Role of CRISPR-cas system on virulence traits and carbapenem resistance in clinical Klebsiella pneumoniae isolates.

BACKGROUND AND OBJECTIVES

The bacterial adaptive immune system known as CRISPR-Cas (clustered regularly interspersed short palindromic repeats-CRISPR-associated protein) is engaged in defense against various mobile genetic elements (MGEs) such as plasmids and bacteriophages. The purpose of this study was to characterize the CRISPR-Cas systems in carbapenem-resistant Klebsiella pneumoniae isolates and assess any possible correlation between these systems with antibiotic susceptibility, biofilm formation, and bacterial virulence.

MATERIALS AND METHODS

A total of 156 CRKP isolates were collected from different specimens of the inpatients. Biofilm formation and antibiotic susceptibility testing were evaluated using standard methods. Furthermore, the CRISPR-Cas system subtype genes, 11 carbapenemase genes, and 17 virulence genes were identified using separate standard PCR reactions. The diversity of the isolates was determined by random amplified polymorphic DNA (RAPD)-PCR.

RESULTS

The development of biofilms and antibiotic susceptibility of several CRKP isolates were significantly correlated with the absence or presence of the CRISPR-Cas system. PCR analysis of carbapenemase genes revealed that the frequency of the bla gene was significantly higher in the isolates with the subtype I-E CRISPR-Cas system. Moreover, the isolates with the subtype I-E CRISPR-Cas system exhibited a propensity to possess more virulence genes such as allS, k2A, wcaG, aerobactin, rmpA, iroN, magA, rmpA2, kfu, iutA, iucB, ybtS, repA, and terW.

CONCLUSION

CRISPR-Cas systems could affect the antibiotic susceptibility, capacity for biofilm formation, and virulence of Klebsiella pneumoniae. Our findings showed that the isolates containing the CRISPR-Cas system were moderate or strong biofilm producers and had a higher frequency of virulence genes.