Abstract
Total of 120 samples were collected from different body sites and lesions for patients from bothsexes. There were 78 isolates (65%) Staphylococcus aureus from them 37 isolates were Methicillinresistant Staphylococcus aureus (MRSA). Each isolate was exposed to diode laser 632nmwavelength with 300µM of methylene blue (MB) at 458.6 watt/cm2for 15 minutes, bothphenotypic and genotypic changes in virulence factors and the antibiotic-resistance wereevaluated before and after irradiation with laser light. It was observed that the effect of sub-lethaldose on the antibiotic sensitivity was isolate-dependent. In general, results showed large variationsin the susceptibility of antibiotic. Exposure to diode laser increased resistance to Vancomycin, incontrast increased sensitivity to Methicillin, Ciprofloxacin, and Norfloxacin. Also Results showeddecreases the activity of β-haemolysin, with 33 (90.3%) isolates of S. aureus in comparison to thecontrol as shown in blood agar method and haemolytic titration assay, but there was no effect onthermonuclease enzyme after irradiation. Detection of three genes represented in MRSA isolatesby a confirmatory test was carried out using PCR technique. The results of the PCR amplificationof mecA gene noted that it was present in 27(72.2%) S.aureus isolates and 14(83.3%) isolatesshowed reduction in β-toxin production after exposure to laser light, with no altered or deficiencyin thermonuclease gene (nuc).
Highlights
Total of 120 samples were collected from different body sites and lesions for patients from both sexes
The results of effect of the exposure to laser light on antibiotics sensitivity of 37 isolates of S. aureus (MRSA) were including in table (2) which showed that the isolates resistant to methicillin before laser irradiationexposure, become sensitive to it with percentage of 21.6%, in contrast the isolates that sensitive to Vancomycin become resistant to it with percentage of 32.43%
The isolates that were resistant to Cefotaxime before laser irradiation become within the sensitivity range after laser irradiation with percentage of 51.35%, and there was isolates within the sensitivity range of Ciprofloxacin before laser, become more sensitive after irradiation, and the isolates of the S. aureus that resistance to Norfloxacin before laser irradiation, become sensitive to it with percentage of 16.2%
Summary
Total of 120 samples were collected from different body sites and lesions for patients from both sexes. Results showed decreases the activity of β-haemolysin, with 33 (90.3%) isolates of S. aureus in comparison to the control as shown in blood agar method and haemolytic titration assay, but there was no effect on thermonuclease enzyme after irradiation. The quickly growing resistance of Methicillin resistant Staphylococcus aureus (MRSA) to conventional antimicrobial agents and the limitation of antibiotic treatment for these diseases is that even after successful killing of the infecting organism, secreted virulence factors may still be present and cause significant damage to host tissues [1]. The main objective of this study is to assess the effects of diode laser on Staphylococcus aureus (MRSA); their resistance pattern, its virulence factors, its genes content, viability of S. aureus to the local therapeutic agents with presence of methylene blue.
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