Genetic and Functional Analysis of the <i>pks</i> Gene in Clinical Klebsiella pneumoniae Isolates

Abstract

The <i>pks</i> gene cluster encodes colibactin, which can cause DNA damage and enhance the virulence in Escherichia coli. However, the role of the <i>pks</i> gene in Klebsiella pneumoniae has not been fully discussed. The aim of this study was to analyze the relationship between the <i>pks</i> gene cluster and virulence factors, as well as to assess antibiotic resistance and biofilm formation capacity in clinical isolates of Klebsiella pneumoniae. Thirty-eight of 95 clinical K. pneumoniae strains were <i>pks</i> positive. <i>pks</i>-positive strains usually infected emergency department patients, and <i>pks</i>-negative strains often infected hospitalized patients. The positive rates of K1 capsular serotype and hypervirulence genes (<i>peg-344</i>, <i>rmpA</i>, <i>rmpA2</i>, <i>iucA</i>, and <i>iroB</i>) were significantly higher in the <i>pks</i>-positive isolates than the <i>pks</i>-negative isolates (<i>P</i> < 0.05). The biofilm formation ability of <i>pks</i>-positive isolates was stronger than that of <i>pks</i>-negative isolates. Antibacterial drug susceptibility test showed the resistance of <i>pks</i>-positive isolates was weaker than that of <i>pks</i>-negative isolates. In conclusion, patients with <i>pks</i>-positive K. pneumoniae infection might have worse treatment outcomes and prognosis. <i>pks</i>-positive K. pneumoniae might have stronger virulence and pathogenicity. Clinical infection with <i>pks</i>-positive K. pneumoniae needs further attention. <b>IMPORTANCE</b> The infection rate with <i>pks</i>-positive K. pneumoniae has been increasing in recent years. Two previous surveys in Taiwan reported 25.6% <i>pks</i> gene islands and 16.7% <i>pks</i>-positive K. pneumoniae strains in bloodstream infections, and Chinese scholars also did a survey of K. pneumoniae bloodstream infections in Changsha, China, and found 26.8% <i>pks</i>-positive K. pneumoniae. In addition, it was found that the <i>pks</i> gene cluster might encode colibactin, which could be related to the virulence of K. pneumoniae. Studies confirmed that the prevalence of colibactin-producing K. pneumoniae was increasing. It is necessary to consider the clear relationship between the <i>pks</i> gene cluster and high pathogenicity in K. pneumoniae.