A prospective study of isolation of Moraxella catarrhalis in a hospital during the winter months.

Sputum samples submitted to the microbiology laboratory from general medical and respiratory wards were monitored for Moraxella catarrhalis on a prospective basis. All isolates were typed by restriction endonuclease typing. Nosocomial spread was found both by the clustering of cases and typing of isolates. Sampling of the environment of some cases was performed. Seven out of 37 samples revealed environmental contamination. Sampling for persistence of the organism in the environment was positive on one occasion out of 13. Evaluation of acquisition of M. catarrhalis in relation to length of stay showed that the average length of stay of a case with M. catarrhalis was considerably longer than average patient stay without M. catarrhalis. Four patients had two isolates available for typing. The type of M. catarrhalis was different on the second occasion to that on the first. Nosocomial spread of M. catarrhalis in the setting of general medical and respiratory wards was found to occur in the winter months.