Evaluation of nitrofurantoin activity against the urinary isolates in the current scenario of antimicrobial resistance

Abstract

Introduction: Urinary tract infections (UTIs) caused by antibiotic-resistant isolates have become a major health hazard in recent years as they are very difficult to treat, causing an increase in morbidity and mortality. Nitrofurantoin has been used successfully for decades for the prophylaxis and treatment of uncomplicated cystitis but the increased emergence of antibiotic resistance has made nitrofurantoin a suitable candidate for the treatment of UTI caused by multidrug-resistant pathogens. This study was taken up with the aim to determine the activity of nitrofurantoin against the wide range of resistant urinary gram-negative and gram-positive isolates. Materials and Methods: A total of 440 nonduplicate, gram-negative, and gram-positive uropathogens obtained between July 2013 and December 2014 from 3,780 fresh midstream urine samples were subjected to the VITEK-2 compact system for identification and antimicrobial susceptibility testing. Phenotypic methods for the detection of different beta-lactamases [extended spectrum beta-lactamases, AmpC beta-lactamases, metallo-beta-lactamases, and inhibitor-resistant beta-lactamases (IRT)] and methicillin-resistance staphylococci [methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative staphylococci (MRCNS)] were employed. Results: High activity of nitrofurantoin was observed against MRCNS (96%) followed by MRSA (95%), extended spectrum beta-lactamases (ESBLs) (70%), IRT (66%), and vancomycin-resistant enterococci (VRE) (66%). However, the sensitivity rate was lowered to 38% and 32% for metallo-beta-lactamases (MBLs) and AmpC beta-lactamases, respectively. Conclusion: In view of the current incidence of antibiotic resistance among community uropathogens and based on efficacy, cost-effectiveness, and low impact on promoting resistance, nitrofurantoin should be considered as a reasonable alternative to trimethoprim-sulfamethoxazole (TMP-SMX) and fluoroquinolones for the first-line therapy of uncomplicated UTIs.