Microbiological Profile of Pathogens Among Patients at a Tertiary Care Hospital in Mumbai, India

Antimicrobial resistance (AMR) has emerged as one of the most significant threats to global public health, compromising the effective management of infectious diseases. Institutional antibiograms provide valuable information on local pathogen distribution and antimicrobial susceptibility patterns, thereby supporting evidence-based empirical therapy and antimicrobial stewardship. This study aimed to determine the microbiological profile of pathogens and their antimicrobial susceptibility patterns among patients attending a hospital in India.

A retrospective observational study was conducted in the Department of Microbiology, Bhatia Hospital, Mumbai, Maharashtra, India. Laboratory records of culture-positive clinical specimens received between January and December 2025 were reviewed. A total of 2,075 non-duplicate, clinically significant isolates obtained from various clinical specimens were included. Bacterial and fungal isolates were identified using standard microbiological methods and the VITEK® 2 Compact system (bioMérieux, Marcy-l'Étoile, France). Antimicrobial susceptibility testing was performed using the VITEK® 2 Compact system and interpreted according to the Clinical and Laboratory Standards Institute (CLSI M100, 35th edition 2025) guidelines. Organism distribution, specimen-wise and area-wise frequency, antimicrobial susceptibility profiles, and multidrug-resistant organism (MDRO) prevalence were analysed.

A total of 2,075 clinically significant isolates were recovered during the study period. Gram-negative bacteria predominated, accounting for 1,627 (78.4%) isolates, followed by Gram-positive bacteria (299; 14.4%) and fungal isolates (149; 7.2%). The most frequently isolated pathogens were Escherichia coli (543; 26.2%), Klebsiella pneumoniae (519; 25.0%), Pseudomonas aeruginosa (328; 15.8%), Staphylococcus aureus (132; 6.4%), Candida albicans (86; 4.1%), and Acinetobacter baumannii complex (74; 3.6%). Midstream urine, sputum, wound swabs, catheter urine, pus swabs, tissue specimens, and blood samples constituted the major sources of isolates. MDROs accounted for 597 (28.8%) isolates, extended-spectrum β-lactamase (ESBL) producers were 369 (17.8%), methicillin-resistant S. aureus (MRSA) were 102 (4.9% of all isolates; 77.3% of S. aureus isolates), and vancomycin-resistant Enterococcus (VRE) accounted for 17 (0.8% of all isolates; 22.1% of Enterococcus isolates) with significantly higher prevalence of MDROs among isolates from critical care areas. Overall antimicrobial susceptibility testing demonstrated high resistance to several commonly used β-lactam antibiotics and fluoroquinolones, whereas reserve antimicrobial agents, including polymyxins, tigecycline, linezolid, glycopeptides, fosfomycin, and newer β-lactam/β-lactamase inhibitor combinations, retained comparatively better in vitro activity against susceptible isolates.

Gram-negative bacteria were the predominant pathogens isolated with a substantial burden of MDROs. The observed antimicrobial resistance patterns emphasize the need for continuous microbiological surveillance, regular updating of institutional antibiograms, and implementation of robust antimicrobial stewardship programs to optimize empirical antimicrobial therapy and improve patient outcomes.