Estimation of Biofilm Components and Prevalence of SDR Genes among Staphylococcus Aureus Isolated from Anbar Hospitals

Background Nosocomial infections, a major health problem, are due at 80% to biofilm‐associated infection. Staphylococcus aureus , a prominent biofilm producer, has both MRSA and MSSA biofilm-forming capabilities that highlight its persistence in hospital environments. In previous studies, less focus was given to the components of the biofilms. Therefore, understanding biofilm composition has become crucial. Objective In this study, the components in the biofilm matrix in MRSA and MSSA isolates were estimated, and the prevalence of sdr genes ( sdrC,sdrD,sdrE ) among S. aureus strains was investigated. Methods Between September, 2023 and January, 2024, a total of 200 specimens were collected from patients with suspected Staphylococcus aureus infections. Eighty-two isolates were identified as S. aureus from various sources, including wounds, nasal swabs, ear swabs, and blood, based on macroscopic, microscopic, and molecular properties. Biofilms were subjected to DNase and proteinase K treatment in order to identify their biochemical composition. Multiplex PCR was used to determine the distribution of sdr genes among isolates. Results The average reduction after treatment with proteinase K in MSSA biofilms (29.67±16.62) was significantly lower than in MRSA biofilms (46.21±26.33, p =0.032). Also, when treated with DNase, MRSA biofilms showed a greater average reduction (49.65±25.30) compared to MSSA biofilms (28.71±20.98, p =0.006). MRSA and MSSA biofilms also had different polysaccharide concentrations, with MSSA biofilms having significantly higher levels (206.86±82.92 μM/OD595) than MRSA biofilms (85.80±32.52 μM/OD595, p =0.005). The sdrC gene was most common in the gene profiles of MRSA (100%) and MSSA (50%). There was a strong association between the presence of the sdrD gene and methicillin-resistant S. aureus isolates ( p < 0.001). Conclusion These findings indicate that the biofilms of MRSA isolates are largely composed of proteins and eDNA, while MSSA isolates rely on polysaccharides in their biofilms. The results indicate the importance of proteins encoded by SDR genes in the development of biofilm structure.