Adhesins Encoding Genes and Biofilm formation as Virulence Determinants in Methicillin Resistant Staphylococcus aureus Causing Hospital Acquired Infections

Background: Methicillin resistant Staphylococcus aureus (MRSA) is a major infection-causing pathogen in health care settings. Adhesins, which are part of the class of molecules known as microbial surface components recognizing adhesive matrix molecules (MSCRAMMs), and the development of biofilms are crucial elements in the colonization and antibacterial resistance of this organism. Objectives determines the prevalence of adhesins genetic determinants and biofilm formation among MRSA isolates in patients with hospital acquired infections (HAIs) at Mansoura University Hospitals (MUHs), as well as staphylococcal cassette chromosome mec (SCCmec) typing. Methodology: From patients with HAIs in MUH Departments, clinical samples were collected. Routine microbiological methods, cefoxitin sensitivity tests, and PCR for the mecA gene were used to identify MRSA isolates. The MRSA isolates' ability to form biofilms was evaluated using a microtitre plate assay. Multiplex PCR was used for SCCmec typing and screening for the genes ica D, eno, ebps, cna, fnbA, fnbB, fib, clfA and clfB. Eighty-five MRSA isolates were identified. Results: Type III of SCCmec MRSA was the most frequent (63.5 %). In 65 isolates (76.5 %), biofilm production was detected. Strong biofilm-forming isolates were the most prevalent; accounting for 49.4% of all MRSA isolates. The eno gene was the most common MSCRAMMs gene (95.3%), whereas clfB was the least (29.4%). The icaD gene was present in 90.6% of MRSA isolates and in all biofilm forming isolates. The icaD and the development of biofilms were significantly associated (P = 0.0001). None of the MSCRAMMs genes evaluated were significantly associated with biofilm development. The highest gene association was icaD with eno gene; 85.9%. The highest 3 MSCRAMMs genes co-existance was eno, ebps, and fnbA; 64.7%. Conclusion: The increased frequency of biofilm formers among infecting MRSA isolates revealed that biofilm formation may account for isolates persistence in hospital setting and hence transmission to patients. The prevalent existence of icaD and eno among biofilm formers indicates the possible molecular relationship that may link these genes and infection with biofilm forming MRSA which need further investigations.