Serratia marcescens is a species of
rod-shaped Gram negative bacterium in the family
Enterobacteriaceae. A
human pathogen,
S. marcescens is involved in
hospital-acquired infections (HAIs), particularly catheter-associated
bacteremia,
urinary tract infections and
wound infections, and is responsible for 1.4% of HAI cases in the United States. It is commonly found in the
respiratory and
urinary tracts of hospitalized adults and in the
gastrointestinal system of children. Due to its abundant presence in the environment, and its preference for damp conditions,
S. marcescens is commonly found growing in bathrooms (especially on tile grout, shower corners, toilet water line, and basin), where it manifests as a pink, pink-orange, or orange discoloration and slimy film feeding off phosphorus-containing materials or fatty substances such as soap and shampoo residue.