An Outbreak of Infection due to β‐LactamaseKlebsiella pneumoniaeCarbapenemase 2–ProducingK. pneumoniaein a Greek University Hospital: Molecular Characterization, Epidemiology, and Outcomes

Abstract

Background. We describe the emergence and spread of Klebsiella pneumoniae carbapenemase 2 (KPC-2)–producing K. pneumoniae at a Greek University hospital. Methods. Isolates with a carbapenem minimum inhibitory concentration >1 µg/mL and a negative EDTA-imipenem disk synergy test result were submitted to boronic acid disk test and to polymerase chain reaction (PCR) for KPC gene and sequencing. Records from patients who had KPC-2–producing K. pneumoniae isolated were retrospectively reviewed. Clinical isolates were submitted to molecular typing using pulsed-field gel electrophoresis, and the β-lactamase content was studied using isoelectric focusing and PCR. Results. From January 2007 through December 2008, 50 patients (34 in the intensive care unit [ICU]) were colonized (n=32) or infected (n=18) by KPC-2–producing K. pneumoniae. Increasing prevalence of KPC-2–producing K. pneumoniae coincided with decreasing prevalence of metallo-β lactamase–producing isolates in our ICU. Multidrug resistance characterized the studied isolates, with colistin, gentamicin, and fosfomycin being the most active agents. Besides KPC-2, clinical isolates encoded TEM-1-like, SHV-11, SHV-12, CTX-M–15, and LEN-19 enzymes. Four different clonal types were detected; the predominant one comprised 41 single patient isolates (82%). Sporadic multiclonal cases of KPC-2–producing K. pneumoniae infection were identified from September 2007 through May 2008. The outbreak strain was introduced in February 2008 and disseminated rapidly by cross-transmission; 38 patients (76%) were identified after August 2008. Fourteen cases of bacteremia, 2 surgical site infections, 2 lower respiratory tract infections (1 bacteremic), and 1 urinary tract infection were identified. Most patients received a colistin-containing combination treatment. Crude mortality was 58.8% among ICU patients and 37.5% among non-ICU patients, but attributable mortality was 22.2% and 33.3%, respectively. Conclusions. The emergence of KPC-2–producing K. pneumoniae in Greek hospitals creates an important challenge for clinicians and hospital epidemiologists, because it is added to the already high burden of antimicrobial resistance.