There were 49 patients with Serratia marcescens infection in a 500-bed hospital. This organism was consistently recovered from the intermittent positive-pressure breathing (IPPB) machines as well as from previously entered vials of saline used for injections and from a jug of saline used for the irrigation of catheters. It is possible that therapists were responsible for cross-contamination of most of these materials. Complete termination of the outbreak took place only after use of the reservoir nebulizer was stopped and all tubing, mouthpieces, exhalation manifold, and medication nebulizers were thoroughly washed and sterilized between each patient use.
Cabrera HA. An Outbreak of Serratia marcescens, and Its Control. Arch Intern Med. 1969;123(6):650-655. doi:10.1001/archinte.1969.00300160040007