Meropenem versus Piperacillin-Tazobactam for Definitive Treatment of Bloodstream Infections (MERINO)

Piperacillin-tazobactam (pip-tazo) was widely used as a carbapenem-sparing alternative for ESBL-producing Enterobacteriaceae bloodstream infections. MERINO definitively tested this practice.

Multicenter RCT (26 hospitals, 9 countries, n=391) comparing meropenem vs. piperacillin-tazobactam for definitive treatment of ESBL/AmpC-producing Enterobacteriaceae bloodstream infections.

30-day mortality was significantly higher with pip-tazo (12.3% vs 3.7%, p=0.90 for non-inferiority — pip-tazo FAILED non-inferiority). Pip-tazo was inferior to meropenem.

Piperacillin-tazobactam should NOT be used as definitive therapy for ESBL-producing Enterobacteriaceae bloodstream infections — use a carbapenem. This changed practice worldwide. Pip-tazo is acceptable for empiric therapy while awaiting sensitivities.

Excluded patients with urinary source (lower mortality). Used pip-tazo with extended infusion. Results may not apply to urinary tract infections.