Pulsed-field gel electrophoresis characterization of Bordetella pertussis clinical isolates circulating in Turkey in 2001–2009

Our purpose was to evaluate the natural epidemiological history of circulating Bordetella pertussis clinical isolates in Turkey, comparing isolates by means of pulsed-field gel electrophoresis (PFGE) profiles according to years, geographic regions, vaccination status, and demographic characteristics. We analyzed genotypically a collection of 92 clinical isolates recovered during the period 2001–2009 at the National Pertussis Reference Laboratory by PFGE. A total of 61 genotypes were identified among the 92 isolates. Fifteen of 61 genotypes were a cluster including 46 isolates, and the remaining 46 genotypes were unique. The clustering rate was 50% (46/92). The size of the cluster varied from 2 to 14 clinical isolates. There was no association between clustering rates and age, gender, or quarterly season. The clustering rate was significantly higher in 2006. When the isolates were grouped according to similarity coefficient higher than 85%, 89 (96.7%) of the 92 isolates were clonally related. There was one major group including 65.2% of the isolates mainly observed. This is the first study on the molecular characterization of B. pertussis isolates in Turkey. We consider that this study lays a good foundation for further monitoring of the circulating B. pertussis clinical isolates in Turkey.