in response to temperature changes to maintain optimal conditions for sperm production. The other choices are incorrect because: A: The lymphatic vessels of the testes drain into the para-aortic lymph nodes, not the abdominal lymph nodes. B: The vas deferens is a duct that carries sperm from the testes to the urethra, not located along the inferior portion of each testis. C: The difference in height between the testes is due to differences in the descent of the testes during fetal development, not the length of the spermatic cord.
The ________ is the endometrial layer that remains essentially unchanged during the menstrual
- A. myometrium
- B. functional layer
- C. corpus albicans
- D. basal layer
Correct Answer: D
Rationale: The correct answer is D: basal layer. The basal layer is the endometrial layer that remains essentially unchanged during the menstrual cycle. This layer serves as the foundation for the regrowth of the functional layer after menstruation. The myometrium (A) is the smooth muscle layer of the uterus, not the endometrial layer. The functional layer (B) is shed during menstruation and regenerates each cycle. The corpus albicans (C) is a remnant of the corpus luteum in the ovary, not related to the endometrium. Therefore, the basal layer is the correct answer as it is the only layer that remains unchanged during the menstrual cycle.
The drug of choice for monilial diarrhea is:
- A. Amphothericin B
- B. Nystatin
- C. Ketoconazole
- D. Itraconazole
Correct Answer: B
Rationale: Step-by-step rationale for why Nystatin is the correct choice for monilial diarrhea:
1. Nystatin is an antifungal medication specifically effective against Candida species causing monilial infections.
2. It works by binding to ergosterol in fungal cell membranes, disrupting membrane integrity and causing cell death.
3. Nystatin is not absorbed systemically, making it suitable for gastrointestinal infections.
4. Amphothericin B is reserved for severe systemic fungal infections due to its significant toxicity. Ketoconazole and Itraconazole are not typically used for gastrointestinal Candida infections, as they are more commonly used for systemic fungal infections.
Which is incorrect regarding the investigation of UTI?
- A. The sensitivity of dipstick for nitrites is 96%.
- B. A positive dipstick for leucocyte esterase is 96% specific for >10 wbc/mm .
- C. A bacterial culture with > 10 has 95% probability of representing infection.
- D. Use of blood cultures in does not change management when urine culture is taken.
Correct Answer: B
Rationale: The correct answer is B because a positive dipstick for leucocyte esterase is not 96% specific for >10 wbc/mm³. Leucocyte esterase can indicate the presence of white blood cells, but it does not quantitatively correlate with a specific wbc count. Therefore, it cannot be used to accurately determine the exact wbc count in the urine sample.
A: The sensitivity of dipstick for nitrites being 96% means it is good at detecting nitrites, which are a sign of bacterial infection in the urine.
C: A bacterial culture with >10^5 colony-forming units has a high probability of representing infection, typically around 95%.
D: Blood cultures are not routinely used for diagnosing UTIs; urine culture is the primary method. Blood cultures are more often used for systemic infections.