Evaluation of Susceptibility of Glycopeptide-resistant and Glycopeptide-sensitive Enterococci to Commonly Used Biocides in a Super-speciality Hospital: A Pilot Study

CONTEXT: Although existence of a probable association between glycopeptide and biocide resistance among enterococci has often been hypothesized, all studies conducted so far on this subject have been inconclusive. AIMS: The aim of this study was to explore the possibility of the existence of an association between glycopeptide resistance and reduced susceptibility to biocides among Enterococcus spp. SETTINGS AND DESIGN: This was a pilot study conducted in a super-speciality hospital situated in New Delhi, India, between June and November, 2015. PATIENTS AND METHODS: Fourteen isolates of Enterococcus spp. obtained from various clinical samples of inpatients were subjected to susceptibility testing by modified Kirby-Bauer disk diffusion method to the following antibiotics: ampicillin (30 μg), gentamicin (120 μg), linezolid (30 μg), teicoplanin (30 μg), and vancomycin (30 μg). Based on the preliminary glycopeptide susceptibility results, all the isolates were classified into glycopeptide-sensitive and glycopeptide-resistant groups, respectively. Isolates belonging to both of these groups were subjected to tube dilution method for determining minimum inhibitory concentration of three biocides, namely, sodium hypochlorite, povidone-iodine, and absolute ethanol, respectively. Minimum bactericidal concentration of these disinfectants was also determined as per standard guidelines. STATISTICAL ANALYSIS USED: Not applicable. RESULTS: More number of glycopeptide-sensitive strains exhibited reduced susceptibility to sodium hypochlorite than glycopeptide-resistant strains of enterococci. However, more number of glycopeptide-resistant isolates exhibited lower susceptibility to povidone-iodine than glycopeptide-sensitive isolates of enterococci. Both glycopeptide-sensitive and glycopeptide-resistant enterococci were equally susceptible to absolute ethanol. CONCLUSIONS: It seems that biocide resistance is an important issue and may have links with antibiotic resistance. This study points towards a possible association between glycopeptide resistance and reduced susceptibility to povidone iodine among enterococci. More studies should be conducted in order to further explore this supposedly enigmatic issue.