Frequency of exoT and exoS Genes among Pseudomonas Aeruginosa Isolates and Antibiotic Resistance in Burn Patients in Sari Zare Hospital, Iran

Background and Pseudomonas aeruginosa is one of the most important pathogens of burn infections in hospitals. It causes infection by producing some virulence factors such as exoS and exoT cytotoxins. The aim of this study was to evaluate the frequency of exoS and exoT genes among P.aeruginosa isolated from wound infections in burn patients and the relationship between the presences of these genes and antibiotic resistance.
In this descriptive cross-sectional study, the wounds of 80 burned patients in Sari Zare Hospital were sampled during April, May, and June 2016. After identification by biochemical tests, 18 isolates of P.aeruginosa were obtained. Antimicrobial susceptibility to 8 antibiotics was determined by disk diffusion method. PCR was performed for detection of exoS and exoT genes. Data was analyzed in SPSS V21 applying Chi-square. The significance level was considered at P A total of 18 isolates was investigated from which 15 (83.5%) had exoT gene and 14 isolates (77.8%) had exoS gene. Simultaneous presence of these genes was seen in 13 (72.5%) isolates. Statically, resistance against Ampicillin, Cephalexin, Co-trimoxazol, and Cefazolin was significantly correlated with the presence of exoS and exoT genes (P = 0.0184, P =0.0047, respectively). In addition, resistance against Imipenem was significantly correlated with the presence of exoT (P=0.0489).
High prevalence of exoS and exoT among Pseudomonas aeruginosa isolates (72.5%) and the significant differences between presence of these genes and antibiotic resistance indicate the importance of these two genes in burn infections.