Abstract
The present investigation was deliberately aimed at evaluating the biofilm-forming ability of 63 clinical MRSA isolates recovered from pharyngitis patients through different phenotypic assays. The molecular detection of adhesion (icaA/icaD/icaB/icaC), adhesins (fnbA/fnbB, clfA, and cna), staphylococcal accessory regulator (sarA), and α-toxin (hla) genes was done by employing polymerase chain reaction (PCR). Out of 63 isolates, 49 (77.8%) were found slime positive by the Congo red agar (CRA) method and 44 (69.8%) as biofilm positive by the quantitative microtitre plate assays. The results of MATH assay showed that most of the test pathogens are hydrophilic in nature. The molecular investigation of biofilm-associated genes revealed that 84.13% (n = 53) of isolates were found positive for icaADBC genes. The fnbA and fnbB genes were present in 49 (77.8%) and 51 (81%) MRSA isolates, respectively. In addition, 58.7% (n = 37), 73% (n = 46), and 69.8% (n = 44) of the isolates harboured the clfA, cna, and hla genes, respectively. Further, nearly 81% (n = 51) of the isolates were found positive for the gene sarA and all the ica negative isolates were also negative for the gene. Furthermore, the results of in vivo adherence assay unveiled the factual commonness in the in vitro adherence method.
Highlights
Myriad of bacterial pathogens inhabiting the environment cause several acute and chronic infections to human through their ability to form dynamic, structurally complex, and multilayered cellular matrix, termed as biofilms [1]
The qualitative slime production was assessed on the basis of the colour of S. aureus colonies developed on Congo red agar (CRA) plate according to the criteria described previously [16]
Though plethora of research findings have broadened our knowledge on the biofilm attributes of S. aureus, Methicillin-resistant Staphylococcus aureus (MRSA) emerging from various infection sites of human, it was necessarily important to widen our studies on the biofilm characterization of MRSA strains from new sites of infection as well
Summary
Myriad of bacterial pathogens inhabiting the environment cause several acute and chronic infections to human through their ability to form dynamic, structurally complex, and multilayered cellular matrix, termed as biofilms [1]. Though S. aureus can be isolated from various niches of human body, where it exists harmlessly as a commensal, it can be an opportunistic pathogen in causing diverse array of infections ranging from skin and soft tissue lesions to lethal infections such as osteomyelitis, endocarditis, pneumonia, and septicaemia [3] This commensal microflora readily colonizes the anterior nares and approximately 30% of healthy people carry this bacterium in their anterior nares [4]. As the nasal and extranasal colonization find chief prominence in the pathogenesis of invasive MRSA infections [5], studies on this pathogen from human throat (a least considered carriage site than the nares) are of dire need
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