Carbapenem resistance and carbapenemase production among Gram-negative uropathogens at a tertiary care hospital in Kathmandu, Nepal

Carbapenems are the last-resort agents for complicated urinary tract infections (UTIs) caused by Gram-negative bacteria, but increasing resistance threatens their effectiveness. This cross-sectional study assessed imipenem (IPM) and meropenem (MEM) resistance among Gram-negative uropathogens and evaluated carbapenemase production in carbapenem-resistant Klebsiella pneumoniae isolates at a tertiary care hospital in Kathmandu, Nepal. Midstream urine specimens were collected from patients with suspected UTIs. Bacterial isolates were identified using standard microbiological methods, including morphological, cultural, and biochemical characterization. Antimicrobial susceptibility of Gram-negative isolates was tested by the Kirby-Bauer disk diffusion method. Carbapenem-resistant Klebsiella pneumoniae isolates were further evaluated for carbapenemase production using the modified carbapenem inactivation method (mCIM), according to CLSI guidelines. Of the 550 urine specimens, 95 (17.3%) yielded significant bacterial growth, comprising 87 (91.6%) Gram-negative and 8 (8.4%) Gram-positive isolates, with K. pneumoniae and Escherichia coli being the predominant Gram-negative uropathogens. Carbapenem resistance was detected in 17.2% (15/87) of Gram-negative isolates, with all resistant isolates showing concordant resistance to imipenem and meropenem. Among these carbapenem-resistant isolates, 93.3% (14/15) were K. pneumoniae , whereas one (6.7%) was E. coli. Within individual species, resistance was detected in 36.8% (14/38) of K. pneumoniae and 3.0% (1/33) of E. coli isolates. A significant association was observed between bacterial species and carbapenem resistance ( p = 0.003). Carbapenemase production was detected in 71.4% (10/14) of carbapenem-resistant K. pneumoniae isolates tested by mCIM. Carbapenem resistance was observed among Gram-negative uropathogens, with K. pneumoniae accounting for most resistant isolates. The detection of carbapenemase-producing K. pneumoniae highlights the need for ongoing surveillance, antimicrobial stewardship, along with molecular characterization of resistant isolates.