Description

INTENDED USE

For the isolation and cultivation of methicillin-resistant Staphylococcus aureus (MRSA).

PRINCIPLE

Staphylococcus aureus is a common bacterium found on the skin of healthy people. It is responsible for infections ranging from superficial to systemic (1,2). Staphylococcus aureus resistant to the antibiotic methicillin is referred to as Methicillin Resistant Staphylococcus aureus (MRSA) (3). The proportions of both hospital-acquired and community-acquired infections caused by MRSA have steadily been increasing worldwide. Initially, staphylococcal infections were treated using penicillin. But over the years, resistance to penicillin developed, so methicillin was the next drug of choice. Unfortunately, certain strains (MRSA) have now developed resistance to methicillin also. Patients with breaks in their skin due to wounds, indwelling catheters or burns are those with certain risk of developing MRSA infection (4).

Symptoms in serious cases may include fever, lethargy and headache. MRSA can cause UTI, pneumonia, toxic shock syndrome and even death. Spread of MRSA infections can be controlled to a great extent by maintaining personal hygiene after interaction with an MRSA infected person (3). Methicillin-resistant strains of Staphylococcus aureus (MRSA) were recognized in 1980’s as a major clinical and epidemiological problem. MRSA strains were heterogeneous in their expression of resistance to β- lactam agents, in that large differences in the degree of resistance were seen among the individual cells in a population. The basis of methicillin-resistance is the production of an additional penicillin-binding protein mediated by the mec A gene, an additional gene found in methicillin-resistant Staphylococci. Tryptone, Peptone, dextrose provides nitrogen, carbon compounds, long chain amino acids and other essential growth nutrients. Sodium chloride maintains the osmotic equilibrium of the medium as well as supports the growth of Staphylococcus species. Selective Supplement for MRSA (FD299) is used for the selective growth of MRSA. It contains cefoxitin which is principally aimed at inducing the expression of methicillin resistance (5) and inhibiting the growth of Methicillin Sensitive Staphylococcus aureus (MSSA). The supplement also contains aztreonam to inhibit most isolates of the family Enterobacteriaeceae and colistin which is active against Pseudomonas species.