Antimicrobial Susceptibility Pattern of Ceftriaxone-Sulbactam-EDTA Against Multidrug-Resistant Gram-Negative Bacilli...

Background Antibiotic therapy remains the mainstay for the management of bacterial infections. However, the rapid emergence of multidrug-resistant (MDR) organisms has become a major clinical concern, leading to limited treatment options and increased healthcare burden. Ceftriaxone-sulbactam-EDTA (CSE) is a cephalosporin-beta-lactamase inhibitor combination containing disodium edetate, an antibiotic resistance breaker that may help restore antibacterial activity against resistant Gram-negative organisms. This study aimed to evaluate CSE as a potential therapeutic option by assessing its susceptibility pattern against MDR-Gram-negative bacilli (GNB) isolated from intensive care unit patients. Material and methods A laboratory-based study was conducted on 92 MDR-GNB isolates from ICU patients at Krishna Charitable & Medical Research Centre, Karad, India. Clinical specimens, including urine, endotracheal tube secretions, sputum, pus/wound swabs, blood, and body fluids, were processed using standard microbiological methods. Bacterial isolates were identified, and antimicrobial susceptibility testing was carried out as per Clinical and Laboratory Standards Institute recommendations. Phenotypic detection of extended-spectrum beta-lactamase (ESBL), metallo-beta-lactamase (MBL), and AmpC beta-lactamase production was performed to characterize resistance mechanisms. Additionally, the susceptibility profile of MDR-GNB isolates to CSE and other commonly used antimicrobial agents was evaluated. Results The study analyzed a total of 92 MDR-GNB isolates. The highest number of isolates were observed in the 31-40 and 41-50 age groups, with male predominance. Urine was the most common specimen source, with 39 (42.39%) isolates, followed by endotracheal tube secretions, with 20 (21.74%), and sputum, with 11 (11.96%) isolates. Pseudomonas aeruginosa was the predominant organism, followed by Klebsiella pneumoniae, Klebsiella oxytoca, Acinetobacter baumannii, Escherichia coli, and Enterobacter cloacae complex. Among the isolates, 51 were ESBL producers, 48 were MBL producers, and 38 were AmpC producers, indicating a significant burden of beta-lactamase-mediated resistance. High resistance was observed against meropenem (94.57%), netilmicin (93.48%), and ciprofloxacin (90.22%). Nitrofurantoin showed good activity among urinary isolates, with 35 (89.74%) susceptible. Co-trimoxazole showed susceptibility in 6 (14.63%) of 41 tested isolates, while tigecycline showed susceptibility in 5 (12.20%) of 41 tested isolates. CSE showed substantial in vitro activity, with 80 (86.96%) isolates susceptible and 12 (13.04%) resistant. Conclusions MDR-GNBs were frequently isolated from ICU patients, mainly from urine and respiratory specimens, with P. aeruginosa and K. pneumoniae being the most common organisms. The presence of ESBL, MBL, and AmpC producers highlights the serious burden of antimicrobial resistance. CSE showed promising in vitro activity against MDR-GNB isolates and may be considered when guided by susceptibility testing. Strict infection control practices, routine resistance screening, and antimicrobial stewardship are essential in ICU settings.