Bacteriological Study of Pathogenic Staphylococci with Special Reference to Vancomycin Susceptibility

Staphylococci are one of the most frequently isolated organisms in microbiology laboratory from a variety of clinical specimens. Invasive Staphylococcal disease had mortality rate of about 90%, before the advent of wonder drug Penicillin in 1940. How ever in 1942, resistance was described and by 1960′s resistance to semi synthetic penicillins like Methicillin & Oxacillin was observed. Methicillin-resistant Staphylococcus aureus resistant to all antibiotics including Vancomycin has been reported in Japan, USA, Canada and Brazil. Vancomycin has been widely used in the treatment of infections caused by Methicillin-Resistant Staphylococcus Aureus (MRSA). The emergence of Vancomycin Intermediate and Resistant Staphylococcus aureus (VISA and VRSA, respectively) in various parts of the world has been of great concern in clinical settings.

This study was performed to evaluate the possible presence of VISA and VRSA at Andhra Medical College, Visakhapatnam.

The present study was conducted in the Department of Microbiology. MRSA strains were tested for Vancomycin susceptibility by standard Kirby-Bauer disc diffusion method, agar dilution method and by E-test according to standards of NCCLS

Using disk diffusion test, most isolates were resistant to penicillin, while three of the isolates had Vancomycin MIC of 8 g/ml. All the 3 VISA strains showed multi drug resistance indicating the need to create awareness regarding these strains in the local scenario.