Vancomycin resistance and biofilm formation among methicillin resistant coagulase negative staphylococci isolated from conjunctivitis

Fifteen isolates of methicillin resistant coagulase negative staphylococci (MRCONS) recovered from fifteen cases of bacterial conjunctivitis were tested for their susceptibilities to ten antibiotics, by disc diffusion method, the extent of their susceptibilities to vancomycin by agar dilution method and, their capability for producing biofilm. Multiple antibiotic resistances were clearly recognized among all MRCONS and one strain was found resistant to all antibiotics. Six out of the 15 strains (40 %) exhibited intermediate resistance to vancomycin (8-16 μg / ml) and one isolate (6.7 %) recovered from adult age group was fully resistant to vancomycin (32 μg / ml). Biofilm production was expressed by 11 out of the 15 strains. These constituted seven isolates of VRCONS (100 %) and four isolates out of MRCONS (50 %). The association between biofilm formation and antibiotic resistance reflects clinical significance of these isolates and the need for determination of antibiotic susceptibility directly against biofilm-associated organisms.