Effect of EDTA on biofilm formation and antibiotic susceptibility of multidrug resistant uropathogenic Escherichia coli clinical isolates in Egypt

Urinary tract infections are mainly caused by uropathogenic Escherichia coli (UPEC). Biofilm-producer UPEC tends to have a high level of resistance to antibiotics and this leads to recurrent episodes of urinary tract infections. The study tested the effect of a non-antibiotic adjuvant, ethylenediaminetetraacetic acid (EDTA) on the bacterial susceptibility to antibiotics and biofilm formation by multidrug resistant (MDR) strong biofilm producer UPEC from Egypt. The ability for in vitro biofilm formation was detected in 88 MDR UPEC isolates in the absence and presence of two concentrations of EDTA (10 and 20 mM). The minimum inhibitory concentrations (MIC) of the tested antibiotics were detected in the presence and absence of sub-inhibitory concentration of EDTA (2 mM) by the two-fold broth microdilution method. The effect of polyvinylchloride gelatin-EDTA coat on biofilm formation by strong and moderate biofilm producers was tested. The addition of 2 mM EDTA to antibiotics resulted in a decrease in the antimicrobials MIC values with the highest effect recorded with Meropenem (81.6%) and Nitrofurantoin (61.4%). EDTA with concentrations (10 and 20 mM) and Gelatin-EDTA coat inhibited biofilm formation by strong and moderate biofilm producing UPEC by 45.8, 78.8, and 81.1%, respectively. The combination of Carbapenems with EDTA in parenteral preparations to treat life threatening infections could greatly improve the clinical outcome. There is a continuous need for the development of new strategies for treatment of MDR biofilm-producer UPEC.  Novel approaches to control microbial biofilm are needed. Key words: Ethylenediaminetetraacetic acid (EDTA), Escherichia coli, biofilm, antibiotic resistance.