A patient with enterococcal endocarditis receives intravenous penicillin G plus gentamicin for four weeks. The bactericidal outcome achieved by this combination, which neither drug produces reliably alone against Enterococcus, is best described as:

• A Synergistic killing through enhanced aminoglycoside uptake after cell wall disruption by the beta-lactam ✓
• B Additive inhibition of folate synthesis
• C Prevention of resistance by sequential blockade of ribosomal assembly
• D Post-antibiotic effect summation allowing once-daily dosing of both drugs

Explanation

Enterococci are tolerant to beta-lactams alone (bacteriostatic) and aminoglycosides alone fail because these organisms are facultative anaerobes with limited drug uptake. Penicillin damages the cell wall, permitting greater gentamicin penetration and concentration-dependent intracellular killing, producing true synergy. This is why high-level aminoglycoside resistance abolishes the benefit of adding gentamicin to the regimen.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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