One hundred and eleven consecutive deaths in seven mental hospitals during the months of February to October 1967 were investigated histologically and bacteriologically.
Bacteria were present in the lung tissue significantly more frequently when inflammation was present than when it was absent and the differences were significant for both Escherichia coli and Staphylococcus aureus; E. coli was isolated from 22(34%) of the 65 patients with inflamed lungs compared with two (4%) of 46 control patients and the corresponding figures for Staph. aureus were 20(31%) of 65 patients compared with seven (15%) of 46 control patients.
Some strains of E. coli were serotyped using antisera against 0 antigens 1, 4, 6, 18ab, 18ac, 25, 50, 65, 69 and 75 and the strains most commonly found in the inflamed lungs, spleens and other inflammatory lesions of 25 patients were 06, 018 and 075. These strains were isolated more frequently from these sites than from the faeces of a group of 19 patients with no such lesions.
In this series E. coli was the commonest organism to be associated with terminal bronchopneumonia and the possible reasons for this are discussed.