Identification of Klebsiella pneumoniae K1 and K2 Capsular Types by PCR and Quellung Test

Background: Klebseilla pneumoniae causes urinary tract infections, nosocomial pneumonia and intra-abdominal infections. Capsular antigens are considered to be the ultimate virulence determinants. Among 77 capsular serotypes of K. pneumoniae, serotypes K1 and K2 are the most virulent ones in humans. Objectives: We designed a PCR method for detection of capsular serotypes K1 and K2 of K. pneumoniae using genes cps cluster wzc and orf10 which are required for biosynthesis of capsular polysaccharides in K1 and K2 types, respectively. Materials and Methods: We collected 89 K. pneumoniae clinical isolates from the patients of Labafinejad Hospital located in Tehran. Clinical isolates were mostly chosen from urine. We used PCR technique to detect isolates possessing K1 and K2 capsular polysaccharides based on the wzc and orf10 genes which are required for biosynthesis of capsular polysaccharide in K1 and K2 types, respectively. The results of PCR were compared with those obtained by capsular serotyping using Quellung test. Results: Of 89 isolates of K. pneumoniae tested by both techniques, 10 (11.2%) belonged to K1 and 13 (14.6%) belonged to K2 serotypes, respectively. Conclusions: We found that these serotypes are probably important in clinical specimens. PCR was a simple and inexpensive tool for identification of K. pneumoniae clinical isolates of K1 and K2 geno-serotypes.