A Comprehensive Study of Bacterial Etiological Agents in Sterile Body Fluids and Antimicrobial Susceptibility Patterns Among Hospitalized Patients at an Academic Medical Center in India

Abstract

Background Sterile body fluids are devoid of any microbial presence, including commensal bacteria. However, bacterial invasion of these fluids can result in life-threatening infections, often leading to significant morbidity and mortality. Timely detection and precise identification of pathogens, along with antimicrobial susceptibility testing, are critical for optimizing therapeutic interventions and improving patient outcomes. Objective To study the prevalence of bacterial infections in various body fluids in hospitalized patients and to determine the antimicrobial susceptibility pattern and the phenotypic detection of extended-spectrum beta-lactamase (ESBL), metallo-beta-lactamase (MBL) and AmpC beta-lactamase producers within bacterial isolates. Materials and methods Sterile body fluid samples, excluding blood and urine, were collected and cultured at the Department of Microbiology, Krishna Institute of Medical Sciences, Western Maharashtra, India, from November 2022 to 2023. The microorganisms isolated from these fluids were identified using standard biochemical tests. Antibiotic sensitivity was assessed through the disc diffusion assay (zone of inhibition) and phenotypic identification of beta-lactamase enzymes was performed using the combined disc diffusion method. Results During the study period, 180 sterile fluid specimens were collected representing 48 cerebrospinal fluid (CSF), 53 pleural fluid, 23 peritoneal fluid, and other sterile body fluid samples. Out of these, (n=32, 17.77%) samples were culture-positive. Gram-negative bacteria were oftentimes isolated at 84% (27/32), while gram-positive were 16% (5/32). Escherichia coli was frequently isolated and (n=9, 28.12%) exhibited maximum sensitivity to gentamicin and fosfomycin (n=7, 77.78%) and maximum resistance to cefoperazone-sulbactam (n=8, 88.88%). Pseudomonas aeruginosa was isolated as the second most common organism and showed maximum susceptibility to fosfomycin (n=5, 83.34%) and maximum resistance to gentamicin, cefotaxime, cefoxitin, etc. (n=5, 83.34%). Among gram-positive isolates, coagulase-positive Staphylococcus was high in prevalence rate and (n=3, 9.37%) presented 100% sensitivity to vancomycin and maximum sensitivity to tetracycline (n=2, 66.67%) and 100% resistance to ciprofloxacin, cefoxitin, erythromycin, and other antibiotics. Among gram-negative isolates, MBL producers were 48.15%, ESBL producers were 40.74%, and 18.51% were AmpC beta-lactamase producers with a multidrug-resistant (MDR) occurrence rate of 93.75%. Conclusion Infections affecting sterile body fluids are critical due to their high mortality and morbidity rates. Timely identification of the causative organisms and their antibiotic susceptibility is essential. The prompt initiation of appropriate antibiotic therapy can decrease the duration of hospitalization and mitigate the emergence of drug resi...