Pyrosequencing-based analysis reveals a novel capsular gene cluster in a KPC-producing Klebsiella pneumoniae clinical isolate identified in Brazil

Abstract

BackgroundAn important virulence factor of Klebsiella pneumoniae is the production of capsular polysaccharide (CPS), a thick mucus layer that allows for evasion of the host's defense and creates a barrier against antibacterial peptides. CPS production is driven mostly by the expression of genes located in a locus called cps, and the resulting structure is used to distinguish between different serotypes (K types). In this study, we report the unique genetic organization of the cps cluster from K. pneumoniae Kp13, a clinical isolate recovered during a large outbreak of nosocomial infections that occurred in a Brazilian teaching hospital.ResultsA pyrosequencing-based approach showed that the cps region of Kp13 (cpsKp13) is 26.4 kbp in length and contains genes common, although not universal, to other strains, such as the rmlBADC operon that codes for L-rhamnose synthesis. cpsKp13 also presents some unique features, like the inversion of the wzy gene and a unique repertoire of glycosyltransferases. In silico comparison of cpsKp13 RFLP pattern with 102 previously published cps PCR-RFLP patterns showed that cpsKp13 is distinct from the C patterns of all other K serotypes. Furthermore, in vitro serotyping showed only a weak reaction with capsular types K9 and K34. We confirm that K9 cps shares common genes with cpsKp13 such as the rmlBADC operon, but lacks features like uge and Kp13-specific glycosyltransferases, while K34 capsules contain three of the five sugars that potentially form the Kp13 CPS.ConclusionsWe report the first description of a cps cluster from a Brazilian clinical isolate of a KPC-producing K. pneumoniae. The gathered data including K-serotyping support that Kp13’s K-antigen belongs to a novel capsular serotype. The CPS of Kp13 probably includes L-rhamnose and D-galacturonate in its structure, among other residues. Because genes involved in L-rhamnose biosynthesis are absent in humans, this pathway may represent potential targets for the development of antimicrobial agents. Studying the capsular serotypes of clinical isolates is of great importance for further development of vaccines and/or novel therapeutic agents. The distribution of K-types among multidrug-resistant isolates is unknown, but our findings may encourage scientists to perform K-antigen typing of KPC-producing strains worldwide.

Population Structure of KPC-Producing Klebsiella pneumoniae Isolates from Midwestern U.S. Hospitals

“…The cps locus in ST258b strains has one nucleotide difference from the wzi-81 allele in the typing scheme of Brisse et al (16) and bears rhamnoseutilizing genes. The cps locus in these strains was most similar to that in the bla KPC-2 -producing Kp13 strain from Brazil (17,18) and clade 2 strains in reference 8, cps in reference 19, and to the cps locus in the KPNIH strains, with more than 99.99% nucleotide identity throughout the 50-kb region. The cps locus in ST258a strains (wzi-29) was nearly identical to the cps locus in the ST258 clade 1 (8), in VA360 (ANGI00000000), a bla KPC-2 ST258 strain from Ohio, in KpMDU1 (AMWO00000000), a bla KPC-2 strain from Australia, and to cps 207-2 (19).…”

Expansion and Evolution of a Virulent, Extensively Drug-Resistant (Polymyxin B-Resistant), QnrS1-, CTX-M-2-, and KPC-2-Producing Klebsiella pneumoniae ST11 International High-Risk Clone

“…These virulence factors could promote and partly explain the epidemiological success of ST11. Unfortunately, these advantageous traits have not been researched extensively, and few reports regarding the pathogenic potential and virulence factors of KPC-producing K. pneumoniae have been published (8,(47)(48)(49), reflecting a lack of knowledge of the epidemiologic scenario and prospects for medical prognosis.…”

Multiplex PCR for Identification of Two Capsular Types in Epidemic KPC-Producing Klebsiella pneumoniae Sequence Type 258 Strains

“…One epidemiologically important finding was that ST258 strains carry two distinct cps gene clusters. One cps gene cluster is highly similar to that from a KPC-producing K. pneumoniae strain, Kp13 (cps Kp13 ), an ST442 clinical isolate obtained from a patient in southern Brazil in 2009 (5,6). The second cps gene cluster is novel, harboring several unique genes compared to others in GenBank (ncbi.nlm .nih.gov/GenBank/).…”