A surveillance study of multidrug-resistant organisms among clinically significant Gram-negative bacteria in a tertiary care teaching hospital from South India

Background: Sparse published data are available from Andhra Pradesh the burden of multidrug-resistant (MDR) Gram-negative bacteria in clinical specimens. Methods: We studied the burden of MDR Gram-negative bacteria from among various clinical specimens in our tertiary care teaching institute. Results: A total of 6900 isolates were obtained of which 2960 organisms were MDR. Escherichia coli were the most frequently isolated Gram-negative species (37%), followed by Klebsiella spp. (13.4%). Pseudomonas aeruginosa, Acinetobacter spp. and Enterobacter spp. were the other commonly isolated Gram-negative organisms. High resistance rates were observed for all antimicrobials studied except for cefoperazone-sulbactam (62.6%), meropenem (70%), aminoglycosides (64%) and polymyxin B (98.6%). In spite of high resistant rates (>50%) for ciprofloxacin (80%), cephalosporins (74.4%) and cotrimoxazole (65.7%), the above-mentioned antimicrobials were clinically effective. Extended-spectrum β-lactamase production was one of the significant mechanisms of resistance in our study as β-lactam resistance was 74.4%. Conclusions: Our study documents a high proportion of resistant Gram-negative organism isolates. Clinicians should consider this while initiating antibiotic treatment.