Role of Biofilms in Infections Caused by Escherichia coli
Escherichia coli, probably the best known living organism, is one of the most abundant species of the normal aerobic intestinal flora of humans (about 100 bacteria per gram of faeces) and warm-blooded animals. Unfortunately, E. coli is also a pathogenic organism responsible for numerous infections, causing a range of illnesses from neonatal diarrhea to cystitis and bacteremia. Uropathogenic strains of E. coli account for 70 to 95% of urinary tract infections, one of the most common bacterial diseases. These infections are especially frequent in cases of catheterization. Due to biofilm development on the indwelling catheters, the incidence of infection increases 5 to 10% per day (1). As the general duration is between 2 and 4 days, 15 to 30% of catheterized patients will acquire urinary tract infections. Within 3 weeks of use, 100% of patients with catheters will become infected. A detrimental property of such abiotic surface-associated growth is the expression of biofilm specific characters, such as increased resistance to antibiotics and immunological defenses (2). In order to develop drugs and surface coatings able to delay the contamination of catheters (and therefore to maintain the bacterial sensitivity to antimicrobial agents), it is necessary to understand the physiological
bases of the colonization process and search for molecules capable of interfering with this process (3).