The association between vancomycin resistance level and the virulence in clinical Staphylococcus aureus isolates / Mayada Elhusseiny Ibrahim Bakr ; Supervised Mohamed Abdelhalim Ramadan , Alaa Eldien Mahmoud Shawky Hosny , Mona Tawfik Kashef

Thesis (M.Sc.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

SpdC protein was described as a novel virulence factor of S. aureus that affects biofilm formation, and pathogenesis and favors resistance to compounds targeting cell wall.We evaluated the possible association betweenspd C gene expression level and the virulence and or antibiotic resistance phenotypes in Staphylococcus aureus clinical isolates. The antimicrobial susceptibility of S. aureus clinical isolates (n=100) was determined by Kirby-Bauer disk diffusion method. Vancomycin susceptibility was determined by broth micro-dilution method.The level of the extracellular proteases and delta-hemolysin was evaluated by measuring the proteolytic and hemolytic zone diameters in skim milk and blood agar plates, respectively. Biofilm formation was assayed using 96-well microtiter plate method. Most (81%) of isolates were multidrug resistance and about half of the isolates (49%) were methicillin resistant S. aureus. Hemolysin and protease production were detectable in 79% and 71% of the isolates, respectively. All except four isolates were biofilm forming (96%). No significant correlation was detectable between the level of expression of spdCgene and the level of any virulence factor or the resistance phenotype to any antibioticusing Kendall{u2019}s Tau correlation coefficient and Wilcoxon rank sum test.The increased rates of antibiotic resistance together with the prevalence of virulent strains in hospitals is alarming and urges for an effective infection control strategy.The previously reported role of SpdC protein as virulence regulator in S. aureus clinical isolates needs further evaluation together with the determination of the predominant regulators for each virulence factor

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