Alterations of gene expression levels in uropathogenic Escherichia coli by antibiotics at subinhibitory concentrations

Background and Aim : Urinary tract infection (UTI) caused by Escherichia coli remains an important health problem. Bacteria in the urinary tract may be exposed to sub-minimum inhibitory concentrations (sub-MICs) of antibiotics. Our aim was to investigate the possible changes in presence of virulence genes within the presence of antibiotics in UTI-associated E. coli.Methods : A total of ۹۹ E. coli isolated from UTI in Sanandaj, Iran were examined for susceptibility to antibiotics using the disk diffusion method and possession of virulence genes by PCR. Expression changes were measured in sub-MICs of antibiotic. Total RNA were isolated from ۰.۲۵ sub-MICs and gene expression levels were determined by quantitative PCR. P value was set at ۰.۰۵.Results : Out of the ۹۹ isolates, ۳۶.۴% carried pap adhesin, ۲۳.۲% carried hlyA hemolysin, ۲۱.۲% carried cnf toxin, and ۹.۱% carried afa adhesin. The prevalence of hly in the ceftriaxone- susceptible isolates was significantly higher than in the -resistant isolates (P< ۰.۰۵). Therefore, the alteration of hly expression level at ۰.۲۵ sub-MICs of ceftriaxone in seven hly-positive strains was investigated. The MIC values of ceftriaxone were from ۰.۰۳ to ۰.۱۲۵ µg/ml depending on the isolate. For all strains, ceftriaxone dramatically reduced mRNA levels of HlyA compared to that of the untreated control (from ۹۰% to ۵%, depending on the strain). Conclusion : The results showed that antibiotics may play a role in determination of the pathogenicity of E. coli and therefore the outcome of infection.

کلیدواژه ها:

Escherichia coli ، gene expression ، antibiotic resistance ، hemolysin