Molecular diagnoses of the resistance of genes in Staphylococcus aureus to antibiotics in the diabetic foot infections

Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen in Iraq and is emerging in the community and hospital. A total of 132 specimens were processed over a period of four months (1 January 2022-30 April 2022). S. aureus was identified using traditional biochemical tests and confirmed by the detected coagulase gene. MRSA isolates were characterized by seven conventional phenotypic methods using the methicillin resistance gene (mecA) detection test as a reference standard. Six phenotypic methods were used to identify β-lactamase production. The isolated MRSA were subjected to antibiotic susceptibility tests by seven methods. The MRSA isolates were subjected to staphylococcal chromosome cassette methicillin-resistance (SCCmec), by multiplex polymerase chain reaction (PCR). The presence of Panton-Valentine leucocidin (pvl) and toxic shock syndrome toxin (tst) genes was tested by monoplex PCR. The overall isolation rate of S. aureus was 17 (12.87%) isolates among various specimens. The mecA was recognized in 4 (23.52%) isolates (MRSA). Phenotypic methods including cefoxitin disc diffusion, chromogenic assay was highly effective for detecting MRSA. Biofilm forming by both MRSA strains indicates the high ability of these strains to persist in hospital environments which increases the risk of disease development in hospitalized patients. Additionally, resistance to antimicrobials in biofilm-forming isolates contribute to bacterial persistence which may lead to chronic infections and treatment problems.