Phenotypic Characterisation and Prevalence of Carbapenem-Resistant Enterobacterales (CRE) in Bihar, India: A Cross-Sectional Study

Background: Carbapenem-resistant Enterobacterales (CRE) infections pose a global health threat due to limited treatment options. This study aimed to determine the prevalence, phenotypic characteristics, and distribution of CRE classes in Bihar, India. Methods: A cross-sectional study was conducted from July 2021 to July 2023. CRE detection involved modified carbapenem inactivation and EDTA-modified carbapenem inactivation methods, coupled with carbapenemase inhibition tests (Combined disc tests) to classify them into various phenotypes. Antibiotic susceptibility patterns and phenotypic class distribution were determined. Statistical analysis was performed using SPSS v.23. Results: Among 3421 Enterobacterales isolates, 32.97% exhibited carbapenem resistance. Inpatients showed higher resistance (47.74%) compared to outpatients (14.48%). Resistance was prominent in respiratory (68.09%) and pus samples (56.99%). Most CRE were Escherichia coli (31.3% in pus, 22.4% in urine). Resistance to third-generation cephalosporins, BL-BLI combinations, and Aztreonam was high. Colistin resistance was observed in one isolate. Class B carbapenemases were predominant (70% in E. coli, 55% in Klebsiella pneumoniae). Co-expression of Class A and Class B carbapenemases was observed in 23% of E. coli and 36.2% of Klebsiella pneumoniae isolates. Conclusions: This study reveals a high prevalence of CRE in Bihar, India, with concerning antimicrobial resistance patterns. Class B carbapenemases predominate, warranting the development of effective interventions, including screening, isolation, hand hygiene, and antibiotic stewardship, to combat CRE's spread. Standardized phenotypic tests can guide therapy and infection control, especially in resource-limited settings. Research and development of new antibiotics are urgently needed to address this growing public health concern.