Concomitant Carbapenem and Colistin Resistance among Escherichia coli and Klebsiella pneumoniae Isolates from Patients Visiting a Hospital in Haryana, India

Background: Increasing prevalence of carbapenem resistance among Enterobacterales, particularly Escherichia coli and Klebsiella pneumoniae, poses a serious public health threat globally. Furthermore, these bacteria exhibit multidrug resistance, making treatment of infections caused by them challenging. Colistin is one of the antibiotics used in the treatment of infections caused by carbapenem resistant Enterobacterales; however, its unrestricted usage has resulted in the emergence of colistin resistant strains. The present study was conducted to determine the prevalence of carbapenem resistance and co-resistance to carbapenem and colistin resistance among E. coli and K. pneumoniae isolated from various clinical specimens from patients attending various departments of a multispecialty teaching hospital in Haryana, India. Methods: A total of 597 isolates comprising 425 E. coli and 172 K. pneumoniae isolated between March 2019 to November 2021 were included in the study. The isolates were subjected to screening for the detection of carbapenemase production using carbapenem discs and a phenotypic test, that is, the CarbaNP test. Antibiogram of the carbapenem-resistant isolates was further analyzed by the Kirby–Bauer disc diffusion method and to evaluate colistin resistance, isolates were subjected to colistin broth disc elution test. Results: The prevalence of carbapenemase production among the E. coli and K. pneumoniae isolates by the screening test were detected to be 98/425 (23.1%) for E. coli and 90/172 (52.3%) for K. pneumoniae, whereas the CarbaNP test confirmed 93/425 (21.9%) and 84/172 (48.8%) of the two categories of bacterial isolates, thus showing a false positivity rate of 2.6% (n = 11) by screening test for the detection of carbapenemase production. Among the bacterial isolates, 3 (1.7%) comprising 1 (1.1%) E. coli and 2 (2.6%) K. pneumoniae were found to be dual carbapenem- and colistin-resistant strains. K. pneumoniae isolates showed higher resistance rates to non-carbapenem antibiotics compared to E. coli isolates. Conclusions: The emergence of bacteria with concurrent resistance to carbapenems and colistin is a serious concern as they are the last-resort drugs against multidrug-resistant and extensively drug-resistant bacteria.