فراوانی ژن‌های کد کننده سیتوتوکسین‌های exoT، exoY، exoS وexoU سیستم ترشحی تیپ 3 در سودوموناس آئروجینوزا جدا شده از بیماران سوختگی

Background and Objective: Pseudomonas aeruginosa is an opportunistic pathogen causing nosocomial burn infections. Disease results from the production of numerous virulence factors, some of which are injected directly into the eukaryotic host cells via the type III secretion system (T3SS).The aim of this study was to determine the prevalence of cytotoxins encoding exoT, exoY, exoS and exoU genes among the P. aeruginosa isolated from burn patients. Materials and Methods: Over one year period of study, a total of 95 isolates of P. aeruginosa were collected and identified from burn infections in hospitalized patients. Polymerase chain reaction (PCR)-based method was used for detection of exoT, exoY exoS and exoU genes. According to CLSI (Clinical Laboratory Standards Institute) guidelines antimicrobial susceptibility testing was performed by disc diffusion method against 10 antibiotics. The data were analyzed by χ2 test. A p value of <0.05 was considered as statistically significant. Results: All of the isolates of P. aeruginosa contained exoT gene while exoY gene was detected in 69.5 % of isolates. The prevalence of exoU and exoS genes was 44.1% and 35.8%, respectively. 8.42% of isolates harbored all of the four genes. Coexistence of exoS and exoU was seen in 10.5% of the isolates. High resistance rates were seen for cefipime, Azteronam and Ofloxacin. Conclusion: Considering the low prevalence of exoS in P. aeruginosa causing burn infection in comparison with other infections caused by this bacterium, it seems that this gene has a minor role in the P. aeruginosa pathogenesis isolated from burn infection. Instead, exoT and exoY were found in nearly all isolates and probably, these genes may have a greater role in burn infections. References 1- Veesenmeyer JL, Hauser AR, Lisboa T, Rello J. Pseudomonas aeruginosa virulence and therapy: evolving translational strategies. Crit Care Med. 2009 37: 1777-86. 2- Jabalameli F, Mirsalehian A, Sotoudeh N, et al. Multiple-locus variable number of tandem repeats (VNTR) fingerprinting MLVF and antibacterial resistance profiles of extended spectrum beta lactamase (ESBL) producing Pseudomonas aeruginosa among burnt patients in Tehran. Burns. 2011 37: 1202-7. 3- Ranjbar R, Owlia P, Saderi H, et al. Characterization of Pseudomonas aeruginosa strains isolated from burned patients hospitalized in a major burn center in Tehran, Iran. Acta Med Iran. 2011 49: 675-9. 4- Branski LK, Al-Mousawi A, Rivero H, Jeschke MG, Sanford AP, Herndon DN. Emerging infections in burns. Surg Infect (Larchmt). 2009 10: 389-97. 5- Mesaros N, Nordmann P, Plésiat P, et al. Pseudomonas aeruginosa: resistance and therapeutic options at the turn of the new millennium. Clin Microbiol Infect. 2007 13: 560-78. 6- Roy-Burman A, Savel RH, Racine S, et al. Type III protein secretion is associated with death in lower respiratory and systemic Pseudomonas aeruginosa infections. J Infect Dis. 2001 183: 1767-74. 7- Engel J, Balachandran P. Role of Pseudomonas aeruginosa type III effectors in disease. Curr Opin Microbiol. 2009 12: 61-6. 8- Gala´n JE, Collmer A. Type III secretion machines: bacterial devices for protein delivery into host cells. Science. 1999 284: 1322-28. 9- Galle M, Carpentier I, Beyaert R. Structure and function of the Type III secretion system of Pseudomonas aeruginosa. Curr Protein Pept Sci. 2012 13: 831-42. 10- Lin HH, Huang SP, Teng HC, Ji DD, Chen YS, Chen YL. Presence of the exoU gene of Pseudomonas aeruginosa is correlated with cytotoxicity in MDCK cells but not with colonization in BALB/c mice. J Clin Microbiol. 2006 44: 4596-7. 11- Lee VT, Smith RS, Tu¨ mmler B, Lory S. Activities of Pseudomonas aeruginosa effectors secreted by the type III secretion system in vitro and during infection. Infect Immun. 2005 73: 1695-705. 12- Hauser AR. The type III secretion system of Pseudomonas aeruginosa: infection by injection. Nat Rev Microbiol. 2009 7: 654-65. 