Identification of S.aureus by specific 16S rRNA and detection of mec A gene from clinical samples in patients of Basrah governorate in Iraq.

Staphylococcus aureus is a serious human pathogen that causes vast range of contagious conditions both in hospitals and community settings. Methicillin resistant S.aureus (MRSA) are oftenly multidrug resistant in hospital and community that resulted in significant mortality and morbidity. Today, the methicillin resistant S.aureus (MRSA) had become endemic in a hospitals worldwide. So, the need to quick diagnosis and identify of (MRSA) by using PCR technique. A total of 150 clinical specimens include: wound swabs, sputum, throat swabs, nasal swabs, pus and urine, that collected randomly from patients suffering of UTI, wound infection and upper respiratory tract infection, who attended the outpatients and inpatients Clinics of Alsadr Teaching Hospital and Al-Shefa General Hospital in Basrah City south of Iraq country. The identification of the methicillin resistant S.aureus (MRSA) from clinical specimens were performed depending on morphological and biochemical assay based positive cultures of S.aureus from clinical samples. Out of 150 clinical specimens, 61(40.66%) of Staphylococcus aureus were isolated and identified by conventional methods, 20 (62.5%) of these bacterial isolates were from ear pus samples followed by 18 (60.0%) were from sputum, 11 (26.82%) were from urine, 6 (28.57%) were from nasal, 4 (21.05%) were from throat and 2 (28.57%) were from wound samples respectively. Also, 56 (37.33%) of (CONS) were detected from clinical samples and they included Staphylococcus epidermidis which was frequently isolated bacterial species 41 (73.21%) followed by 15 (26.78%) of Staphylococcus saprophyticus. All isolates of S.aureus were be examined for methicillin resistance by disc diffusion assay of oxacillin and cefoxitin antibiotics and by using modified Kirby-Bauer method. Inhibition zones according to the Clinical and Laboratory Standards Institue (CLSI, 2021) which recorded a higher resistance (100%) to both antibiotics. PCR based molecular method was used for accurate identification of specific 16S rRNA gene and mec A gene in S.aureus (MRSA) isolates from clinical samples. The results of PCR amplification of 16srRNA specific gene from S.aureus isolates revealed that 52/61 isolates from a total 61 of S.aureus that detected in clinical samples through conventional methods with percentage of (85.24%) had a clear bands of approximately 228 bp which corresponds to identification of S.aureus strains. While, the PCR amplification of 42/52 isolates with percentage of (80.76%) were generated a clear bands of approximately 310 bp which corresponding to detect mec A gene in methicillin resistant strains of S.aureus isolates.