Abstract
Objective:To determine the role of icaAD and agr genes in biofilm formation and evaluate the consistency of two phenotypic methods for biofilm measurement.Methods:A 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.Results:Of 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.Conclusions:In 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.
Highlights
Staphylococcus aureus (S. aureus) is an important human pathogen which causes both hospital1
One study demonstrated that 78% of S. aureus were biofilm positive[19], while another showed that 83.3% of S. aureus were biofilm producers.[8]
Biofilm-positive phenotype was exhibited by 57.8% of Staphylococcal clinical isolates and high and moderate biofilm formation was displayed by 14.47% and 39.4% strains, respectively while weak or no biofilm was detected in 46% isolates.[7]
Summary
Staphylococcus aureus (S. aureus) is an important human pathogen which causes both hospital. S. aureus so it is important to have reliable method for the early detection of biofilm forming strains.[6]. In S. aureus accessory gene regulator (agr) locus encodes the quorum sensing system which plays an important role in biofilm formation and has been shown to slow down biofilm formation.[11,12] S. aureus strains having no agr group can form strong biofilm.[12,13] When biofilm has formed activation of agr system is required for detachment of biofilm. In view of importance of infections associated with biofilm formation, the aim of this study was to determine biofilm producing ability of clinical Staphylococcus aureus and to evaluate reliability of phenotypic methods
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