Khosravi Azar Dokht, Shafie Fatemeh, Abbasi Montazeri Effat, Rostami Soodabeh
Dept. of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; Health Research Institute, Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
Dept. of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
Burns. 2016 Aug;42(5):1116-1120. doi: 10.1016/j.burns.2016.02.012. Epub 2016 Jun 2.
Pseudomonas aeruginosa infections have emerged as a major infectious disease threat in recent decades with infection particularly in immunocompromised hosts. P. aeruginosa possesses several virulence factors with involvement in pathogenesis. The aim of this study was to examine the prevalence of virulence genes of toxA and toxS and to analyze their relation to antimicrobial resistance of the isolates.
In total 185 clinical isolates of P. aeruginosa were collected from burn patients. Antimicrobial susceptibility testing was done by disk diffusion method. PCR amplification was performed on extracted DNA from the isolates and the presence of encoding genes for exotoxin A (toxA) and exoenzyme S (toxS) were investigated by using specific primers.
In disk diffusion method, the isolates showed high sensitivity to colistin sulfate (100%) followed by imipenem (41.9%). The most prevalent resistance was seen against ceftazidime (90.5%) and gentamicin (88.5%). Multidrug resistance (MDR) demonstrated in 113 isolates (76.35%). According to PCR amplification, 133 (89.8%) and 127 (85.8%) isolates possessed toxA and toxS genes respectively. The frequencies of genes among MDR strains were 102 (76.6%) for toxA and 98 (77.1%) for toxS. Eighty five MDR isolates possessed both genes (73.9%). The non-MDR strains (23.65%), harbored lower prevalence of simultaneous toxA and toxS genes (26%) compared to MDR strains.
The present study established a higher frequency of MDR among P. aeruginosa isolates from burn patients. It was found that the frequency of both toxA &S genes were significantly higher in MDR strains P. aeruginosa strains.
近几十年来，铜绿假单胞菌感染已成为主要的传染病威胁，尤其是在免疫功能低下的宿主中发生感染。铜绿假单胞菌具有多种参与致病过程的毒力因子。本研究的目的是检测toxA和toxS毒力基因的流行情况，并分析它们与分离株抗菌药物耐药性的关系。
从烧伤患者中总共收集了185株铜绿假单胞菌临床分离株。采用纸片扩散法进行抗菌药物敏感性试验。对分离株提取的DNA进行PCR扩增，使用特异性引物研究外毒素A（toxA）和外酶S（toxS）编码基因的存在情况。
在纸片扩散法中，分离株对硫酸多粘菌素显示出高敏感性（100%），其次是亚胺培南（41.9%）。对头孢他啶（90.5%）和庆大霉素（88.5%）的耐药最为普遍。113株分离株（76.35%）表现出多重耐药（MDR）。根据PCR扩增，分别有133株（89.8%）和127株（85.8%）分离株携带toxA和toxS基因。MDR菌株中toxA基因的频率为102株（76.6%），toxS基因的频率为98株（77.1%）。85株MDR分离株同时携带这两个基因（73.9%）。与MDR菌株相比，非MDR菌株（23.65%）同时携带toxA和toxS基因的流行率较低（26%）。
本研究证实烧伤患者分离的铜绿假单胞菌中MDR的发生率较高。发现MDR铜绿假单胞菌菌株中toxA和toxS基因的频率均显著更高。
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