Molecular mapping of biofilm related genes and accessory gene regulator agr typing in Staphylococcus aureus

Abstract

Internalization of S. aureus is strain-dependent and internalized bacteria have been reported to newlineover express adherence and biofilm-forming genes in comparison to those that remain in the newlinesupernatant particularly by expressing various biofilm producing genes. Strains yielding highest newlineinvasion percentages are mostly carry icaA, icaD, bap, can, fnbA and clfA genes irrespectively of the newlinepresence of other resistance genes. Further, Biofilm-embedded bacteria that gain resistance to immune newlinedefense and antibiotics by antibiotic degrading enzymes, efflux pumps, and certain gene products of newlinewhich expression are changed by the quorum sensing cause chronic and recurrent infections such as newlineindwelling device associated infections. Moreover, most of the S. aureus strains of animal origin, newlinereported from all over the world are multidrug-resistant and carry multiple virulence genes, posing a newlinepotential public-health risk. Therefore the present study was undertaken a) to determine ability of S. newlineaureus to produce biofilm; b) to map the presence of biofilm related gene in biofilm forming S. aureus newlinec) to determine accessory gene regulator (agr) typing in biofilm forming S. aureus. Out of 175 (100 newlinehuman and 75 animals) samples, 86 (46 human and 40 animal) isolates were confirmed based on newlinecultural, morphological, biochemical tests and by confirming the presence of species specific nuc newlinegenes. The overall prevalence of S. aureus was 49.14% (61.3% and 40.0% in human and animal). The newlineconfirmation of methicillin resistance mecA gene revealed its presence in 32 isolates (12 human and 20 newlineanimals) with 18.28% (16.0% and 20% in human and animal ) overall prevalence of MRSA was in all newlinethe isolates. Congo red agar (CRA) method revealed 47 (23 human and 24 animal) biofilm producer newlineisolates in 86 isolates with 54.65% (48.9% and 51.06% in human and animal) overall prevalence of newlinebiofilm producing S. aureus. The amplification of icaA, icaD, bap, can, fnbA and clfA biofilm forming newlinegenes showed highest presence of IcaD gene (41) followed by clfaA (26), fnbA (24), can (18) and bap newline(8). None of isolate revealed the presence of icaA gene. The overall prevalence of icaD, fnbA, clfA, bap newlineand can was 47.67%, 27.91%, 30.23%, 9.30% and 20.93% respectively. The agr typing has been newlinerecommended as an important tool for deciphering of important epidemiological information about S. newlineaureus in clinical isolates. The global presence of these genes makes them an effective tool for the newlineepidemiological studies, and also for investigating the genetic relatedness and heterogeneity of S. newlineaureus. A majority of isolates belonged to agr Group II (51.16%), followed by agr Group I (32.55%) newlineand agr Group III (16.27%). The agr typing of 86 isolates revealed 28 isolates of agr type I (15 human newlineand 13 animal), 44 isolates of agr type II (24 human and 20 animal) and 14 isolates of agr type III (7 newlinehuman and 7 animal). None of the isolates was positive for agr type IV. 13 human isolates and 5 newlineanimal isolates revealed the amplification of more than one type of agr genes. However, 8 human and newline12 animal isolates revealed no amplification of agr genes. The findings of study suggest that MRSA newlineare adopting the environment and using multiple approaches to develop resistance. A single mechanism newlineis not responsible for the methicillin resistance in S. aureus. S. aureus is very smartly using different newlinemechanism to develop resistance. Thus, continuous monitoring is required to overcome the drug newlineresistance in MRSA. The presence of multiple agr typed need further studies are required to establish newlinethese parentage and to link them with other MRSA. newline newline