Bacteria on closed-boll and commercially harvested cotton

The bacterial profile of cotton lint from worldwide origins, and links with occupational lung disease

BACKGROUND

Byssinosis, the cotton worker's lung disease persists today in many countries. Several agents have been investigated with respect to causality; among these are Gram-negative bacteria. These organisms are a source of lipopolysaccharide toxins, which are potentially hazardous to the respiratory tract. Despite byssinosis being most prevalent in countries where adequate preventive procedures are lacking, the majority of past studies have been conducted on cotton from the United States.

METHODS

The current investigation, involved the identification of Gram-negative bacteria from cotton lint samples originating in 12 world regions.

RESULTS

The current investigation, involved the identification of Gram-negative bacteria from cotton lint samples originating in 12 world regions.

CONCLUSIONS

Building a bacterial profile of cotton samples with worldwide origins will be useful in isolating sources of these organisms, assessing the risk posed to industry, workers and ultimately assisting the prevention of byssinosis and related conditions.

Seasonal Dynamics of Bacterial Colonization of Cotton Fiber and Effects of Moisture on Growth of Bacteria within the Cotton Boll

A highly replicated 3-year field study was conducted to determine the seasonal patterns of bacterial colonization of cotton fiber from the time of dehiscence of the bolls (the point at which the bolls just begin to open) through harvest and commercial ginning. Bacterial numbers on fiber samples from 16 plots were determined by dilution pour plating with tryptic soy agar containing cycloheximide, and numbers of gram-negative bacteria were determined by plating on tryptic soy agar containing vancomycin and cycloheximide. Populations of bacteria varied from year to year, but in all three seasons the pattern of colonization was generally a pattern consisting of a rapid increase following opening of the bolls and a more or less stable number thereafter throughout the growing season. Gram-negative bacteria accounted for 50% or more of the recoverable bacterial population. We hypothesized that the luxuriant bacterial flora developed as a result of the availability of sufficient free water in the bolls to allow bacterial proliferation with the carbon sources remaining after fiber maturation. Therefore, laboratory experiments were conducted to determine the threshold moisture level allowing growth of bacteria on fiber in the bolls. Bacterial proliferation occurred when as little as 2% moisture was added to air-dried fiber. Using simulated bolls, we demonstrated bacterial growth resulting from dew formation on fiber held in controlled-humidity chambers.

Toxicity to endothelial cells mediated by cotton bract tannin. Potential contribution to the pathogenesis of byssinosis

Byssinosis is an occupational disease of textile workers caused by exposure to the bract portion of the cotton plant in the form of mill dust. The authors established an in vitro cytotoxicity assay using 51Cr release to assess time- and dose-dependent toxicity of condensed tannin, a component of bracts, on porcine aortic and pulmonary arterial endothelial cells. Tannin produced dose-dependent toxicity to both types of endothelial cells; aortic endothelial cells were more sensitive than were endothelial cells from the pulmonary artery. Skin fibroblasts were relatively insensitive to tannin. Cytotoxicity was not immediate. Release of 51Cr was preceded by a several-hour period during which the endothelial cells underwent profound morphologic changes (as assessed by light and electron microscopy). Even brief exposure of endothelial cells to tannin produced later toxicity and morphologic changes. Condensed tannin causes time- and dose-dependent injury to endothelial cells in vitro at doses potentially achievable in vivo.

Human ventilatory response to washed and unwashed cottons from different growing areas

Thirty volunteer subjects were exposed to controlled amounts of respirable dust generated by the carding of cotton in an experimental cardroom. Eighteen exposures each lasting six hours were performed while carding unwashed and washed cottons from the three major growing regions of the United States. Elutriated dust was analysed gravimetrically and was comparable (0.59 mg/m3 +/- 0.04) for all exposures. Spirometry was recorded before and after each exposure. California cotton resulted in a significantly smaller fall in FEV1 than cotton of the same grade from Texas or Mississippi. All washed cottons resulted in reduced declines when compared with unwashed cottons. For 17 subjects breathing zone personal total dust samples were analysed for airborne endotoxin and compared with the individual's pulmonary function response. A significant correlation between endotoxin exposure and acute decrease in FEV1 was seen. The effect on FEV1 per nanogram of airborne endotoxin was greater for Mississippi cotton than for cotton from the other regions. Airborne endotoxin appears to be an important determinant of acute pulmonary effects of cotton dust. Water washing of cotton results in reduced airborne endotoxin and less bronchoconstriction.

Habitat association of Klebsiella species

The genus Klebsiella is seemingly ubiquitous in terms of its habitat associations. Klebsiella is a common opportunistic pathogen for humans and other animals, as well as being resident or transient flora (particularly in the gastrointestinal tract). Other habitats include sewage, drinking water, soils, surface waters, industrial effluents, and vegetation. Until recently, almost all these Klebsiella have been identified as one species, ie, K. pneumoniae. However, phenotypic and genotypic studies have shown that "K. pneumoniae" actually consists of at least four species, all with distinct characteristics and habitats. General habitat associations of Klebsiella species are as follows: K. pneumoniae--humans, animals, sewage, and polluted waters and soils; K. oxytoca--frequent association with most habitats; K. terrigena--unpolluted surface waters and soils, drinking water, and vegetation; K. planticola--sewage, polluted surface waters, soils, and vegetation; and K. ozaenae/K. rhinoscleromatis--infrequently detected (primarily with humans).