A patient is on ampicillin for a urinary tract infection. The organism is found to produce extended-spectrum beta-lactamase (ESBL). Which combination would be the most appropriate alternative?

• A Ampicillin + clavulanic acid (co-amoxiclav)
• B Amoxicillin-clavulanate (for ESBL it requires carbapenem)
• C Ceftriaxone + sulbactam
• D Ertapenem (a carbapenem not susceptible to ESBL hydrolysis) ✓

Explanation

ESBL-producing organisms hydrolyze most penicillins, cephalosporins (including ceftriaxone), and aztreonam. Beta-lactamase inhibitors like clavulanate incompletely inhibit ESBLs when clinical inoculum is high (inoculum effect). Carbapenems (imipenem, meropenem, ertapenem) are stable against ESBL hydrolysis and remain first-line treatment. Ertapenem (once-daily IM/IV) is appropriate for uncomplicated ESBL UTI. Carbapenemase-producing organisms (KPC, NDM) require further escalation.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.