Evaluation of exotoxin A gene and frequency of polymerase chain reaction sensitivity in detection of pseudomonas aeruginosa isolated from burn patients

Pseudomonas aeruginosa is a gram-negative pathogens opportunism which causes severe infections in human beings. The most common infection include: endocarditis، meningitis، septicemia and chronic lung infections in cystic fibrosis pa-tients. This bacterium has many pathogenic factors including; exotoxin A، lipopoly-sacharide، phospholipase C، pili، elastase and alkaline protease. The purpose of this study was to evaluate the frequency of exotoxin A gene (ETA) as a strong virulence factor and sensitivity determination of polymerase chain reaction (PCR) in pseudomonas aeruginosa isolated from second and third-degree burn patients. This study has performed in Besat University Hospital in Hamadan from January to December 2012. We used 170 isolated samples. The samples were isolated from blood and skin biopsy in second and third-degree burn patients. We had 79 strains positive culture of pseudomonas aeruginosa. Forward and reverse primers used for PCR were designed by DNASIS and Oligo software. Then genomic of known strains were extracted by DNA purification kit and indentified by PCR. The quality and quantity of the extracted DNA was determined using spectrophotometry. For determination of PCR sensitivity was used culture test as gold standard. DNA of pseudomonas aeruginosa (ATCC 27853) was used as a positive control. Finally data was analyzed using SPSS software. Out of 170 isolated samples، 79 strains of pseudomonas aeruginosa isolated from burn patients had positive culture. PCR of isolated positive culture demonstrated that 5 strains (6. 33%) were with out this virulence factor and 74 strains (93. 67%) had ETA gene. So the sensitivity of test based on sensitivity formula was 94. 04%. Our results showed that sensitivity of PCR mediated ETA gene in detection of pseudomonas aeruginosa strains is considerable and this factor can be used as a good factor identifying of pseudomonas aeruginosa. It seems more studies with larger sample size is necessary in this area.