In-vitro Studies on Bacterial Biofilm Formation Using Urinary Catheters

Abstract

Though the bacterial united community that lives in a special social pattern, and known as bacterial biofilm is a fascinating phenomenon, yet it might lead to a disastrous outcome. Catheter-associated urinary tract infections due to biofilm formation are rising rapidly, and have a high mortality rate especially in long term catheterized patients. Thus, two types of catheters were used Foley latex 100% silicone coated and, Foley pure silicone size 14 Ch/FR. The most predominant causative agents of catheter-associated urinary tract infection were studied namely Staphylococcus epidermidis and uropathogenic Escherichia coli. The ability to form biofilm on both catheters was investigated, by inoculating each catheter separately with the bacterial species under study. Growth was studied quantitatively by constructing growth curves, and qualitatively by rolling and imprinting the catheter segment over nutrient agar plates. It was noted that latex catheters supported biofilm formation compared to silicon. The treated catheters with three medicinal plant extracts pomegranate (Punnica granatum), guava (Psidium guajava Lim) and cranberry (Vaccinium macrocarpon) compared to the untreated exhibited reduction in bacterial biofilm formation by four to two folds, depending on the tested bacterium, the incubation period and plant used. Simulating the urinary bladder environment, human urine and artificial urine were used as the nutrient fluid. Interestingly, human urine supported the growth of S. epidermidis on latex and silicone catheters, compared to its growth on nutrient broth. However, when E. coli was inoculated on both latex and silicone catheters, grown in artificial urine, viable counts varied significantly in view of the type of catheter. Silicone appeared to retard growth compared to Latex since the maximum population reached after12 hours and declined after 336 hours. Negative staining of the studied catheters using transmission Electron Microscope confirmed the formation of biofilms by S. epidermidis and E. coli. Surprisingly, the same susceptibility pattern of both species was observed before and after forming biofilm.