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دراسة بكتريولوجية وجزيئية للجين norA في بكتريا Staphylococcus species المقاومة للمثيسيلين == Bacteriological and molecular study of norA gene in Methicillin Resistant Staphylococcus species bacteria
Author name:
احلام خليفة عبد الله التميمي
Supervisor name:
محمد فرج شذر المرجاني
General topic:
Biology
Specific topic:
Microbiology - Bacteria
Degree:
Master
University:
Mustansiriyah University - College Of Science
Language:
English
University location:
Baghdad
First pages:
24T3180 - p.pdf
Abstract:
One hundred clinical isolates of methecillin resistant Staphylococcus spp. were collected from different sources including : (80,10,5,3,2) isolates from wounds, blood, urine, pus, otitis media respectively from different hospitals in Baghdad during the period from 1/9/2013to 1/1/2014. All isolates were identified through morphological, cultural and some biochemical testes. Coagulase test was performed done by using both tube and slide method The results showed that 75% of isolated were positive for this test which refer to Staphylococcus aureus, and 25% were Coagulase negative Staphylococci (CoNS) .The antibiotic susceptibility test against 10 antimicrobials were determined by the agar diffusion method ; Results showed that all isolates were resistant to ceftriaxone, cloxacillin and aztreonam. The most effective antibiotic aganist isolates were ciprofloxacin and norfloxacin. The Minimum inhibitory concentrations (MICs) for ciprofloxacin and norfloxacin were determined by agar dilution method .The MIC isolates ranged from 4 to 1024 μg/ml for both antibiotics. On the other hand the minimum inhibitory concentrations (MICs) were determined for quartenary ammonium compounds and chloroxylenole . Results revealed that MIC for chloroxylenole were 50 - 500μg/ml and 500μg/ml for quartenary ammonium compounds.Thirty Four of methicillin resistant isolates were choosen for detect efflux pumps by using Ethidium Bromide - Agar Cartweel Methode (EtBrCW), which include ethidium bromide dye as marker to detect efflux pumps, the result showed that 18 isolates(52.9%) give positive result, 3 isolates (8.82%) were intermediate, wherase remaining isolates 13 isolates(38.29%) were give negative result.Polymerase Chain Reaction (PCR) technique was performed done using specific primer targeting the specific sequences of the norA gene, The results showed that norA found in 16 isolates (47%). Nucleotide sequence for norA gene in 9 isolates were determined ,results revealed consistency reaching up to 90 % as compared nitrogen bases sequence of the norA gene present in the Staphylococcus aureus strain in NCBI Detection of gene expression was performed done by using q RT - PCR technique after RNA extraction and cDNA syenthesis , the result showed that gene expression were various among isolates , and the gene expression increase with increasing MIC of ciprofloxacin and norfloxacin.The effect of biosurfactant as efflux inhibitors was tested by detection of MIC for ciprofloxacin alone and mixed with biosurfactant , the result showed ability of biosurfactant in decreasing the MIC to two or four - fold in the presence of inhibitor this refer to biosurfactant effective material against NorA efflux pump.
