Analysis on the resistance of clinically cefoxitin-non-susceptible Klebsiella pneumoniae isolates and prevalence of β-lactamase

Objective To analyze the resistance of clinically cefoxitin-non- susceptible Klebsiella pneumoniae isolates and the prevalence ofβ- lactamase. Methods WHONET 5. 6 was used to analyze the resistance of 62 strains with non- susceptibility to cefoxitin recovered. Chi-square test was adopted to compare the resistance rates of 62 isolates with the 239 Klebsiella pneumoniae isolates susceptible to cefoxitin collected during the same period. Meanwhile,the 62 clinical isolates were further taken for preliminary screening for ESBLs and carbapenmase by disk-diffusion tests and modified Hodge tests,respectively. Further analysis for detecting the resistant genes encoding AmpC and carbapenemase was carried out by PCR and DNA sequencing. Results On the whole,cefoxin- non- susceptible Klebsiella pneumoniae isolates displayed higher resistances towards all the antimicrobial agents tested( P 0. 05),except for ampicilin. Preliminary screening test showed that 55strains( 88. 7%) were ESBLs producers and 39 strains( 62. 9%) were carbapenemase producers. PCR and DNA sequencing showed that 8( 12.9%) produced AmpC and 39( 62.9%) strains produced KPC carbapenemase,respectively. Conclusion Most of the Klebsiella pneumoniae isolates non- susceptibilitible to cefoxitin produce KPCcarbapenemase and ESBLs,with AmpC being prevalent,posing a great challenge to clinical therapy and infection control.