Dr. M. E. Pavithra, Ph. D, Professor, Dep. of Microbiology, KMCH Institute of Health Sciences and Research, Coimbatore
Abstract: Bloodstream infections (BSIs) remain a major cause of morbidity and mortality worldwide due to the invasion of pathogenic microorganisms into the bloodstream, often resulting in sepsis, septic shock, disseminated intravascular coagulation, multiple organ dysfunction, and death. The rapid emergence of Extended-Spectrum β-Lactamase (ESBL)-producing Gram-negative bacteria has become a significant therapeutic challenge, as these enzymes confer resistance to third-generation cephalosporins and other β-lactam antibiotics, thereby limiting treatment options. This study aimed to determine the prevalence of ESBL-producing multidrug-resistant Gram-negative clinical isolates recovered from bloodstream infections using phenotypic detection methods in a tertiary care teaching hospital in Tamil Nadu. A hospital-based cross-sectional study was conducted in the Department of Microbiology, where blood culture specimens obtained from patients with suspected bloodstream infections were processed using standard microbiological techniques. Bacterial identification was performed by conventional biochemical methods, and antimicrobial susceptibility testing was carried out using the Kirby–Bauer disk diffusion method in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines. Multidrug-resistant Gram-negative isolates were screened for ESBL production by the Double Disc Synergy Test (DDST). Among the isolates recovered, Gram-positive organisms predominated, with Staphylococcus species being the most common pathogens. Among Gram-negative bacteria, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa were the frequently isolated organisms. A considerable proportion of multidrug-resistant Escherichia coli and Klebsiella pneumoniae isolates were confirmed as ESBL producers, demonstrating high resistance to third-generation cephalosporins while retaining comparatively better susceptibility to carbapenems and selected aminoglycosides. The findings highlight the growing burden of ESBL-producing pathogens causing bloodstream infections in Tamil Nadu and emphasize the importance of routine phenotypic detection, continuous antimicrobial resistance surveillance, implementation of antimicrobial stewardship programs, and institution-specific antibiotic policies. Early diagnosis and timely initiation of appropriate antimicrobial therapy are crucial to improving clinical outcomes and reducing the spread of multidrug-resistant organisms.
Keywords: Bloodstream infection, Extended-Spectrum β-Lactamase, ESBL, Multidrug-resistant bacteria, Escherichia coli, Klebsiella pneumoniae, Phenotypic detection, Double Disc Synergy Test, Antimicrobial resistance
Citation: To be assigned
DOI: To be assigned
Article Information
- Received: 15/07/2026
- Revised: 02/08/2026
- Accepted: 8/08/2026
- Published: 16/08/2026
Full Article