Timber-colonizing gram-negative bacteria as potential causative agents of respiratory diseases in woodworkers

Abstract

Occurrence Gram-negative bacteria occur commonly in the inner tissues of stored coniferous and deciduous timber, showing a marked variation in numbers. The greatest maximal numbers are found in the sapwood of coniferous timber. The common constituents of the Gram-negative biota are potentially pathogenic species of Enterobacteriaceae family of the genera Rahnella, Pantoea, Enterobacter, and Klebsiella. The air of wood-processing facilities is polluted with the wood-borne Gram-negative bacteria and produced by them endotoxin, as demonstrated worldwide by numerous studies. Effects There are three potential pathways of the pathogenic impact of wood-borne Gram-negative bacteria on exposed woodworkers: allergic, immunotoxic, and infectious. Allergic impact has been underestimated for a long time with relation to Gram-negative bacteria. Hopefully, the recent demonstration of the first documented case of hypersensitivity pneumonitis (HP) in woodworkers caused by Pantoea agglomerans which developed in extremely large quantities in birch sapwood, would speed up finding of new wood-related cases of HP caused by Gram-negative bacteria. The second pathway is associated with endotoxin, exerting strong immunotoxic (excessively immunostimulative) action. It has been demonstrated that endotoxin is released into wood dust in the form of nano-sized microvesicles, by peeling off the outer membrane of bacteria. Endotoxin microvesicles are easily inhaled by humans together with dust because of small dimensions and aerodynamic shape. Afterwards, they cause a nonspecific activation of lung macrophages, which release numerous inflammatory mediators causing an inflammatory lung reaction, chest tightness, fever, gas exchange disorders, and bronchospasm, without radiographic changes. The resulting disease is known as “Organic Dust Toxic Syndrome” or “toxic pneumonitis.” The potential third pathway of pathogenic impact is infection. The suspected species is Klebsiella pneumoniae that may occur commonly in wood dust; however, until now this pathway has not been confirmed. Conclusion Summarizing, Gram-negative bacteria-inhabiting timber should be considered, besides filamentous fungi and actinobacteria, as important risk factors of occupational disease in woodworkers that could be either HP with allergenic background or toxic pneumonitis elicited by endotoxin.

Evaluation of occupational exposure to wood dust among sawmill workers within the Gert Sibande District Municipality, South Africa

“…organic dust toxic syndrome (ODTS) [14,15,16,17,18,19]. It has been demonstrated recently that Gram-negative (Gram-) bacteria and actinobacteria present in wood dust may cause hypersensitivity pneumonitis [20], whereas endotoxin (cell wall lipopolysaccharide) produced by Gram-bacteria may be a common cause of ODTS [21]. Belin and Land et al carried out a study at Swedish sawmills and found that the kiln drying was contributing factor to the high mould exposure in the trimming departments [22,23].…”

Wood dust and asthma

“…Timber-colonizing gram-negative bacteria are found in high numbers in sapwood of coniferous timber. Common bacteria include Enterobacteriaceae family of the genera of Rahnella , Pantoea , Enterobacter and Klebsiella [6]. During industrial processing endotoxin is released into wood dust as nano-sized microvesicles.…”

“…A review of occupational exposures to wood dust in the European Union suggested that workers in construction, furniture, builders' carpentry, joinery, sawmilling and forestry were the highest exposed [5]. Furthermore, high exposures have also been reported in plywood and chipboard factories, pulp and paper mills, composting, wood pellet production, and use of wood chips in biofuel or bedding for animals [2,6]. Studies on the African continent have also reported excessive dust exposures in small to large-scale wood factories and particleboard companies [1].…”

Prokaryote communities associated with different types of tissue formed and substrates inhabited by Serpula lacrymans

“…Some Pseudomonadota and other prokaryotes are able to obtain nutrients via mycophagy, which from the fungal viewpoint, is the negative end of interactions (Tláskal & Baldrian, 2021). Bacteria belonging to the genera Bacillus , Pseudomonas , Alcaligenes , Serratia, Streptomyces , Erwinia and Enterobacteria , among others, have been shown to play a role in the deterioration of building timber (Boutelje & Bravery, 1968; Dutkiewicz et al, 1992; Gaylarde & Morton, 1999; Line, 2003; Rogers & Baecker, 1991; Wójcik‐Fatla et al, 2022).…”