Risk factors for KPC-producing Enterobacteriaceae acquisition and infection in a healthcare setting with possible local transmission: a case-control study

Abstract

Background: Reports of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-Kp) in Australia were previously uncommon, with cases imported sporadically by travellers from higher prevalence countries.

Aim: The study institution reported the first outbreak of KPC-Kp in Australia. The aim of this study was to identify risk factors for KPC-Kp colonization and infection using a matched case-control study.

Methods: The study included all hospitalized patients with KPC-Kp colonization or infection from January 2012 to September 2015.

Findings: Thirty-four cases of KPC-producing Enterobacteriaceae (including 31 KPC-Kp cases) were matched with 136 controls. Variables associated with KPC-Kp acquisition included: length of hospital stay >28 days in the past 12 months, prior vancomycin-resistant enterococci (VRE) colonization, central venous catheter (CVC), gastrointestinal disease and invasive procedures. Exposure to broad-spectrum antibiotics was also found to be a significant risk factor. In the multi-variate analysis, three factors independently associated with KPC-Kp acquisition were length of hospital stay >28 days in the past 12 months [odds ratio (OR) 23.6, 95% confidence interval (CI) 4.9-113.3], presence of a CVC (OR 15.4, 95% CI 2.7-86.9), and prior VRE colonization (OR 6.0, 95% CI 1.6-23.2). Very few patients had a history of overseas travel.

Conclusion: This study demonstrates that patients with prolonged hospital exposure are more likely to acquire KPC-Kp in the setting of a local outbreak, and suggests that risk factors for KPC-Kp acquisition may be shared with those for VRE colonization. Local screening strategies targeting overseas travellers would likely miss many cases. The results of this study will help to inform screening policies for carbapenemase-producing Enterobacteriaceae.

Keywords: Antimicrobial resistance; Carbapenemase-producing Enterobacteriaceae; Case–control study; Klebsiella pneumoniae carbapenemase; Outbreak.