Infections caused by Klebsiella pneumoniae (Kp) carbapenemase (KPC)-producing strains of Kp have become a significant threat in recent years. To assess their outcomes and identify risk factors for 14 day mortality, we conducted a 4 year (2010–13) retrospective cohort study in five large Italian teaching hospitals.

The cohort included 661 adults with bloodstream infections (BSIs; n = 447) or non-bacteraemic infections (lower respiratory tract, intra-abdominal structure, urinary tract or other sites) caused by a KPC-Kp isolate. All had received ≥48 h of therapy (empirical and/or non-empirical) with at least one drug to which the isolate was susceptible.

Most deaths occurred within 2 weeks of infection onset (14 day mortality: 225/661, 34.1%). Logistic regression analysis identified BSI (OR, 2.09; 95% CI, 1.34–3.29), presentation with septic shock (OR, 2.45; 95% CI, 1.47–4.08), inadequate empirical antimicrobial therapy (OR, 1.48; 95% CI, 1.01–2.18), chronic renal failure (OR, 2.27; 95% CI, 1.44–3.58), high APACHE III score (OR, 1.05; 95% CI, 1.04–1.07) and colistin-resistant isolates (OR, 2.18; 95% CI, 1.37–3.46) as independent predictors of 14 day mortality. Combination therapy with at least two drugs displaying in vitro activity against the isolate was associated with lower mortality (OR, 0.52; 95% CI, 0.35–0.77), in particular in patients with BSIs, lung infections or high APACHE III scores and/or septic shock at infection onset. Combinations that included meropenem were associated with significantly higher survival rates when the KPC-Kp isolate had a meropenem MIC of ≤8 mg/L.

KPC-Kp infections are associated with high mortality. Treatment with two or more drugs displaying activity against the isolate improves survival, mainly in patients who are critically ill.