الفهرس | Only 14 pages are availabe for public view |
Abstract The importance of studying S. aureus microbes was attributed to the opportunistic nature of this bacterium, it also represent one of the most dangerous bacteria that causes nosocomial infection, as well as the high capability of this microorganism to acquire resistance against the different classes of antimicrobial chemotherapeutic agents and disinfectants. The current study was carried out to investigate MRSA phenotypically and genotypically, detect the antimicrobial resistance in local MRSA isolates to different classes of antimicrobial chemotherapeutic agents and disinfectants and to detect types of integrons in these MDR isolates. Two hundred specimens were collected from patients with various clinical cases including burn, sputum, blood, peritoneal fluid, urine, ear discharge of otitis media and diabetic foot lesions from Zagazig University Hospitals and burn unit of El-Ahrar Educational Hospital in Sharkia, Zagazig, Egypt. In addition to collection of 8 environmental isolates from the medium from which samples were collected. The specimens were processed and yielded 117 non duplicate isolates that were identified as S. aureus based mainly on Gram staining, colony morphology on nutrient agar medium, fermentation on mannitol salt agar medium, β- hemolysis on blood agar and being catalase and coagulase positive. The susceptibility of S. aureus clinical and environmental isolates to different members of antistaphylococcal drugs were determined by agar disk diffusion method. The isolates showed high sensitivity to vancomycin (100%), linezolid (98.3%) and sulfamethoxazole- trimethoprim (90.59%). Meanwhile, these isolatesshowed high resistance to methicillin (100%), cefotaxime (76.07%) and cefotriaxone (71.8%). Out of 117 clinical and 8 environmental isolates, 72 and 6 were classified as MDR, respectively, being resistant to 3 groups or more of antimicrobial chemotherapeutic agents. The susceptibility of MDR isolates to 7 selected groups of disinfectants and antiseptics was tested by determination of the MIC by agar dilution method. The MDR isolates showed high sensitivity to gluatraldhyde, cetrimide, chlorocresol and chlorhexidine. However the same isolates showed low sensitivity to hydrogen peroxide, povidone iodine and ethanol. The MIC for gluatraldhyde ranged between 0.3 mg/ml and 1.6 mg/ml. The MIC for cetrimide ranged between 0.002 mg/ml and 0.01 mg/ml. The MIC for chlorocresol ranged between 0.1 mg/ml and 0.5 mg/ml. The MIC for each of chlorhexidine (0.02 mg/ml and 0.06 mg/ml), hydrogen peroxide ( 0.03 mg/ml and 0.1 mg/ml) , ethanol ( 80 mg/ml and 200 mg/ml) and for povidone iodine (2 mg/ml and 10 mg/ml). The MDR of S. aureus clinical and environmental isolates were screened for the prescence of two classes of integrons , and the prescence of qacE gene by PCR technology. The study showed that Integron І was the most predominant among the MDR–MRSA isolates. It was detected using PCR technology and found in 48 (66.67%) of total 72 cllinical isolates; include 14 in gDNA and 34 in plasmid DNA. It was detected by PCR technology and gel electrophoresis at bands matched to 932 bp. Meanwhile, integron Ι was not detected in any of the environmental isolates. |