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

Summary Background Reports of KPC-producing Klebsiella pneumoniae (KPC-Kp) in Australia were previously uncommon with cases sporadically imported by travellers from higher prevalence countries. Aim Our institution reported the first outbreak of KPC-Kp in Australia. The aim of this study was to identify risk factors for KPC-Kp colonisation and infection using a matched case control study. Methods The study included all hospitalised patients with KPC-Kp colonisation or infection from January 2012 to September 2015. Findings Thirty four cases of KPC-producing Enterobacteriaceae (including 31 KPC-Kp cases) were matched to 136 controls. Variables associated with KPC-Kp acquisition included: length of hospital stay > 28 days in the past 12 months, prior vancomycin-resistant Enterococcus (VRE) colonisation, central venous catheter (CVC), gastrointestinal disease, and invasive procedures. Exposures to broad-spectrum antibiotics were also found to be significant risk factors. In the multivariate analysis, three factors independently associated with KPC–Kp acquisition were length of hospital stay > 28 days in the past 12 months (OR 23.6, 95% CI 4.9 – 113.3), presence of a CVC (OR 15.4, 95% CI 2.7 – 86.9), and prior VRE colonisation (OR 6.0, 95% CI 1.6 – 23.2). Very few patients had a history of overseas travel. Conclusion Our study demonstrates that patients with prolonged hospital exposure are more likely to acquire KPC-Kp in the setting of a local outbreak, and it 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.