Detection of Class ۱ Integrons among Gram-negative Bacilli Isolated from Sputum Cultures of Patients with Lower Respiratory Tract Infections in Ahvaz, Iran

Introduction: Diffusion of antibiotic resistance genes by horizontal gene transfer has led to the fast emergence of multidrug resistance (MDR) among bacteria. Multiple classes of integrons are effective genetic elements which play a significant role in the acquisition and nosocomial dissemination of resistance factors in strains of Gram-negative bacteria, Pseudomonas aeruginosa, and Acinetobacter baumannii. Methods: In this study, ۱۱۰ sputum samples were collected from hospitalized patients with tract infections. Identification of the isolates was performed by standard biochemical tests. The most frequent Gram-negative isolates were ۲۵ Enterobacteriaceae (۶۲.۵%), (۹ Enterobacter spp, ۱۱ Citrobacter spp, and ۵ Escherichia coli), ۶ P. aeruginosa (۱۵%) and ۹ Acinetobacter spp (۲۲.۵%). Susceptibility of the isolates to antibiotics was carried out by Kirby-Bauer disk diffusion method according to CLSI guidelines, and finally, the class ۱ integrons were detected by PCR. Results: Maximum resistance rate among Gram-negative isolates was observed to ceftazidime, co-trimoxazole, and cefotaxime with ۸۹%, ۸۷%, and ۸۲%, respectively. A low-level resistance was recognized for imipenem ۳۲% and gentamicin ۳۴%, while an intermediate level resistance was found against the norfloxacin ۴۰% and ciprofloxacin ۴۴%. Out of ۶ P. aeruginosa and ۹ A.  baumannii isolates, ۲ (۳۳.۳%) and ۳ isolates (۳۳.۳%) were positive for class ۱ Integrons, respectively, while all Enterobacteriaceae isolates (۱۰۰%) were negative for class ۱ Integrons. Class ۱ integrons were detected among of MDR isolates. Conclusion: Our results showed that monitoring MDR isolates and detection of class ۱ integrons in these isolates is necessary for promotion of antibacterial stewardship.

Keywords:

Class ۱ Integrons , Multidrug Resistance , Pseudomonas aeruginosa , Acinetobacter baumannii , Enterobacteriaceae.