Virulence characterization of Klebsiella pneumoniae and its relation with ESBL and AmpC beta-lactamase associated resistance

Trend analysis reveals that Klebsiella pneumoniae has witnessed a steep enhancement in the antibiotic resistance and virulence over the last few decades. The present investigation aimed at a comprehensive approach investigating antibiotic susceptibility including, extended spectrum beta-lactamase (ESBL) and AmpC β-lactamase (AmpC) resistance and the prevalence of virulence genes among the K. pneumoniae isolates.

Sixty-one K. pneumoniae isolates were obtained from various clinical infections. Antimicrobial susceptibility was performed by disk diffusion method. The Mast® D68C test detected the presence of ESBLs and AmpCs phenotypically, and later presence of ESBL and AmpC genes was observed by polymerase chain reaction (PCR). Multiplex-PCR was performed to investigate various virulence genes.

Amongst 61 K. pneumoniae isolates, 59% were observed as ESBL and 14.7% as AmpC producers. All ESBL producers were positive for blaCTX-M-15, while blaCTX-M-14 was observed in 54.1% isolates. The frequency of AmpC genes was as follows: blaCMY-2 (60.7%) and blaDHA-1 (34.4%). The most frequent virulence genes were those encoding enterobactin and lipopolysaccharide. Presence of mrkD was associated with blaDHA-1 gene, while blaCMY-2 significantly (p≤0.05) correlated with the presence of iutA and rmpA virulence genes. blaDHA-1 positive isolates had urine as a significant source, while blaCMY-2 positive isolates were mainly collected from wound exudates (p≤0.05).

Our results highlight that ESBL and AmpC production along with a plethora of virulence trait on K. pneumoniae should be adequately considered to assess its pathogenesis and antibiotic resistance.