Factors influencing survival in patients with multi-drug-resistant Acinetobacter bacteraemia

The incidence of multi-drug-resistant (MDR) Acinetobacter strains is increasing and therapeutic options are limited. However, controversy exists regarding the mortality attributable to antimicrobial resistance. The aim of this study was to analyse the clinical features and outcomes of patients with MDR Acinetobacter calcoaceticus-Acinetobacter baumannii complex (Acb complex) bacteraemia and determine the factors influencing survival by using 14-day mortality as the main outcome measure.

An observational study was conducted at a tertiary care hospital in Turkey from February 2007 to March 2008. Only one bacteraemic episode from one patient was included in the study.

A total of 100 clinically significant Acb complex bacteraemic episodes were detected. The overall mortality was 63% in 14 days. According to univariate analysis, diabetes mellitus, haematological malignancy, unknown source of bacteraemia, septic shock, resistance to carbapenems, and inappropriate empirical therapy were associated with mortality amongst patients with Acb complex bacteraemia. Multivariate analysis showed that diabetes mellitus (RR, 1.68; 95% CI, 1.22-1.76), carbapenem resistance (RR, 1.63; 95% CI, 1.19-1.89), and septic shock (RR, 1.65; 95% CI, 1.23-1.85) were independent risk factors for 14-day mortality.

Although severe underlying diseases play an important role in the clinical outcome of patients with Acb complex bacteraemia, carbapenem resistance and inappropriate therapy are of great concern. Special attention should be paid to infection control practices in the hospitals where MDR Acinetobacter infections are endemic, and well-controlled prospective clinical trials are needed to determine the optimal antimicrobial therapy in critically ill patients suspected of having MDR Acinetobacter bacteraemia.