Antimicrobial Resistance Patterns and Molecular Characterisation of Gram-negative Non Fermenters: A Cross-sectional Study from Odisha, India

Introduction: Non fermenting Gram-negative Bacilli (NFGNB) are emerging as major opportunistic pathogens in healthcare settings. NFGNB are intrinsically resistant to many antibiotics and can survive in harsh conditions. Aim: To investigate antimicrobial resistance patterns and perform molecular characterisation of NFGNB isolated from clinical samples in order to understand resistance mechanisms and epidemiological distribution. Materials and Methods: This cross-sectional study was conducted from September 2021 to October 2023 at SCB Medical College, Cuttack, Odisha, India. A total of 920 clinical samples from various body fluids were collected from both inpatients and outpatients across hospital departments and analysed using bacteriological and molecular methods. Standard protocols were followed for sample processing, culture, and species identification. Antibiotic susceptibility testing was performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines using appropriate quality control strains. Extended-Spectrum Beta-Lactamase (ESBL) and Metallo-Beta-Lactamase (MBL) detection was carried out using phenotypic methods (disc diffusion and E-test) and genotypic techniques Polymerase Chain Reaction (PCR) targeting TEM, SHV, and CTX-M genes). Demographic variables included age and sex distribution of enrolled patients. Data were analysed using Chi-square tests, with p-value<0.05 considered statistically significant. Results: Of the 920 clinical samples analysed, 159 (17.3%) were positive for NFGNB. The predominant isolates were Pseudomonas aeruginosa (96; 60.37%) and Acinetobacter baumannii (48; 30.18%). Among NFGNB-positive cases, males (111; 69.81%) were more frequently affected than females (48; 30.19%). The highest number of cases occurred in the 31-40-year age group (42; 26.41%), followed by 21-30 years (32; 20.12%) and 41–50 years (25; 15.72%). TEM showed 86 isolates (54.08%), indicating a high prevalence of resistance. Conclusion: Pseudomonas aeruginosa and Acinetobacter baumannii were the predominant NFGNB isolates, exhibiting high levels of multidrug resistance and ESBL production. Emerging carbapenem resistance highlights the urgent need for continuous surveillance and strengthened infection control measures. Targeted combination therapy guided by susceptibility testing is essential for effective clinical management.