A Comparative In Vitro Sensitivity Study of "Ceftriaxone-Sulbactam-EDTA" and Various Antibiotics against Gram-negative Bacterial Isolates from Intensive Care Unit

Introduction: A rapid increase in multidrug-resistant (MDR) strains is being seen across the globe especially in the Southeast Asian region, including India. Carbapenems and colistin form the mainstay of treatment against gram-negative pathogens, especially extended-spectrum beta-lactamase (ESBL)- and metallo-beta-lactamse (MBL)-producing isolates. However, due to increased resistance to carbapenems and toxicity of colistin, especially in intensive care units (ICUs), carbapenem-sparing antibiotics like ceftriaxone-sulbactam-EDTA (CSE) combination needs to be evaluated.

Materials and methods: Bacterial isolates cultured from various clinical samples from all ICUs for a period of 9 months were evaluated. Bacterial identification was performed by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) and antibiotic susceptibility testing were performed by disk diffusion and E test method. Antibiogram of various antibiotics was noted. Extended-spectrum beta-lactamase- and MBL-producing bacteria were identified by phenotypic methods. Antibiotic sensitivity results of CSE were compared with the comparator drugs like colistin, carbapenems, and tigecycline in Enterobacteriaceae, Acinetobacter spp., and Pseudomonas spp. along with ESBL and MBL producers.

Results: A total of 2,760 samples of blood, cerebrospinal fluid (CSF), respiratory samples, tissue, and pus were collected from ICUs with maximum isolates from pus (37%) followed by respiratory samples (31%) and blood (27%). Escherichia coli and Klebsiella pneumoniae were the predominant gram-negative pathogens accounting for 56% of the isolates followed by Acinetobacter spp. (23%) and Pseudomonas spp. (15%). Extended-spectrum beta-lactamase screening was positive for 57% (1,069/1,877) isolates; whereas 43% (732/1,877) were MBL producers. According to the antibiotic susceptibility results, CSE was the most effective antibiotic showing 94% sensitivity for carbapenem-sensitive Enterobacteriaceae and 97% for carbapenem-resistant Acinetobacter and Pseudomonas spp. Among the other drugs, colistin was found to be the most effective showing almost 95% sensitivity in both the Enterobacteriaceae and non-Enterobacteriaceae group (both ESBL + OXA/NDM). Ceftriaxone-sulbactam-EDTA was also found much more effective (95%) as compared to Colistin (89%) toward ESBL- and MBL-producing strains of Enterobacteriaceae and non-Enterobacteriaceae group. Among the carbapenems, imipenem was the most effective drug against Enterobacteriaceae showing 34% sensitivity and ertapenem proved to be least effective.

Conclusion: In our present study, CSE emerged as a potent antibacterial agent against MDR gram-negative infections; both for ESBL as well as MBL producers. Hence, in light of present study, we strongly recommend inclusion of CSE in routine sensitivity panel and may be used as a carbapenem- and colistin-sparing drug and a promising option against ESBL and MBL producers especially in ICU.

How to cite this article: Singh S, Sahu C, Patel SS, Singh A, Yaduvanshi N. A Comparative In Vitro Sensitivity Study of "Ceftriaxone-Sulbactam-EDTA" and Various Antibiotics against Gram-negative Bacterial Isolates from Intensive Care Unit. Indian J Crit Care Med 2020;24(12):1213-1217.