Abstract
A total of 60 cotton swabs are collected from patients suffering from burn wound and surgical site infections admitted to Baghdad Teaching Hospital and Burn Specialist Hospital in Baghdad city during 9/2013 to 11/2013. All cotton swabs are cultured initially on blood agar and MacConkey agar and subjected for standard bacteriological procedures for bacteriological diagnosis. Twenty samples out of sixty are identified as Pseudomonas aeruginosa by conventional methods. The results of antibiotic susceptibility test illustrate that the antibiotics resistance rate of Pseudomonas aeruginosa isolates is as follows:100% (2020) for ceftriaxone, cefepime and carbencillin, 70% (14/20) for amikacin, 65%(13/20) for tobramycin, ceftazidim and gentamycin, 55% (11/20) for ciprofloxacin and norfloxacin, 50% (10/20) for piperacillin and impeneme, 30% (6/20) for aztreonam. All Pseudomonas aeruginosa isolates are investigated for detection of some virulence factors (haemolysin, protease, lipase enzymes, and extracellular pigments) and biofilm formation. The results of virulence factors reveal that all the isolates are haemolysin, protease, lipase enzymes and extracellular pigments producer, while 95% of the isolates are biofilm producer. Six isolates are selected to irradiation by using CO2 laser according to the results of antibiotic susceptibility and virulence factors at power densities (2000, 2500, and 3000) W/cm2 with exposure time (60 and 90) second. The results of CO2 laser irradiation illustrate that CO2 laser irradiation lead to a reduction in the mean value of the viable number CFU/ml of Pseudomonas aeruginosa isolates with the increase of the power density and exposure time. The results of the statistical analysis by using analysis of variance (ANOVA) one way and least significant differences-LSD show that there are statistical significant differences in the mean of the viable number CFU/ml between different power densities and different exposure times. After irradiation, antibiotic susceptibility and virulence factors tests of the irradiated strains are performed. The current study concludes that CO2 laser has bactericidal effect on P. aeruginosa isolates without any effect on its antibiotics susceptibility and virulence factors.
Highlights
A total of 60 cotton swabs are collected from patients suffering from burn wound and surgical site infections admitted to Baghdad Teaching Hospital and Burn Specialist Hospital in Baghdad city during 9/2013 to 11/2013
This result is in accordance with those gathered from other studies in Iraq as a study by [17] who finds that these percentages are 51.9 % and 40.4 % respectively, and [18] who finds that P. aeruginosa is the most common pathogen isolated from burn and wound infections with a percentage of 70% and 60% respectively
The result of this study reveals that the most common bacteria isolated from burn and wound infections is P. aeruginosa, this could be as a result of the fact that healthcare workers carry this microorganism in their wears and stand the chance of transmitting them to immune compromised burn wound patients
Summary
The cotton swabs are collected from burned wound and surgical site infections cultured on blood agar and MacConkey agar and subjected for standard bacteriological procedures including morphological, biochemical and API 20E diagnosis [12]. Detection of Some Virulence Factors: Detection of Haemolysin Production Blood agar plate is streaking with a single colony of an overnight growth from brain heart infusion agar and incubated at 37 °C for (18-24) hrs. Detection of Extracellular Pigments Production Pseudomonas agar medium is used to detect the bacterial isolates ability to produce the extracellular pigments pyocyanin and pyoveridin This medium is inoculated with a single colony of an overnight growth from brain heart infusion agar and incubated at 37°C for (18-24) hrs. Irradiation procedure Bacterial colonies are picked up from the brain heart infusion agar to a test tube containing 9 ml of normal saline mixed by vortex to get homogenous suspension compared with the McFarland solution (1.5×108 CFU/ml). The viable cells count CFU/ml is determined by using of the digital colony counter [16]
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