RESUMEN
The current study was aimed at investigating the prevalence of the mutations upstream of the oprD coding region and its promoters among imipenem-resistant and sensitive Pseudomonas aeruginosa isolated from educational hospitals in Yazd City, Iran. All isolates were identified by the conventional biochemical tests. Then, the antibiotic resistance of these isolates was determined using the disk diffusion method according to the CLSI guidelines. Also, the E.test was performed to determine the minimum inhibitory concentrations (MIC) of imipenem. The mutations of this gene were recognized by the amplification of this region and subsequently sequenced. Sequencing of the genomic region upstream of oprD these regions were done in the 29 clinical strains. Statistical analysis was done by the statistical software SPSS-18. Seventy (77.7%) of isolates had MIC ≥ 16 and were resistant to imipenem. Mutations of the upstream of the oprD gene and its promoters were seen in 25 (86.2%) isolates and 4 isolates had no mutation. One isolate had a base substitution AâCat nt 25 in the coding region and this isolate had a point mutation leading to an amino acid change at positions 9 (IâL). Our study results indicated that none of the strains had mutation in Shine-Dalgarno and the point mutations were the most common mutations upstream of the oprD coding region among P. aeruginosa isolates. Mutations were observed in imipenem-resistant isolates and it seems this mechanism is effective in resistance of isolates to imipenem and this confirmed that the indiscriminate use of antibiotic should be controlled.
RESUMEN
BACKGROUND AND OBJECTIVES: Antibiotic resistance in Pseudomonas aeruginosa is an increasing health problem. Integrons are associated with a variety of gene cassettes, which confer resistance to multiple classes of antibiotics. This study aimed at screening the presence of class 1, 2 and 3 integrons in P. aeruginosa in Yazd, Iran. MATERIALS AND METHODS: This study was carried out on P. aeruginosa strains from March 2016 to March 2017. Clinical specimens were initially identified by the standard biochemical methods and their resistance patterns to antibiotics were studied using the disc diffusion method. PCR was carried out for the detection of class 1, 2 and 3 integrons using intI1, intI2 and intI3 gene primers, respectively. RESULTS: Antimicrobial susceptibility test showed that 75% of isolates were detected as multi-drug resistant (MDR), and lowest resistance was observed in ciprofloxacin (48.6%) and most resistance was in gentamicin (63.2%). Moreover, PCR results showed that 22 (15.3%) and 119 (82.6%) of P. aeruginosa isolates carried intI2 and intI1 genes, but intI3 gene was not found. CONCLUSION: Since it is customary to observe Class I integrons in P. aeruginosa isolated from clinical samples, they are often responsible for antibiotic resistance gene transfer, which calls for evaluation of integrons as contributing factors in antibiotic resistance.