Alarming colistin and carbapenem resistance in Klebsiella pneumoniae: molecular insights from Tehran hospitals, Iran

Colistin showed the highest efficacy, with susceptibility rates of 83.3%. Notably, 25 isolates (16.7%) were colistin-resistant and 115 (76.7%) were carbapenem-resistant. Phenotypic analysis identified 87 (57.3%) isolates as ESBL producers, 93 (62%) as carbapenemase producers, and 79 (52.7%) as MBL producers. Biofilm production levels were categorized as strong (44 isolates, 29.3%), moderate (56, 37.3%), and weak (50, 33.3%). The spectrum of detected resistance genes included blaTEM (117, 78%), blaSHV (74, 49.3%), blaCTX-M (121, 80.7%), blaNDM (71, 47.3%), blaOXA-48 (44, 29.3%) and blaVIM (4, 2.7%), whereas blaGES, blaPER, blaVEB, blaIMP, blaKPC, and mcr-1 to mcr-4 genes were not detected in any isolates. These findings underscore the critical need for comprehensive surveillance and stringent infection control measures to prevent the spread of resistant K. pneumoniae strains in healthcare facilities.