Numan Javed, Nadeem Afzal, Romeeza Tahir, Afia Abbas


Background: Staphylococcus aureus is a gram positive bacterium that causes a number of diseases
such as abscesses, infective endocarditis, septic arthritis, etc. It is acquiring resistance against many
antibiotics like methicillin; therefore its control is becoming increasingly difficult. Peripheral blood
phagocytes particularly polymorphonuclear leucocytes play an important role in the protective
mechanisms against these organisms. Phagocytes interact with bacteria and phagocytose these
microorganisms to kill them. Methods: Phenotypically different isolates of Staphylococcus aureus
including methicillin resistant Staphylococcus aureus (MRSA) and methicillin sensitive
Staphylococcus aureus (MSSA) were collected from various hospitals of Lahore, Pakistan. Fresh
polymorphonuclaer leucocytes were obtained from healthy individuals by centrifugation using FicolHypaque gradient combined with dextran sedimentation. Microbiological method was used for the
determination of phagocytic index of phenotypic variants of Staphylococcus aureus. Results: A
significant difference was observed between the phagocytic index of both bacterial groups. MSSA
group showed the Mean±SD of 79.46%±3.9 while MRSA group showed 72.35%±2.5. Conclusion:
Significant difference in phagocytic index indicates that it can be one of the mechanisms of MRSA
to evade host immune system as compare to MSSA.
Keywords: MRSA, MSSA, Phagocytic index, Polymorphonuclear leucocytes

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