Molecular Epidemiology and Risk Factors of Carbapenem-Resistant Klebsiella pneumoniae Infections in Eastern China

Background: The increasing prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) poses an immediate threat to treatment worldwide. This retrospective study assessed the molecular epidemiology and determined the risk factors for and outcomes of CRKP infections in a general teaching hospital in Shanghai, China. Methods: From January 2013 to July 2015, 100 consecutive unique CRKP isolates isolated from hospitalized patients were collected. Isolates were screened for antibiotic resistance genes by polymerase chain reaction (PCR) and molecular typing was performed by pulsed-field gel electrophoresis (PFGE). Patients infected with CRKP comprised the case group and were compared to the control group of patients infected with carbapenem-susceptible Klebsiella pneumoniae (CSKP). Therapeutic effects were compared in the CRKP infection group. Results: Among the 100 CRKP isolates, the percentages of multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug-resistant (PDR) were 50.0%, 50.0% and 0% respectively. All the CRKP isolates produced KPC-2 and could be divided into 18 PFGE clusters (A-O) and 70 subtypes. No dominant intra-hospital PFGE type was detected using a cutoff of 80% similarity. The ratio of CRKP infection to colonization was 51 to 49. Risk factors correlated with CRKP infection included pulmonary disease (p=0.038), ICU stay (p=0.002), invasive ventilation (p=0.009), blood transfusion (p=0.028), parenteral nutrition (p=0.004), sputum suction (p=0.006), medical history of previous hospitalization (p=0.022), exposure to antibiotics 90 days before infection (p=0.030), and antibiotic exposure during hospital stay including carbapenems (p=0.013), enzyme inhibitors (p=0.021), nitroimidazoles (p=0.029), and glycopeptides (p=0.000). Multivariable analysis showed that sputum suction [odds ratio (OR) 3.090, 95% confidence intervals (CIs) 1.004-9.518, p=0.049] was an independent risk factor for CRKP infections. Patients infected with CRKP with longer carbapenems treatment course (p=0.002) showed better outcome. Conclusion: This study showed the severity of CRKP infection in eastern China. Sputum suction was an independent risk factor for CRKP infection. Prolonged duration of treatment with carbapenems benefited the patients infected with CRKP.