Genetic and Biofilm Characteristics of Staphylococcus aureus Isolates: A Study of the spa and mecA Genes | ||||
| Egyptian Journal of Medical Microbiology | ||||
| Volume 34, Issue 4, October 2025 | ||||
| Document Type: New and original researches in the field of Microbiology. | ||||
| DOI: 10.21608/ejmm.2025.377213.1576 | ||||
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| Authors | ||||
Hanaa M. Abd Al-Mogadami  1; Hadi R.R. Al-Taai2; Abbas A.F. Al-Dolaymi1
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| 1Biology Department, College of Education for Pure Science, Diyala University | ||||
| 2Biology Department, College of Science, Diyala University | ||||
| Abstract | ||||
| Background: Staphylococcus aureus is a Gram-positive, coccoid bacterium that plays a significant role in both community-acquired and hospital-acquired infections (CAIs and HAIs). It is non-motile, non-spore-forming, and facultatively anaerobic, which allows it to thrive in a variety of environments, including the skin, where it forms part of the normal Microbiota. Objective: This study aims to evaluate the ability of clinical Staphylococcus aureus isolates to produce biofilm, in addition to detecting the presence of the methicillin resistance gene mecA, and typing the spa gene to identify common genotypes. Methodology: Swabs were collected from 250 clinical samples, including specimens from burns, wounds, blood, urine, sputum, the nose, and the middle ear. A biochemical catalase test was performed by transferring a bacterial colony onto a glass slide and adding one drop of 3% hydrogen peroxide (H₂O₂). The tube coagulase test was done to detect the presence of the coagulase enzyme. Human plasma diluted (1:5) with steam-sterilized distilled water was mixed with an equal volume of bacterial culture in the nutrient broth. The spa-1113f/1514R primer set was used in PCR to detect the presence of the spa gene. Also, we used MecA-F/MecA-R to detect the presence of the mecA gene. The sterile microtiter plate method, containing 96 holes, was used to investigate the production of biofilm. Results: Twenty-nine isolates showed strong biofilm production (82.75%), while the intermediate and weak categories were 13.79% and 3.44%, respectively. Regarding the spa gene, three types were shown {t037, n=8 (67.68); t14870, n=2 (16.66); t044, n=2 (16.66)}. The results showed that 100% of the isolates tested positive for the gene, with a significant difference (P<0.05). PCR electrophoresis revealed the detection of the mecA gene, which encodes methicillin resistance. The results showed that 100% of the isolates tested positive for the gene, with a significant difference (P<0.05). Conclusion: The study showed a high prevalence of the mecA gene, responsible for methicillin resistance. Additionally, the study revealed a higher prevalence of the spa t037 strain compared to other strains. | ||||
| Keywords | ||||
| mecA; spa types; MRSA; Biofilm | ||||
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