Screening of genes encoding adhesion factors and biofilm production in methicillin resistant strains of Staphylococcus aureus isolated from Palestinian patients

Abstract

Background Intercellular adhesion and biofilm production by Staphylococcus aureus makes these bacteria resistant to antimicrobial therapy. Here, Methicillin-resistant Staphylococcus aureus (MRSA) strains were characterized and the prevalence of genes encoding adhesion factors and biofilm formation was determined. Results All 248 MRSA isolates identified by cefoxitin disc diffusion were positive for the mec A gene. SCC mec -IV was the most frequently detected genotype (92.7%) and SCC mec -IVa was also very prevalent (84.3%). The quantitative microtiter plate assay showed that all the isolates were able to produce biofilm with levels ranging from high (21%) to moderate (46.4%) to low (32.7%). All the strains possessed the icaD/icaA genes and produced biofilm ( P < 0.05). None of the isolates possessed the bap gene . Furthermore, 94.8% of the isolates were positive for eno, 80.2% for clfA and for clfB , 78.2% for fnbA , 76.2% for ebps , 62.2% for fib , 39.9% for cna and 29.0% for fnbB. Also, nearly 69.8% of the isolates were positive for the gene sarA . All four agr groups were present: agr group 1 was predominant with 39.5%; agr group 3. agr group 2 and 3 strains carried more toxin-producing genes, and frequently produced more toxin. Sixty-six (26.6%) of the strains were multidrug resistant. All were vancomycin sensitive. Agr group I is more resistant to ciprofloxacin and gentamicin while agr group III is more resistant to erythromycin. Maximum sensitivity was to gentamicin and SXT, and they could be considered drugs of choice for controlling MRSA mediated infections in this region. Conclusions Biofilm development in MRSA might be an ica dependent and one needs to investigate the involvement of other global regulators, agr and sarA , and their contribution to the biofilm phenotype, as the high rate of biofilm production among the studied strains of S. aureus .

Phenotypic and Molecular Detection of Biofilm Formation in Staphylococcus aureus Isolated from Different Sources in Algeria

“…The biofilm-producing S. aureus strains isolated from food in this study carried agrI, II, or III, while other studies found that the majority (60%) of biofilm-producing S. aureus were the carriers of agrIII [6]. In S. aureus isolated from humans in this study, the agrI was more predominant in biofilm producers followed by agrII, which disagreed with a previous study in Palestine that reported biofilm-producing S. aureus isolated from humans mainly possessed agrI and agrIII [50]. It was reported that agr expression can restrict biofilm formation allowing the colonization of a new surface by dispersion of the bacterium from a previously formed biofilm [12,61].…”

“…Here, the fnbB gene was rarely detected among non-biofilm-producing isolates but found in all biofilm-producing isolates from food matrices and humans. These findings were in discordance with a previous reports where either the fnbB gene was not detected in biofilm-producing isolates [6] or detected in a low level (29.0%) in MRSA isolated from humans [50]. However, a previous study reported that fnbB occurred frequently (99.5%) in S. aureus isolated from humans [46].…”

“…Clumping factors ClfA and ClfB encoded by the genes clf A and clf B are the most important proteins for the binding of S. aureus to fibrinogen and fibrin [56]. In this study, all S. aureus harbored clf AB genes, which is contradictory to reports on sheep mastitis isolates [7] and isolates from human nasal and clinical samples [50].…”

“…In this study, presence of the bap gene was not found in any of the isolates. In general, the bap gene, which promotes inert surfaces and intracellular adhesion, is rarely observed in S. aureus [39,50] and its presence has only been reported in few S. aureus isolates from cases of bovine and sheep mastitis [39,51,52].…”

Antivirulence properties and related mechanisms of spice essential oils: A comprehensive review

“…Some S. aureus is ica‐independent, in which the biofilm‐associated protein (Bap) is important for bacterial accumulation (Yadav et al., 2015). In addition, the biofilm of Staphylococcus is under the control of several genetic loci, namely, sarA (staphylococcal accessory regulator), luxS , and agr QS systems (Azmi, Qrei, & Abdeen, 2019). Several spice essential oils and their components have been revealed to show inhibitory effects on the production of EPS or the in‐depth regulatory genes.…”