What may be lurking in the hospital undergrowth? Inapparent cross-transmission of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae

Abstract

Background: Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae pose an increasing challenge in hospitals.

Aim: To describe the benefits of using molecular techniques to investigate the spread of ESBL-producing Klebsiella pneumoniae (ESBL-KP) within a tertiary referral centre.

Methods: Following the identification of a cluster of five ESBL-KP on one ward, a hospital-wide retrospective epidemiological investigation was undertaken into the incidence and spread of these organisms. Variable number tandem repeat (VNTR) profiles were used to assign patients to possible clusters. Patient outcome and length of hospital stay were reviewed. Locations of patients assigned to each cluster were investigated as possible sources of spread. Antimicrobial prescribing practices and hand hygiene compliance on affected wards were also reviewed.

Findings: Twenty-four ESBL-KP isolates were characterized by VNTR. The mean length of stay was 102.5 days for patients with ESBL-KP, which was significantly longer compared with the mean length of stay for all patients (10.1 days, P < 0.01). Nineteen patients were assigned to clusters with shared VNTR profiles. Review of patient transfer histories identified two instances where cross-transmission may have occurred. In both cases, compliance with good hand hygiene practice and antimicrobial prescribing was suboptimal.

Conclusion: Molecular typing provided a valuable insight into the clones of ESBL-KP circulating within the study institution. Increased surveillance to identify colonization among patients and routine typing of isolates should be considered, but the resource implications for patient isolation are considerable.

Keywords: ESBLs; Klebsiella pneumoniae; Outbreaks; Surveillance; VNTR.