Abstract

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Methicillin resistant Staphylococcus aureus (MRSA) is a pathogenic bacterium of significant importance that causes most of the hospital and community acquired infections associated with S. aureus. Methicillin resistance in strains of S. aureus is due to possession of the mecA gene or mecC gene found on a mobile genetic element (SCCmec). The virulence of MRSA is multifactorial because of the combined action of numerous virulence factors that facilitate tissue adhesion, immune evasion, and host cell injury. These virulence determinants involve both structural factors, such as surface adhesins that mediate adherence to host tissues, and secreted factors, such as enzymes, which convert host tissue into nutrients. The virulence factors of MRSA include PVL, TSST-1, Staphylococcus protein A (spa). The quorum sensing together with the global accessory regulator of Staphylococcus aureus helps control the expression of virulence gene as some are up-regulated during exponential phase of growth and down-regulated during stationary phase and vice-versa. MRSA is versatile and unpredictable. Its capacity for genetic adaptation and the serial emergence of successful epidemic strains cause it to remain a major threat to human health, further understanding of its pathogenicity trends and epidemiology will give an insight on how to tackle it’s spread.

Keywords: Pathogenicity, MRSA, S. aureus, SCCmec, virulence, genes