Detection of class 1 integrons-mediated antibiotic resistance among commensal Escherichia coli

ABSTRACT

Normal intestinal microbiota are a reservoir for resistant genes especially Escherichia coli. The aim of this study was to investigate the prevalence of class 1 integrons and antibiotic resistance in commensal E. coli isolates. Also, this study aimed to detect the association of class 1 integrons with antibiotic resistance [single and multiple drug resistance]. Two hundred E. coli isolates from stools were obtained from different 4 groups [children with and without previous antibiotic treatment and elderly hospitalized and healthy individuals, each group included 50 individuals]. All isolates were tested for their susceptibility against 15 antimicrobial agents using standard disc diffusion method and for the presence of class I integrons by PCR using the following primers; 5'CS 5'GGCATCCAAGCAGCAAG-3' and 3'CS 5'AAGCGAC7TGACCTGA-3'. This study revealed that out of the 200 E. coli isolates, III isolates [55.5%] carried class I integrons genes. Comparing children with and without antibiotic treatment, antibiotic-treated ones had a significantly higher frequency of integrons carriage than antibiotic-naïve group [72% versus 64%, P = 0.039]. Evaluating medical interventions, this study detected that the frequency of integrons in E. coli isolates from hospitalized elderly persons was higher compared with non-hospitalized ones [68% versus 18%, P<0.001]. Also, a significant higher frequency of integrons bearing strains was found in antibiotic-naive children than in healthy elderly persons [64% versus 18%, P<0.001]. The majority [82.9%] of isolates were resistant to at least one antimicrobial agent with the following percent resistance, sulfamethoxazole [61%], and trimethoprim-sulfamethoxazole/e [52.5%] ampicillin [40.5%], streptomycin [35%], ampicillin-sulbactam [30%], tetracycline [30%], tobramycin [29%], amikacin [26%] gentamycin [19.5%], nalidixic acid [12.5%] cefuroxime [12.5%], ciprofloxacin [10.5%], cefotaxime [9.5%], cefepime [4.5%] and imipenem [4%]. The most frequent pattern of multidrug resistance E.coli isolates [19.5%] was sulfamethoxazole/e, trimethoprim-sulfamethoxazole/e, ampicillin, and ampicillin-sulbactam. Multiple drug resistance was more frequent in integrons- positive isolates [82.9%] than in integrons-negative E. coli [42. 7%], [P = 0.001]. In conclusion, the prevalence of integrons, n commensal E. coli strains in persons without medical intervention depended on age. Hospitalization and antibiotic administration were influencing factors that affected the frequency of integrons carriage. Human fecal E. coli is a reservoir of antibiotic-resistant genes that has a significant risk of the spread of. microbial resistance in the community