Erythromycin is the drug of choice in

Correct Answer: A

Rationale: In the context of this question, the correct answer is A) Pertussis. Erythromycin is the drug of choice for treating pertussis, also known as whooping cough, due to its effectiveness against the causative bacterium, Bordetella pertussis. Erythromycin works by inhibiting bacterial protein synthesis, thus helping to eradicate the infection. Option B) Gonococcal urethritis is typically treated with antibiotics such as ceftriaxone or azithromycin, as gonorrhea is caused by Neisseria gonorrhoeae which has developed resistance to erythromycin. Option C) Prophylaxis of bacterial endocarditis usually involves antibiotics like amoxicillin or clindamycin, not erythromycin. Option D) Chlamydial infections are commonly treated with antibiotics such as azithromycin or doxycycline, as Chlamydia trachomatis is not effectively treated by erythromycin. Educationally, understanding the appropriate use of antibiotics in specific infections is crucial for healthcare providers to effectively treat patients and prevent the development of antibiotic resistance. It is important for students to grasp the rationale behind drug choices to provide safe and evidence-based care to patients.

Correct Answer: B

Rationale: In the context of drugs for the immune system, understanding the activity of antibiotics like Streptomycin at different pH levels is crucial for their effectiveness. The correct answer, B) pH 8.5 than pH 5.5 of urine, is based on the pharmacokinetics of Streptomycin. Streptomycin is more active at alkaline pH levels like 8.5 because it is a weak base and its solubility and activity increase in alkaline environments. This is important to know for dosing and treatment efficacy. Option A) pH 5.5 than pH 8.5 of urine is incorrect because acidic pH levels would actually decrease the activity of Streptomycin. In acidic conditions, Streptomycin may become less soluble and therefore less effective. Option C) Equally active at all pH of urine is incorrect because, as mentioned earlier, Streptomycin's activity is pH-dependent due to its chemical properties as a weak base. It is not equally active across all pH levels. Option D) All of the above is incorrect because Streptomycin does not exhibit consistent activity across different pH levels. Understanding this concept is important in clinical practice when prescribing antibiotics and ensuring their optimal effectiveness in treating infections.

Correct Answer: A

Rationale: Benzylpenicillin, also known as penicillin G, is not used orally because it is destroyed by the acidic environment of the stomach. This leads to incomplete absorption of the drug when taken orally. The correct answer A is the most accurate because oral administration of benzylpenicillin would render it ineffective due to its susceptibility to acid degradation. Option B is incorrect because even if benzylpenicillin were well absorbed from the intestine, the issue lies with its destruction in the stomach, making absorption from the intestine irrelevant for oral administration. Option C is also incorrect as severe diarrhea is not a known side effect of benzylpenicillin. The primary reason for not using benzylpenicillin orally is its susceptibility to being destroyed by stomach acid. In an educational context, understanding the pharmacokinetics of drugs is crucial for healthcare professionals. Knowing why certain drugs cannot be administered via specific routes helps in ensuring their efficacy and patient safety. This question highlights the importance of drug administration routes and their implications on drug effectiveness.

Correct Answer: B

Rationale: Cephalosporins are a class of beta-lactam antibiotics, containing a beta-lactam ring in their chemical structure. Option B, "Are less vulnerable to beta-lactamase enzyme," is correct because cephalosporins are less susceptible to degradation by beta-lactamase enzymes compared to penicillins. This is due to the presence of a dihydrothiazine ring in cephalosporins, which provides some protection against beta-lactamase enzymes. Option A, "Are more vulnerable to beta-lactamase enzyme," is incorrect because, as mentioned, cephalosporins are actually less vulnerable to beta-lactamase enzymes compared to penicillins. Option C, "Do not possess beta-lactam ring," is incorrect because cephalosporins do contain a beta-lactam ring in their structure, which is essential for their antibacterial activity. Option D, "Have multiple beta-lactam rings," is incorrect because cephalosporins typically have one beta-lactam ring in their chemical structure, not multiple rings. In an educational context, understanding the susceptibility of antibiotics to beta-lactamase enzymes is crucial for selecting appropriate treatment options for bacterial infections. Knowing that cephalosporins are less vulnerable to beta-lactamase enzymes compared to penicillins can help healthcare professionals make informed decisions when prescribing antibiotics to patients.

Correct Answer: A

Rationale: The correct answer is A) Griseofulvin. Griseofulvin is the drug of choice for treating ringworm infections because it specifically targets fungal infections like those caused by dermatophytes, which are responsible for ringworm. Griseofulvin works by inhibiting fungal cell division, thus stopping the growth and spread of the fungus. Option B) Amphotericin B is an antifungal medication, but it is not typically used for ringworm infections. It is more commonly used for severe systemic fungal infections. Option C) Nystatin is an antifungal medication used to treat yeast infections, like thrush, but it is not effective against dermatophytes that cause ringworm. Option D) Neomycin is an antibiotic that is used to treat bacterial infections, not fungal infections like ringworm. In an educational context, understanding the appropriate drug for specific infections is crucial for healthcare professionals to provide effective treatment. Knowing the mechanism of action and spectrum of activity of each drug helps in making informed decisions when prescribing medications. It is important to differentiate between antifungal and antibacterial medications to ensure the proper treatment of infections.