Revisiting Nitrofurantoin for Vancomycin Resistant Enterococci

Area of Science:

• Microbiology
• Infectious Diseases
• Clinical Pharmacy

Background:

• Enterococcal infections pose a significant therapeutic challenge, exacerbated by High Level Aminoglycoside Resistance (HLAR) and Vancomycin-Resistant Enterococcus (VRE).
• Limited treatment options exist for VRE infections, necessitating the exploration of alternative antimicrobial agents.
• Nitrofurantoin, an older antibiotic, has shown relatively lower resistance rates compared to other antimicrobial classes.

Purpose of the Study:

• To determine the susceptibility of nitrofurantoin against Vancomycin-Resistant Enterococcus (VRE) isolates.
• To evaluate VRE susceptibility from urinary tract infections (UTIs) in both outpatient and inpatient departments.

Main Methods:

• An observational study conducted at a tertiary care hospital in New Delhi from November 2015 to April 2016.
• Processed 14,714 urine samples to identify and confirm enterococcal isolates using standard phenotypic tests.
• Antimicrobial susceptibility testing performed using the Kirby-Bauer Disc Diffusion Method according to CLSI 2015 guidelines.

Main Results:

• A total of 70 enterococcal isolates were identified, including 9 Enterococcus faecalis and 61 Enterococcus faecium.
• Twenty-six out of 70 isolates were resistant to vancomycin (VRE).
• Eighty-four percent (21/26) of VRE isolates demonstrated susceptibility to nitrofurantoin, with both E. faecalis (80.32%) and E. faecium (88.8%) showing uniform susceptibility.

Conclusions:

• Nitrofurantoin retains significant antimicrobial efficacy against prevalent Vancomycin-Resistant Enterococcus (VRE) strains in vitro.
• Nitrofurantoin can be considered a valuable therapeutic option for treating enterococcal urinary tract infections, particularly those caused by VRE.
• The study highlights the continued utility of nitrofurantoin in the face of rising antimicrobial resistance.