Risk factors of carbapenem-resistant Klebsiella pneumoniae infections: a matched case–control study

Background Carbapenems are frequently used to treat infections due to extended-spectrum β-lactamase-producing Klebsiella pneumoniae. Thus, the emergence of infections due to carbapenem-resistant K. pneumoniae (CRKp) is a major public health concern. Objectives To identify risk factors associated with the development of CRKp infections. Methods We conducted a matched case–control study in two hospitals (Henry Dunant Hospital, Athens, Greece and University Hospital of Heraklion, Crete, Greece). The controls were selected among patients with carbapenem-susceptible K. pneumoniae (CSKp) and were matched with CRKp cases for site of infection. Results One hundred and six patients were included in our study (53 cases and 53 controls). Mortality was 30.1% and 33.9% for patients with CRKp and CSKp infections, respectively (P = 0.83). Bivariable analysis showed that exposure to anti-pseudomonas penicillins (P = 0.004), carbapenems (P = 0.01), quinolones (P < 0.001) and glycopeptides (P < 0.001), as well as admission to the intensive care unit (P = 0.002), tracheostomy (P = 0.02), chronic obstructive pulmonary disease (P = 0.04), surgery with use of foreign body (P = 0.04) and mechanical ventilation (P = 0.02) were associated with CRKp infection. The multivariable analysis showed that exposure to fluoroquinolones [odds ratio (OR) 4.54, 95% confidence intervals (CIs) 1.78–11.54, P = 0.001] and exposure to antipseudomonal penicillins (OR 2.57, 95% CI 1.00–6.71, P = 0.04) were independent risk factors for CRKp infections. Conclusions Our data suggest that prior exposure to fluoroquinolones and antipseudomonal penicillins are independent risk factors for the development of CRKp infections.