Evaluating the Effect of Metal Interference in Inhibition of Biofilm Formation by Uropathogenic Escherichia coli Isolated From Hospitalized Patients

Bacteria that are able to form biofilms can lead to chronic antibiotic-resistant infections and immunomodulatory effects. Iron and other bivalent metals are essential requirements for biofilm formation by bacteria. Escherichia coli is the most predominant agent causing urinary tract infection (UTI). This study aimed to assess the effects of bivalent metals (iron, zinc, cobalt, and copper) on biofilm formation by E. coli isolated from hospitalized patients suffering from UTI. A total of 110 E. coli were isolated from 200 UTI patients referred to Farmanieh hospital in Tehran, Iran. E. coli was confirmed by culture specific media, biochemical tests, and polymerase chain reaction (PCR) analysis. To determine the antibiotic resistance, the Kirby-Bauer disk method was used and the biofilm formation was assessed using microtiter plate assay and electron microscopy. Finally, the data were analyzed via paired t test using the SPSS software. Based on our results, out of 110 urine samples containing E. coli, the highest and the lowest resistance were observed to ampicillin (90%) and amikacin (53%), respectively. The biofilm development was intensified in the presence of glucose and iron. The results also indicated that biofilm formation was inhibited by the use of bivalent metal ions including zinc, cobalt, and copper, with the maximum effect obtained for zinc (P < 0.05). Our work led us to conclude that zinc, cobalt, and copper can inhibit biofilm formation by bacterial strains in medicine.