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.