الكشف الجزيئي لبعض عوامل الضراوة في بكتريا Staphylococcus aureus المقاومة للمثيسيلين المعزولة من مصادر سريرية مختلفة

Molecular detection of some virulence factor in methicillin resistant Staphylococcus aureus isolated from different clinical sources

This study included obtaining 31 isolates of Staphylococcus aureus from patients attending the Obstetrics and Gynecology Teaching Hospital, Imam Hussein Medical City, and the Public Health Laboratory, as well as outpatient clinics, and from various clinical sources represented by burns, wounds, blood, urine, and skin. These isolates were subjected to some microscopic, biochemical and molecular examinations to ensure their classification in terms of genus and species. These isolates were also subjected to a test to identify methicillin-resistant bacteria from those sensitive to them. This was followed by an investigation of the ability of methicillin-resistant isolates to produce some virulence factors represented in the biofilm, protease and hemolytic enzyme, as well as the investigation of the presence of some virulence and antibiotic resistance genes, including mecA, hlb, lukED and tetK. The results showed the following:
 The morphological and biochemical tests proved that the obtained isolates belonged to the genus Staphylococcus, with 31 isolates out of 150 samples, with an isolation rate of 20.6%, which included ten isolates from burns, eight isolates from wounds, three from blood, and five isolates from urine and skin, with percentages (32.25, 25.80, 9.67, 16.12, 16.12)%, respectively.
 The number of bacterial isolates resistant to methicillin was 24, with a rate of 77.41%.

 By testing the sensitivity of methicillin-resistant Staphylococcus aureus isolates to antibiotics, it was found that all isolates are resistant to (Benzyl Penicillins, Amoxicillin, Piperacillin, Ampicillin – Sulbactam, Amoxicillin Clavulanic Acid, Carbenicillin, and Amoxicillin) by 100%, and the same percentage for the group of antibiotics belonging to the Cephalosporins family represented by in Cefadroxil, Cephalexin of the first generation, Cefuroxime of the second generation, Cefixime, Cefpodoxime, Ceftriaxone, Cefotaxime, Ceftizoxime, Ceftazidime, Cefoperazone of the third generation, Cefepime, and Cefpirome of the fourth generation. These bacteria showed 100% sensitivity to (Vancomycin and Linezolid).
 The results of the molecular tests showed the presence of genes (femA, mecA, hlb and tetK) by 100% in the twenty-four tested isolates, while the lukED gene was present by 58.3%.
 Studies have shown that all isolates have the ability to produce biofilm using the qualitative method, and their ability was distributed between the strong producers by 29.16%, the medium producers by 50%, and the weak by 20.8%, while the isolates were distributed when using the quantitative method represented by the plate method, with 25% of them being highly productive and 66.6% of them are medium and 8.3% of them are of poor production.
 It was found that there is a relationship between the strength of the biofilm and the resistance of bacteria to antibiotics.

 The results showed that the isolates that have the ability to produce the protease enzyme are 20 isolate, with a rate of 83.3%, using casein as a base material, and the isolate S9 produced the highest production with an enzyme activity of 13.9 units / ml.
 The isolates (S6, S9, and S22) showed low activity