Pathology of five Scottish deaths from pneumonic illnesses acquired in Spain due to Legionnaires' disease agent

The pathology and histology are reported of five Scots who died of severe pneumonic illnesses after holidays in Spain, three in 1973 and two in 1977. There is strong evidence in favour of all the deaths having been due to the newly discovered Legionnaires' disease (LD) agent. The agent (or its soluble antigen) has been visualised in sections of lung tissue by fluorescent-antibody tests in all cases, and the agent has been identified by the Dieterle silver staining method in small numbers in all cases. Serological testing was possible in three of the patients, and two had very high antibody titres against the LD agent. Apart from the extensive and severe nature of the pathological process there is no feature to distinguish pulmonary infection by this agent from that due to more commonly known bacteria capable of causing lobar pneumonia. The severity and extensive nature of the process is partly a reflection of neglect in seeking treatment until late in the infection, and partly a reflection, as revealed in retrospect, on the use of the wrong antibiotic combination during treatment. Erythromycin has been recommended by other workers as the drug of choice against the LD agent. Infection by this organism is not confined to the USA or to Spain and is indigenous also in the United Kingdom.