Bacterial Culture of Cotton

Bacterial contamination of various parts of the cotton plant and of cotton from different mills was investigated. The predominant bacterial species were Gram-negative rods mainly of the Enterobacter genus. When guinea pigs inhaled strains of these bacteria cultivated from cotton, a strong leucocyte mobilising capacity was found for Pseudomonas and Enterobacter but not for Agrobacterium or Bacillus species. The aetiology of the development of pulmonary symptoms after inhalation of bacteria-containing dusts and subsequent production of endotoxins is discussed. The presence of airborne Gram-negative bacteria in cotton mills was first reported by a commission investigating working conditions in cotton mills in Great Britain (Home Office, 1932). The importance of the bacterial contamination of cotton dust in the development of pulmonary symptoms after acute and subchronic exposure has since been investigated by several workers. Schneiter et al. (1942) found up to 107 colonies per gram of cotton sampled from different mills. Bacterial strains of the genus Enterobacter were found in cotton materials reported to have adversely affected exposed workers. An endotoxin-like substance was demonstrated in filtrates from saline extracts of stained cotton. Pernis et al. (1961), and Cavagna et al. (1969), suggested bacterial endotoxin as a causative agent in occupational disease following the inhalation of vegetable dusts, particularly cotton dusts. This hypothesis was rejected by Antweiler (1961) and results from in vivo and in vitro experiments reported by Tuffnell (1960) did not incriminate bacteria in the development of pulmonary symptoms. In animals, acute or chronic exposure to water extracts of bale cotton, bract or a bract aerosol will cause an increase in the number of polymorphonuclear leucocytes (PMN) in the airways a few hours after exposure (Rylander and Nordstrand, 1974). This increase reaches a peak at 24 hours after exposure, with a subsequent decline in PMN. During a three-week exposure period the number of PMN remained at an increased level but fell within a Received for publication 20 September 1977 Accepted for publication 18 January 1978 few days of cessation of exposure (Rylander and Snella, 1976). The leucocyte mobilising reaction occurs in several different animal species (Walker et al., 1975) and in man (Merchant et al., 1975). A close correlation was found between the number of airborne Gram-negative bacteria and the prevalence of byssinosis in an epidemiological study in different cotton mills (Cinkotai et al., 1977). In view of the apparent importance of the bacterial contamination of cotton in the development of pulmonary symptoms, the bacteria on different cotton plants and bale cotton were studied. The number of viable bacteria and the species were determined. The reactions after acute exposure to bacteria typically found on cotton were studied in animal experiments. Materials and methods BACTERIAL CULTURE OF COTTON Samples of cotton plants, bale cotton and cotton from blending machines, card rooms and waste from cards were collected from different cotton mills. One gram of the sample was suspended in 10 ml 0 9 % NaCl and shaken vigorously. The liquid was squeezed out of the sample, then put back and shaken again. Serial dilutions of the extracts were plated on nutrient agar. blood agar or Drigalski agar selective for Gram-negative rods and incubated at 37°C overnight. The total number of colony-forming units (cfu) was counted. Pilot experiments showed that incubation at 200C and 300C gave the same number of cfu. All samples were prepared in duplicate and the results were expressed as the mean number of cfu/g 204 group.bmj.com on September 7, 2017 Published by http://oem.bmj.com/ Downloaded from