Klebsiella pneumoniae is mostly responsible for nosocomial infections in immunocompromised patients, but can also cause severe community-acquired infections. The clinical scenario has worsened in recent years, with the global emergence and dissemination of K. pneumoniae strains resistant to carbapenems (CR-Kp). The major carbapenem resistance mechanism among CR-Kp is the production of carbapenemase, i.e. KPC. The most successful and widespread disseminated clonal group (CG) of KPC-producing K. pneumoniae (KPC-Kp) is CG258, which can be further differentiated in two clades characterized by the production of distinct capsular polysaccharides. Infections caused by KPC-Kp strains are challenging in healthcare settings, where they spread rapidly and are associated with significant morbidity and mortality [1].
Genotyping of the cps207-2 gene cluster with the wzc-based method showed that it is a new K-type, while the wzi-based method associated it to the already known K41 K-type.
Therefore, the primary structure of the capsular polysaccharide produced by K. pneumoniae KK207-2 [2], a member of the clade I of CG258, was determined by using GLC-MS of appropriate carbohydrate derivatives, ESI-MS of both partial hydrolysis and Smith degradation derived oligosaccharides, and NMR spectroscopy of oligosaccharides, lithium degraded CPS, and the native and de-O-acetylated CPS. The results showed that the repeating unit of KK207-2 capsular polysaccharide (Fig. 1a) is a novel one among the Klebsiella K-types. Moreover, each glycosyltransferase in the sequenced cps207-2 gene cluster was assigned to the corresponding catalyzed reaction (Fig. 1b, 1c).
Figure 1: (a) Structure of the capsular polysaccharide repeating unit of Klebsiella pneumoniae KK207-2. (b) Glycosyltransferases of the Klebsiella pneumoniae KK207-2 cps gene cluster are listed above the respective glycosidic linkage. The polymerization site is marked by an arrow. (c) Identification of genes coded in the central region of the cps207-2 cluster.
- Lee, C-R.; Lee, J. H.; Park, K. S.; Kim, Y. B.; Jeong, B. C.; Lee, S. H. Global dissemination of carbapenemase-producing Klebsiella pneumoniae: epidemiology, genetic context, treatment options, and detection methods. Front. Microbiol. [Online], 2016, 7, 895. https://doi.org/10.3389/fmicb.2016.00895.
- [2] D’Andrea, M. M.; Amisano, F.; Giani, T.; Conte, V.; Ciacci, N.; Ambretti, S.; Santoriello, L.; Rossolini, G. M. Diversity of capsular polysaccharide gene clusters in Kpc-producing Klebsiella pneumoniae clinical isolates of sequence type 258 involved in the Italian epidemic. PLoS ONE [Online] 2014, 9(5) e96827. https://doi.org/10.1371/journal.pone.0096827.