Which of the following statements about vancomycin is accurate?

Correct Answer: C

Rationale: In the context of a Drugs and immune system exam, the accurate statement about vancomycin is option C) It is not susceptible to penicillinase. This is because vancomycin is a glycopeptide antibiotic that works by inhibiting cell wall synthesis in bacteria, making it effective against a wide range of gram-positive bacteria including those resistant to beta-lactam antibiotics like penicillin. Vancomycin achieves its bactericidal effect by binding to the D-Ala-D-Ala terminus of cell wall precursors, thereby preventing cross-linking of peptidoglycan chains. Option A) It is bacteriostatic is incorrect because vancomycin is actually bactericidal, meaning it kills bacteria rather than just inhibiting their growth. Option B) It binds to PBPs is incorrect as vancomycin acts by binding to the D-Ala-D-Ala terminus of cell wall precursors, not to penicillin-binding proteins (PBPs) which are the target of beta-lactam antibiotics. Option D) It has the advantage of oral bioavailability is incorrect because vancomycin has very poor oral bioavailability and is typically administered intravenously to achieve therapeutic levels. Understanding the mechanism of action and characteristics of vancomycin is crucial in clinical practice to ensure appropriate use of this antibiotic and to prevent the development of antibiotic resistance. This knowledge is essential for healthcare professionals involved in prescribing, administering, and monitoring patients receiving vancomycin therapy.

Correct Answer: B

Rationale: In this scenario, the correct answer is B) Gentamicin. Gentamicin is an aminoglycoside antibiotic that acts synergistically with penicillin G against enterococci. This combination is effective because aminoglycosides enhance the penetration of cell wall-active antibiotics like penicillin G, thereby improving their efficacy against certain bacteria like enterococci. Now, let's discuss why the other options are incorrect: A) Amikacin is another aminoglycoside antibiotic, but it is not the most effective agent in this context. Gentamicin has been shown to have better synergy with penicillin G against enterococci. C) Netilmicin, like amikacin, is an aminoglycoside antibiotic that is not as effective as gentamicin when used in conjunction with penicillin G for treating enterococci infections. D) Streptomycin is another aminoglycoside antibiotic, but it is not the most suitable choice for treating enterococci infections when compared to gentamicin. From an educational perspective, understanding the concept of antibiotic synergy is crucial in clinical practice. It is important for healthcare professionals to know which antibiotics work best together to effectively target specific pathogens. This knowledge helps in making informed decisions regarding antibiotic therapy, ultimately leading to better patient outcomes and reduced antibiotic resistance.

Correct Answer: B

Rationale: In this scenario, the correct answer is B) Ceftriaxone. The rationale behind this choice is that Ceftriaxone is the recommended treatment for gonorrhea in pregnant patients, particularly in cases where the patient has a history of anaphylaxis to amoxicillin. Ceftriaxone is effective against gonorrhea and is safe to use during pregnancy. It is also given as a single dose, which aligns with the need for compliance in this case. Option A) Cefixime is no longer recommended as a first-line treatment for gonorrhea due to increasing resistance. Option C) Ciprofloxacin is not recommended for treating gonorrhea due to high rates of resistance. Option D) Spectinomycin is an alternative treatment for gonorrhea but is not the first-line choice, especially in pregnant patients. In an educational context, this question highlights the importance of selecting the most appropriate treatment for a pregnant patient with a history of drug allergies. It emphasizes the need to consider factors like efficacy, safety during pregnancy, and patient compliance when making treatment decisions in clinical practice.

Correct Answer: B

Rationale: The correct answer is B) Cefazolin, which does not require supplementation of dosage following hemodialysis. Cefazolin is a first-generation cephalosporin antibiotic that does not require dosage adjustment after hemodialysis because it is primarily eliminated by the liver. This is due to its low molecular weight and minimal protein binding, which allows it to be efficiently cleared by the liver rather than the kidneys. A) Ampicillin is a penicillin antibiotic that does require dosage adjustment after hemodialysis because it is primarily excreted by the kidneys. Hemodialysis can remove a significant amount of ampicillin from the bloodstream, necessitating supplementation. C) Ganciclovir is an antiviral medication that is eliminated by the kidneys, so it requires dosage adjustment after hemodialysis to maintain therapeutic levels in the body. D) Tobramycin is an aminoglycoside antibiotic that is primarily excreted by the kidneys and is removed during hemodialysis. Therefore, it requires dosage supplementation post-hemodialysis to ensure effective treatment. Understanding the pharmacokinetics of antimicrobial drugs is crucial for healthcare professionals, especially when managing patients undergoing hemodialysis. Knowledge of which drugs require dosage adjustments post-hemodialysis can prevent under or overdosing, ensuring optimal therapeutic outcomes and reducing the risk of adverse effects.

Correct Answer: B

Rationale: The correct answer is B) Ceftriaxone. Ceftriaxone is a third-generation cephalosporin that is effective against a broad spectrum of bacteria, including Haemophilus influenzae, Moraxella catarrhalis, and Neisseria gonorrhoeae. These bacteria are known to produce beta-lactamase, an enzyme that inactivates penicillin G. Ceftriaxone is less susceptible to beta-lactamase degradation compared to penicillin G, making it an effective choice against these organisms. Option A) Ampicillin is a penicillin-based antibiotic and is susceptible to degradation by beta-lactamase, thus not effective against strains producing this enzyme. Option C) Clindamycin is not a preferred choice for treating infections caused by these specific organisms and may not provide adequate coverage. Option D) Gentamicin is an aminoglycoside antibiotic that is not typically used as a first-line treatment for infections caused by these bacteria and may not be effective against beta-lactamase-producing strains. Educationally, understanding the mechanisms of antibiotic resistance, such as beta-lactamase production, is crucial for selecting appropriate antibiotics for treatment. Knowing the spectrum of activity and resistance patterns of different antibiotics helps healthcare professionals make informed decisions to effectively treat bacterial infections and prevent the development of further resistance.