Extended-spectrum beta-lactamase (ESBL) producing Klebsiella pneumoniae is isolated from a patient with ICU-acquired pneumonia. ESBLs are predominantly encoded on transferable plasmids. Which antibiotic class is currently the drug of choice for systemic infections caused by ESBL-producing Enterobacterales?
- A 3rd-generation cephalosporins (ceftriaxone)
- B Aminoglycosides (gentamicin)
- C Carbapenems (meropenem or imipenem) ✓
- D Beta-lactam/beta-lactamase inhibitor combinations (piperacillin-tazobactam)
Explanation
Carbapenems (meropenem, imipenem-cilastatin, ertapenem) are the drugs of choice for serious systemic infections caused by ESBL-producing organisms, as ESBLs (TEM, SHV, CTX-M types) hydrolyse all penicillins, cephalosporins, and aztreonam but not carbapenems. Cephalosporins are typically resistant despite appearing susceptible on initial susceptibility testing (inoculum effect). Piperacillin-tazobactam was historically used for non-severe infections but clinical failure has been documented at high MICs; most guidelines now recommend carbapenems for bacteraemia. Aminoglycosides may have co-resistance and are not first-line monotherapy for systemic infections.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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