Perspectives of Methicillin-Resistant Staphylococcus Aureus (MRSA)

Staphylococcus aureus is a gram positive, nonmotile bacterium which normally colonizes in skin and mucosa of human and animal, transmitted by direct contact or via contaminated surfaces, which causes infections like skin infections , respiratory infections and food poisoning. Methicillin is a narrow spectrum betalactam antibiotic of the penicillin class which was previously used for the treatment of infections caused by Staphylococcus aureus. In 1948 it was observed that 50% of staphylococcal isolates from patients in a United Kingdom hospital were resistant to penicillin. Since then 90 to 95% strains of S. aureus were resistant to penicillin. In 1959 methicillin, a penicillinase-resistant penicillin was introduced to overcome the penicillin-resistant Staphylococcus aureus, but after few years, S. aureus strain became resistant to methicillin also and so the birth of MRSA occurred. MRSA has been detected in wide range of species including companion animal and wildlife animal. Pigs are considered to be true reservoir hosts for MRSA, causing mastitis in cattle, dogs are more infected with MRSA in comparison to cats, in horses most of the cases of MRSA infections were reported in large studs. MRSA has been isolated from wild animals like cottontail rabbit, lesser yellow migratory shore bird, Wild rat, wood mice red deer, Iberian ibex, vulture, wild boar etc. Certain facts showed that these organisms can be transferred from human to animals and from animals to humans. Most of MRSA infections are skin infections producing symptoms like cellulitis, boils, abscesses, sty, carbuncles, impetigo and rash. For the diagnosis of MRSA antimicrobial susceptibility tests (AST) such as agar disc diffusion technique is used. Cefoxitin disc diffusion is the most sensitive methods for detecting MRSA isolates showing negative and positive predictive values of 100% and 98%, respectively. For the treatment of clinical cases of MRSA, antibiotics such as trimethoprim-sulphamethoxazole, clindamycin and doxycycline, topical treatments and other measures have been used successfully.