Molecular epidemiology of carbapenem-resistant Klebsiella pneumoniae strains isolated between 2004-2007 in Ankara University Hospital, Turkey]

The prevalence of carbapenem-resistant gram-negative bacteria in the hospital setting is in an increasing trend worldwide. Since most of the carbapenem-resistant Enterobacteriaceae are resistant to all antimicrobial agents except polymyxins and tigecycline, the emergence of carbapenem resistance in Klebsiella pneumoniae strains requires careful monitoring. This study was conducted to analyse the epidemiological relatedness between the carbapenem-resistant isolates of K.pneumoniae collected from different wards (intensive-care, surgery, hematology, neurology, internal medicine, emergency services) of Ankara University Hospital. A total of 26 carbapenem-resistant K.pneumoniae isolates (13 blood, 6 urine, 2 bronchoalveolar lavage, I abscess, 1 tissue, 1 catheter tip, I drainage fluid, 1 tracheal lavage fluid) were identified and antibiotic susceptibility tests were performed with API 20E System or VITEK 2 Compact (Bio-Merieux, France) at the Central Laboratories of Ankara University Hospital between February 2004 and April 2007. MICs of imipenem and meropenem were also confirmed using E-test (AB Biodisk, Sweden). The clonal relationship between the isolates was studied by pulsed-field gel electrophoresis (PFGE). After digestion of total genomic DNA with restriction endonuclease Xbal, the 26 isolates generated 7 PFGE profiles. PFGE pattern B consisting of different antibiotic susceptibility profile was seen only in 2006. Carbapenem-sensitive strains isolated at the same time from the same wards which carbapenem-resistant isolates were recovered, generated different PFGE patterns. The predominant carbapenem-resistant isolates in our hospital were found clonally related. Interhospital transmission of carbapenem-resistant K.pneumoniae strains which have a particular epidemic potential, is likely to occur during patient transfer between wards. It is likely that intensive efforts, similar to those used to control vancomycin resistant enterococci, are needed to identify and control the spread of resistant Klebsiella species. Therefore, active surveillance and strict infection control measures for this multidrug-resistant microorganism should be implemented at local and national basis.