Plant Science Research, Vol. 35, 2013

Methicillin resistant staphylococci isolated from ocular infections and their susceptibility to vancomycin, chloramphenicol and cefazolin

This study focuses on the identification of species of staphylococci causing various eye infections and prevalence of methicillin resistance among them. Detection of methicillin resistance was done by determining minimum inhibitory concentration (MIC) of oxacillin by broth microdilution against 113 staphylococcal isolates isolated from different ocular conditions. Additionally, MIC of chloramphenicol, vancomycin and cefazolin were also determined for all the isolates. The prevalence of methicillin resistance (MR) among Staphylococcus aureus (MRSA), S. epidermidis (MRSE) and coagulase negative staphylococci (MRCoNS) was 8%, 53.6% and 80% respectively. Among the three antibiotics tested, vancomycin showed the highest efficiency against both coagulase positive and negative staphylococci followed by cefazolin suggesting benefit of recycling older antibiotics such as cefazolin in the treatment of staphylococcal eye infections. Resistance to chloramphenicol was variable ranging from 40% among MRSE to 75% among MRSA. However, vancomycin should be used judiciously to prevent emergence of resistance among staphylococci causing ocular infections.