BACTERIAL SUCCESSION WITHIN A BIOFILM IN WATER-SUPPLY LINES OF DENTALAIR-WATER SYRINGES

Biofilms have been implicated as reservoirs for bacterial contaminatio n of water delivered by dental air-water syringes. A B-month study was done of bacterial colonization and biofilm formation in plastic water supply lines connected to dental air-water syringes. Changes in biofi lm flora were observed by both scanning electron microscopy and bacter iologic culture. By day 7, many rod- and spiral-shaped bacteria had co lonized tile ridged surface of the luminal wall of the tubing, as reve aled by scanning electron microscopy. By day 30, individual microcolon ies were embedded in extracellular polymeric material. By day 120, the se microcolonies had begun to coalesce, and by day 180 the biofilm had developed into a multilayered, heterogenous mixture of microcolonies. The mean aerobic plate counts of colony-forming units of planktonic a nd biofilm populations were: in log(10) values, 5.9 +/- 0.54/mL and 4. 2 +/- 0.82/cm(2), respectively. Early colonizers were predominantly Ps eudomonas spp., but included Pasteurella, Moraxella, Ochrobactrum, and Aeromonas spp. Flavobacterium and Acinetobacter spp. were observed la ter. Many of these organisms are opportunistic pathogens. These result s demonstrate the longitudinal dynamics of biofilm formation.