Emergence and clonal spread of KPC-2-producing clinical Klebsiella aerogenes isolates in a hospital from northwest Argentina

Abstract

Introduction. Klebsiella aerogenes is a nosocomial pathogen associated with drug resistance and healthcare-associated infections. Gap Statement. K. aerogenes is associated with hospital-acquired infections with the ability to acquire mechanisms of resistance to reserve antimicrobials; its clinical behaviour has been poorly documented. Objective. We proposed to investigate an outbreak of carbapenem-resistant K. aerogenes in a hospital that persisted for 4 months. Methods. The primary aim was to evaluate the molecular characteristics and the clonal relationships among the isolates. We characterized isolates by polymerase chain reaction (PCR) and pulsed-field gel electrophoresis (PFGE). The information was integrated with clinical and epidemiological data. Results. Fourteen strains were disseminated in an intensive care unit and different wards at the hospital. The overall mortality was 42.8 %, and mortality attributed to infection was 21.4 %; strains showed high rates of resistance to most of the antimicrobials tested and carried bla KPC-2, bla SHV-2 and bla CTXM-15 genes. PFGE analysis indicated 2 PFGE groups; 12/14 isolates were associated with subgroup A and were likely to be primarily responsible for the first isolation and subsequent dissemination. The outbreak characteristics data showed prolonged hospitalization and previous use of antibiotics as potential risk factors. Conclusion. We consider that it is essential to perform phenotypic and genotypic identification of early genetic resistance mechanisms in K. aerogenes isolates, not only from infection sites but also from colonization, to prevent the spread of these multidrug-resistant (MDR) isolates.