دراسة تاثير ضوء الليزر الثنائي الصمام (632 نانومتر) على بكتريا المكورات العنقودية الذهبية بوجـود المثلين الازرق كمتحسس ضوئي == Study of Photodynamic Effect of (632 nm) Laser Diode Light On Staphylococcus Aureus Using Methylene Blue As A Photosensitizer
Author name:
ضياء خليل اسماعيل
Supervisor name:
نورية عبد الحسين علي
General topic:
Biology
Specific topic:
Biotechnologies
Degree:
Master
University:
University of Baghdad
Language:
English
University location:
Baghdad
First pages:
24T2657 - p.pdf
Abstract:
شملت الدراسة ثمان وسبعين عزلة من بكتريا المكورات العنقودية الذهبية عزلت من مئة وعشرين عينة تم الحصول عليها من عينات حروق وجروح قيحية وتجرثم الدم ومن مرضى يعانون من التهابات المجاري البولية, ومن اكثر من مستشفى للفترة من تشرين الثاني / لغاية اذار/ 2014.تم | Seventy eight isolates of S. aureus bacteria were obtained from one hundred and twenty samples which were collected from different body sites and lesions (urine, blood and purulent wounds and burns) of patients from both sexes during the period November - 2013 to March - 2014. Methicilline sensitivity test (5µg MET disc) showed the appearance of methicillin - resistant in thirty seven Staphylococcus aureus isolates. Following exposure to laser light with a wavelength of 632 nanometer in the presence of Methylene blue at a concentration of 300µM at various exposure times (2, 4, 6, 8, 10, 12 and 15min), the results showed that the maximum decrease in viable colony counts ranging approximately from (6.9 to 3.8) log10 CFU /ml. Highly significant reduction in the viable count was achieved at 10, 12, 15 min exposure times, and 99% killing of cells were obtained when Photosensitisation of S. aureus using diode laser light at an energy density at 458.6 watt/cm2 for 15 mints. While in their exposure to the laser light in the absence of the dye or the dye in the absence of the laser light presented no significant effect on the viability of the S. aureus isolates. Both of phenotypic and genotypic investigation of the changes in virulence factors and the antibiotic - resistance were evaluated before and after irradiation with laser light.Results of photosensitization susceptibility tests showed large variations in the susceptibility, the isolates with resistant to methicillin before laser irradiation, become sensitive to it with percentage of 21.6%; in contrast the isolates with sensitive to vancomycine become resistant to it with percentage of 32.43%.On the other hand, the isolates that were resistant to Cefotaxime before laser irradiation become within the sensitivity range after laser irradiation with percentage of 51.35%, and also there were isolates within the sensitivity range before laser, become sensitive to Ciprofloxacin with percentage of 27.02% after irradiation. And the isolates of the S. aureus with resistant to Norfloxacin before laser irradiation, become sensitive to it with percentage of 16.2%. Also resulted in decrease the activity of ? - haemolysis, with 33 (90.3%) isolates of S. aureus in comparison to control as shown in blood agar method assay. In contrast had no effect on thermonuclease enzyme after irradiation.Detection of three genes represented in MRSA isolates by a confirmatory test was carried out using Polymerase chain reaction (PCR) technique. The results of the PCR amplification of mecA gene noted that it was present in 27 (72.2%) S. aureus isolates, While hlb gene detected 17(46%) isolates of 37 samples of S. aureus isolates, 14 of 17 hlb - positive S. aureus isolates(82.3%) were showed reduction in toxin production after exposure to laser light, whereas no altered or deficiency in thermonuclease gene (nuc).
