Incidence of Pathogenic Staphylococci in a Group of Northern Ireland Munition Workers

DURING the winter of 1939-40 a number of men working in a munition factory attended at the skin department of the Royal Victoria Hospital, Belfast, where they were seen by Dr. Ivan McCaw. They were suffering from staphylococcal lesions of the skin of the arms and thighs, which varied in severity from mild folliculitis with acne to severe boils. During work, the skin of the parts affected was in continuous contact with mineral oil and the clothing of the men examined was soaked with oil. Since it has been shown by Hart (1937), Hallman (1937), McFarlane (1938), and others that carriers of pathogenic staphylococci are relatively common in groups of normal persons, an investigation was begun somewhat on the lines of that carried out by Gillespie, Devenish, and Cowan (1939) to determine the carrier-rate among the men exposed to oil, and if possible to discover the reason for the high incidence of skin lesions among these workers. Cultures were made from the nasal cavities, normal skin, and any existing lesion, whether slight or severe. The swabs were planted on blood-agar, incubated at 37°C. for twenty-four hours, and then kept under observation from four to seven days on the bench. Likely colonies of creamy or golden colour were picked off for investigation, and if no creamy colonies were present, white colonies were taken instead. In all the colonies selected the presence or absence of haemolysis on blood-agar was noted. Three hundred and sixty-three strains were isolated and studied. They were tested for their ability to ferment mannite and to coagulate human plasma. Most strains were also tested for the presence of alpha haemolysin. These tests were carried out according to the methods described by Gillespie, Devenish, and Cowan (1939) in their investigation on a group of medical students attending University College Hospital, London. Since it has been established by Cruickshank (1937), Chapman et al. (1938), and Gillespie, Devenish, and Cowan (1939), that the presence of coagulase is a reliable criterion for the pathogenicity of staphylococci, the test for this substance was used to determine the pathogenicity of the strains investigated. In biological properties, the results attained were similar to those publishedby Gillespie, Devenish, and Cowan (1939). One albus strain of nasal origin gave a positive coagulase test, and so may be regarded as a potential pathogen. Devenish and Miles (1939) classified coagulase positive albus strains in the aureus group. Eighty-two men submitted themselves for examination. Their ages ranged from 15 to 62 years, but most were 19 to 20 years old.