The colonization of patients in an intensive treatment unit with gram-negative flora: the significance of the oral route.

An extensive survey of patients and the environment in a newly refurbished intensive care unit showed that the principle species on patients in sites other than the rectum were Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens, Acinetobacter anitratus and Enterobacter cloacae. Multiple episodes of cross-infection were occurring with 10 different strains of these organisms. Three oral solutions (mouthwashes, 'Clinifeeds' and residual water from nasogastric aspiration apparatus) were heavily contaminated with coliforms including some epidemic strains and this corresponded with the finding that colonization with the above species usually occurred first in the mouth or respiratory tract. Attempts to eliminate contamination of the solutions reduced colonization and cross-infection by over 50%, but did not eradicate it. Two sinks without heat-traps on the drains possibly provided a long term reservoir of epidemic strains.