Abstract
The pks gene cluster encodes enzymes responsible for the synthesis of colibactin, a genotoxin that has been shown to induce DNA damage and contribute to increased virulence. The present study investigated the prevalence of pks in clinical K. pneumoniae isolates from a national surveillance program in Taiwan, and identified microbiological and molecular factors associated with pks-carriage. The pks gene cluster was detected in 67 (16.7%) of 400 isolates from various specimen types. Multivariate analysis revealed that isolates of K1, K2, K20, and K62 capsular types (p < 0.001), and those more susceptible to antimicrobial agents (p = 0.001) were independent factors strongly associated with pks-carriage. Phylogenetic studies on the sequence type (ST) and pulsed-field gel electrophoresis patterns indicated that the pks-positive isolates belong to a clonal group of ST23 in K1, a locally expanding ST65 clone in K2, a ST268-related K20 group, and a highly clonal ST36:K62 group. Carriage of rmpA, iutC, and ybtA, the genes associated with hypervirulence, was significantly higher in the pks-positive isolates than the pks-negative isolates (95.5% vs. 13.2%, p < 0.001). Further studies to determine the presence of hypervirulent pks-bearing bacterial populations in the flora of community residents and their association with different disease entities may be warranted.
Highlights
Colibactin, a hybrid peptide-polyketide genotoxin, was first identified in extraintestinal pathogenic E. coli strain IHE303423
The pks gene cluster encodes enzymes that are responsible for the synthesis of colibactin, a genotoxin that has been shown to induce host DNA damage, may contribute to other disease entities and increased virulence in E. coli and K. pneumoniae[27,30]
The present study showed that the prevalence of the pks colibactin gene cluster among clinical K. pneumoniae isolates from multiple hospitals in different regions of Taiwan was 16.7%
Summary
Colibactin, a hybrid peptide-polyketide genotoxin, was first identified in extraintestinal pathogenic E. coli strain IHE303423. According to a study in Europe, the pks colibactin gene cluster was detected in 34% of E. coli strains of phylogenic lineage B2, but only in 3.5% of K. pneumoniae clinical isolates[25]. Sequencing of K. pneumoniae strain 1084 from Taiwan revealed the presence of a pks gene cluster that is identical to the E. coli IHE3034 version[26]. A high prevalence (25.6%) of the pks colibactin gene cluster was found among K. pneumoniae clinical isolates, a rate significantly higher than the 3.5% found in a recent European survey[25]. The present study was carried out to investigate the prevalence of the pks colibactin gene cluster in K. pneumoniae clinical isolates from a multicenter national surveillance program[29]. Microbiological and molecular characterizations were performed to identify factors associated with pks gene cluster carriage
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