13- Shen DK, Quenee L, Bonnet M, et al. Orf1/SpcS chaperones ExoS for type three secretion by Pseudomonas aeruginosa. Biomed Environ Sci. 2008 21: 103-9. 14- Radke J, Pederson KJ, Barbieri JT. Pseudomonas aeruginosa exoenzyme S is a biglutamic acid ADP-ribosyltransferase. Infect Immun. 1999 67: 1508-10. 15- Garrity-Ryan L, Kazmierczak B, Kowal R, Comolli J, Hauser A, Engel JN. The arginine finger domain of ExoT contributes to actin cytoskeleton disruption and inhibition of internalization of Pseudomonas aeruginosa by epithelial cells and macrophages. Infect Immun. 2000 68: 7100-13. 16- Barbieri JT, Sun J. Pseudomonas aeruginosa ExoS and ExoT. Rev Physiol Biochem Pharmacol. 2004 152: 79-92. 17- Yahr TL, Vallis AJ, Hancock MK, Barbieri JT, Frank DW. ExoY, an adenylate cyclase secreted by the Pseudomonas aeruginosa type III system. Proc Natl Acad Sci USA. 1998 95: 13899-904. 18- Cowell BA, Evans DJ, Fleiszig SMJ. Actin cytoskeleton disruption by ExoY and its effects on Pseudomonas aeruginosa invasion. FEMS Microbiol Lett. 2005 250: 71-76. 19- Sitkiewicz I, Stockbauer KE, Musser JM. Secreted bacterial phospholipase A2 enzymes: better living through phospholipolysis. Trends Microbiol. 2007 15: 63-69. 20- Rabin SD, Hauser AR. Functional regions of the Pseudomonas aeruginosa cytotoxin ExoU. Infect Immun. 2005 73: 573-82. 21- Feltman H, Schulert G, Khan S, et al. Prevalence of type III secretion genes in clinical and environmental isolates of Pseudomonas aeruginosa. Microbiology. 2001 147: 2659-69. 22- Kudoh I, Wiener-Kronish JP, Hashimoto S, Pittet J F, Frank D. Exoproduct secretions of Pseudomonas aeruginosa strains influence severity of alveolar epithelial injury. Am J Physiol. 1994 267: 551-6. 23- Kurahashi K, Kajikawa O, Sawa T, et al. Pathogenesis of septic shock in Pseudomonas aeruginosa pneumonia. J Clin Invest. 1999 104: 743-750. 24- Clinical Laboratory Standards Institute, Performance standards for antimicrobial susceptibility testing twenty-first informational supplement. vol. 31, 2011, pp. M100-M121. 25- Jabalameli F, Mirsalehian A, Khoramian B, et al. Evaluation of biofilm production and characterization of genes encoding type III secretion system among Pseudomonas aeruginosa isolated from burn patients. Burns. 2012 38: 1192-7. 26- Fatholahzadeh B, Hashemi FB, Emaneini M, Aligholi M, Nakhjavani FA, Kazemi B. Detection of vancomycin resistant enterococci (VRE) isolated from urinary tract infections (UTI) in Tehran, Iran. DARU J Pharm Sci. 2006 14: 141-5. 27- Wong-Beringer A, Wiener-Kronish J, Lynch S, Flanagan J. Comparison of type III secretion system virulence among fluoroquinolone-susceptible and -resistant clinical isolates of Pseudomonas aeruginosa. Clin Microbiol Infect. 2008 14: 330-6. 28- Strateva T, Markova B, Ivanova D, Mitov I. Distribution of the type III effector proteins-encoding genes among nosocomial Pseudomonas aeruginosa isolates from Bulgaria. Annals Microbiol. 2010 60: 503-50. 29- Jain M, Ramirez D, Seshadri R, et al. Type III secretion phenotypes of Pseudomonas aeruginosa strains change during infection of individuals with cystic fibrosis. J Clin Microbiol. 2004 42: 5229-37. 30- Azargoon R, Doustdar F, Khanbabaei G, Ghazi M, Mehrnejad F, Goudarzi H. Type III secretion system characterization of Pseudomonas aeruginosa isolates associated with cystic fibrosis. Pejouhesh. 2013 37: 189-193. 31- Choy MH, Stapleton F, Willcox MD, Zhu H. Comparison of virulence factors in Pseudomonas aeruginosa strains isolated from contact lens- and non-contact lens-related keratitis. J Med Microbiol. 2008 57: 1539-46. 32- Moradian Kouchaksaraei F, Ferdosi Shahandashti E, Molana Z, et al. Molecular detection of integron genes and pattern of antibiotic resistance in Pseudomonas aeruginosa strains isolated from intensive care unit, Shahid Beheshti hospital, north of Iran. Int J Mol Cell Med. 2012 1: 209-17. 33- Mirsalehian A, Feizabadi M, Nakhjavani FA, Jabalameli F, Goli H, Kalantari N. Detection of VEB-1, OXA-10 and PER-1 genotypes in extended-spectrum beta-lactamase-producing Pseudomonas aeruginosa strains isolated from burn patients. Burns. 2010 36: 70-4.