Abundant biofilm of Escherichia coli is clearly visible on siliconized latex surface. A 1-cm2 piece of siliconized latex was incubated in LB Broth, Lennox (Fisher Scientific, Fairlawn, NJ) with E coli J96 (uropathogenic strain) for 2 days at 37°C with broth changes twice daily. Squares were removed and rinsed 4 times with phosphate-buffered saline. A 20-μM solution of DRAQ5 (Biostatus Ltd, Leicestershire, United Kingdom) was applied directly to each square. DRAQ5 (Biostatus Ltd) was chosen to bind cellular DNA, which in E coli fills nearly entire cell. Examination of stained squares was performed using confocal laser-scanning microscope (LSM 510, Zeiss, Jena, Germany). System consisted of laser-scanning module mounted on inverted microscope (Axiovert 100 M BP, Zeiss), and argon laser (488 nm) and helium-neon laser (633 nm). Oil objective was 63x. Images were recorded at excitation wavelength of 633 nm and emission wavelength of 647 to 722 nm. Images were stored and viewed with software (LSM 5, Zeiss).