Serotyping in epidemiological tracing of nosocomially acquired Proteus mirabilis in a geriatric ward.

Samples taken from patients, staff, and hospital milieu at intervals of two weeks for 41 weeks were analysed for nosocomial spread of Proteus mirabilis. Eighty-eight per cent of 3,519 colonies were serotyped into 21 0 groups. By O grouping and H typing, nosocomial spread of P. mirabilis could be demonstrated in several cases between patients in the same room. No spread between rooms was found. The acquisition of P. mirabilis between patients probably occurred as the result of cross-infection due to inadequate nursing technique.