Biofilm formed by Serratia marcescens bacteria on a plastic peg was fixed using glutaraldehyde and Alcian Blue to preserve the bacterial glycocalyx. A human pathogen, S. marcescens are involved in nosocomial infections, particularly catheter-associated bacteremia, urinary tract infections and wound infections, and are responsible for 1.4% of nosocomial bacteremia cases in the United States. They are commonly found in the respiratory and urinary tracts of hospitalized adults and in the gastrointestinal system of children. Due to their ubiquitous presence in the environment, and their preference for damp conditions, S. marcescens are commonly found growing in bathrooms (especially on tile grout, shower corners, toilet water line, and basin), where they manifests as a pink discoloration and slimy film, feeding off phosphorus-containing materials or fatty substances such as soap and shampoo residue. The gram-negative bacteria pictured contained a reddish-orange tripyrrole pigment, prodigiosin, and thus were pink. Enhanced SEM. Image width: 9.14 micrometers. Magnification: 10,940x if the image is printed 10 cm wide.