Cephalosporins, Vancomycin and Carbapenems MCQs

Treatment options for Clostridium difficile infection (CDI) typically include oral vancomycin or fidaxomicin. Fidaxomicin is a macrocyclic antibiotic (related to macrolides) that inhibits the sigma subunit of RNA polymerase , leading to protein synthesis impairment and cell death (bactericidal activity against C difficile). It is administered orally and has minimal systemic absorption, resulting in high fecal concentrations) also has a narrow spectrum of activity with a lesser effect on normal colonic flora than vancomycin. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 1105

A limiting feature of imipenem is its rapid hydrolysis by the enzyme dehydropeptidase I located on the brush border of renal tubular cells. An innovative solution to this problem is its combination with cilastatin, a reversible inhibitor of dehydropeptidase I, which has matched pharmacokinetics with imipenem (t½ of both is 1 hr) and protects it. Options B,C,D are not the correct reasons why Imipenem is given with Cilastatin.

Fever, productive cough, crackles, and an infiltrate on chest x-ray are consistent with community-acquired pneumonia (CAP). Gram negative rods and oxidase-positive rods suggest Pseudomonas aeruginosa is the most likely causative organism Cefepime and levofloxacin are the first-line treatment for patients with CAP when there is a strong suspicion of P. aeruginosa infection. Other treatment options for CAP with P. aeruginosa include piperacillin/tazobactam, meropenem, or imipenem plus a fluoroquinolone. An aminoglycoside may be added as well. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 838-39