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 beta-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.