Phenotypic Detection of Metallo-β-Lactamase Production and Antimicrobial Susceptibility Patterns Among Multidrug-Resistant Klebsiella spp. Isolated From Intensive Care Units: A Prospective Observational Study

BackgroundThe rapid emergence of multidrug-resistant (MDR) and metallo-β-lactamase (MBL)-producing Klebsiella species presents a critical therapeutic challenge in critical care settings.These opportunistic pathogens significantly compromise treatment outcomes in intensive care units (ICUs) by disabling last-line carbapenem antibiotics.This study was conducted to evaluate the age, gender, and ICU-wise distribution of Klebsiella spp.clinical isolates, determine their antimicrobial resistance profiles, and compare the efficacy of three phenotypic screening methods for MBL detection. Material and methodsThis prospective, observational study was conducted from December 2023 to December 2025 in the department of microbiology, in collaboration with the ICUs of a tertiary care hospital.A total of 146 nonduplicate Klebsiella spp.isolates recovered from various clinical specimens (including endotracheal tube aspirates, urine, sputum, blood, and pus) were included.Identification was performed using standard biochemical profiles, and antimicrobial susceptibility testing (AST) was carried out via the Kirby-Bauer disc diffusion method following Clinical and Laboratory Standards Institute (CLSI) guidelines.All 146 MDR Klebsiella spp.isolates were evaluated using three phenotypic methods for MBL detection: the imipenem-EDTA (ethylenediaminetetraacetic acid) combined disc test (CDT), the ceftazidime-EDTA CDT, and the imipenem-EDTA double-disc synergy test (DDST). ResultsAmong the 146 isolates, 92 (63.01%) were obtained from male patients, and the highest number of isolates was observed in the 41-60-year age group (55/146; 37.67%).The medical intensive care unit (MICU) was the ICU with the highest number of isolates, accounting for 96 (65.75%) of the 146 isolates.The antimicrobial susceptibility results showed high resistance to several tested antibiotics.The imipenem-EDTA CDT yielded 111 positive results, the ceftazidime-EDTA CDT yielded 102, and the imipenem-EDTA DDST yielded 95 positive results.These findings represent the observed results of the respective phenotypic methods and do not establish their diagnostic sensitivity or superiority. ConclusionThe study describes the antimicrobial susceptibility patterns and phenotypic MBL detection results among MDR Klebsiella spp.isolated from ICU patients.The imipenem-EDTA CDT produced the highest number of positive results among the three evaluated methods.However, the findings do not establish diagnostic sensitivity or superiority because no independent reference standard or molecular confirmation was used.Further evaluation using an appropriate reference standard is needed.