• Tayyeba Saba, Muhammad Sajid, Amir Afzal Khan, and Rabaab Zahra.
• Tayyeba Saba, M.Phil, Department of Microbiology, Quaid-i-Azam University, Islamabad, Pakistan.
• Pak J Med Sci. 2018 May 1; 34 (3): 633-637.

ObjectiveTo determine the role of icaAD and agr genes in biofilm formation and evaluate the consistency of two phenotypic methods for biofilm measurement.MethodsA total of 81 clinical S. aureus strains were included and analyzed for biofilm formation by two methods. The microtitration plate method was optimized using computational fluid dynamics and compared with the Congo red assay. The genes for icaAD and agr were detected using PCR.ResultsOf 81 isolates, biofilm production was detected in 43% isolates using Congo red method while microtiter plate assay showed biofilm production in 92% isolates. Both methods showed correlation in 30% isolates. PCR detection showed icaAD gene in 42 (52%) isolates. Out of 81 S. aureus isolates 65 strains (80%) contained agr while 16 (20%) strains were non-typeable.ConclusionsIn conclusion, biofilm production was observed for both agr positive and agr negative isolates. Furthermore, the presence of icaAD genes was not associated with all biofilm producing strains as some strains negative for icaAD genes displayed biofilm production.

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