The Gram-negative opportunistic pat

The Gram-negative opportunistic pathogen Klebsiella pneumoniae is a significant cause of community-acquired and healthcare-associated infections for which multidrug resistance is a concern worldwide. A major virulence determinant of K. pneumoniae is a polysaccharide capsule (CPS) which forms a barrier around the bacterial cell wall, providing protection from environmental pressures and immune responses of eukaryotic organisms. More than 70 chemical capsule structures of serologically typeable K. pneumoniae strains are known. However, there are little data on the CPS structure and cps gene cluster organization of clinical multidrug resistant K. pneumoniae strains. Our investigation of multidrug resistant carbapenemase OXA-48-producing K. pneumoniae strain KPB536 identified a capsular type that was structurally similar to K. pneumoniae K10 but different from any K. pneumoniae CPS reported so far. The content and organization of the cps gene cluster in K. pneumoniae KPB536 also was determined. The catalytic functions of glycosyltransferases coded by the cps_KPB536 gene cluster were assigned by comparison with those responsible for the synthesis of glycoside linkages in the CPSs of K. pneumoniae types K10 and K61.