Hemati Saeed, Azizi-Jalilian Farid, Pakzad Iraj, Taherikalani Morovat, Maleki Abbas, Karimi Sajedeh, Monjezei Azam, Mahdavi Zahra, Fadavi Mohamad Reza, Sayehmiri Kourosh, Sadeghifard Nourkhoda
Clinical Microbiology Research Center, Department of Microbiology, Faculty of Medicine, Ilam University of Medical Sciences, Ilam, IR Iran.
Prevention of Psychosocial Injuries, Research Centre, Ilam, IR Iran.
Iran J Microbiol. 2014 Jun;6(3):133-9.
Pseudomonas aeruginosa is a Gram-negative bacterium that considered as important opportunistic human pathogen. One of the mechanisms that help bacteria to tolerate survival in adverse conditions and resistance to antibiotics is biofilm formation through quorum sensing (QS) signals and toxin-antitoxin (TA) systems. QS and TA are two systems that have important roles in biofilm formation. QS is a global regulatory mechanism that enable bacteria to communicate with each other by production of auto inducers (AI) molecules in population. Because of importance biofilm formation in P. aeruginosa infections, here, we studied frequency of QS and TA genes among clinical isolates of P. aeruginosa with ability of biofilm formation.
One hundred and forty clinical isolates of P. aeruginosa were collected from Tehran and Ilam hospitals. The isolates were identified by biochemical tests. Biofilm formation was evaluated by microplate method. After DNA extraction by boiling method, the frequency of QS genes (lasIR, rhlIR), and TA genes (mazEF, relBE, hipBA, ccdAB and mqsR) were analyzed by PCR.
Our results showed that maximum resistance is related to aztreonam (72.85%) antibiotic. Most of isolates were able to produce biofilm (87.15%) and the majority of them formed strong biofilm (56.42%). PCR results showed that frequency of mazEF, relBE, hipBA, ccdAB, mqsR, lasIR and rhlIR genes were 85.71, 100, 1.42, 100, 57.14, 93.57 and 83.57 percent, respectively.
Clinical isolates of P. aeruginosa had high ability to form biofilm, and QS and TA system genes among these isolates were very high (except hipBA genes). There are significaut correlation between biofilm for mation and present of QS and TA system genes.
铜绿假单胞菌是一种革兰氏阴性菌，被认为是重要的人类机会致病菌。细菌在不利条件下耐受生存和对抗生素产生抗性的机制之一是通过群体感应（QS）信号和毒素-抗毒素（TA）系统形成生物膜。QS和TA是在生物膜形成中起重要作用的两个系统。QS是一种全局调节机制，使细菌能够通过在群体中产生自诱导物（AI）分子相互通信。由于生物膜形成在铜绿假单胞菌感染中很重要，在此，我们研究了具有生物膜形成能力的铜绿假单胞菌临床分离株中QS和TA基因的频率。
从德黑兰和伊拉姆医院收集了140株铜绿假单胞菌临床分离株。通过生化试验对分离株进行鉴定。采用微孔板法评估生物膜形成。通过煮沸法提取DNA后，通过PCR分析QS基因（lasIR、rhlIR）和TA基因（mazEF、relBE、hipBA、ccdAB和mqsR）的频率。
我们的结果表明，最大耐药性与氨曲南（72.85%）抗生素有关。大多数分离株能够产生生物膜（87.15%），其中大多数形成强生物膜（56.42%）。PCR结果显示，mazEF、relBE、hipBA、ccdAB、mqsR、lasIR和rhlIR基因的频率分别为85.71%、100%、1.42%、100%、57.14%、93.57%和83.57%。
铜绿假单胞菌临床分离株具有很高的生物膜形成能力，这些分离株中的QS和TA系统基因非常高（hipBA基因除外）。生物膜形成与QS和TA系统基因的存在之间存在显著相关性。
