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Responses of microorganisms to chronic sub-inhibitory exposure to biocides
Başlık:
Responses of microorganisms to chronic sub-inhibitory exposure to biocides
Yazar:
MacLehose, Harriet G., author.
ISBN:
9780355977844
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (290 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Özet:
Where biocides are deployed gradients of concentration will exist from the point of application to the general environment. At particular locations sub-effective concentrations of biocide must co-exist with the resident micro-flora. There is currently expressed concern that exposure of microorganisms to sub-effective concentrations of some biocides might contribute to adaptation of microorganisms to biocides, and subsequent "cross-resistance" to third-party biocides and antibiotics. A treatment cycle employing gradient plates and sequential passage was developed to monitor the response of microorganisms in pure culture to chronic sub-inhibitory exposure to various biocides. Four P. aeruginosa strains were evaluated against six biocides (cetrimide USP, CUSP; chlorhexidine diacetate, CHLX; bronopol; N-methylisothiazol-3-one, MIT; 5-chloro-N-methylisothiazol-3-one, CMIT; benzisothiazol-3-one, BIT). Responses were monitored at each passage in terms of changes in susceptibility to (1) the stressing biocide and (2) third-party biocides and (3) antibiotics. The susceptibility to the stressing biocide reduced for CUSP and CHLX, and in some instances bronopol and CMIT. Susceptibility to third-party biocides either decreased ("cross-resistance") or did not change. All strains "resistant" to CHLX reduced their susceptibility to CUSP, but when "resistant" to CUSP did not alter susceptibility to CHLX. "Cross-resistance" was not therefore necessarily reciprocated. Susceptibility to antibiotics decreased ("cross-resistance"; e.g. CMIT stressed populations to tetracycline), increased (e.g. CUSP and CHLX stressed populations to some beta-lactams) or showed no change. In some instances susceptibility to the stressing biocide did not change but a significant decrease occurred in susceptibility to a third- party biocide or antibiotic (e.g. some bronopol stressed strains to the biocide CMIT and the antibiotic tetracycline). Whilst no visible differences were noted in lipopolysaccharide composition, some changes in outer membrane proteins were noted but did not correlate between strains with particular treatments. Sub-inhibitory biocide concentrations affected colony and cell morphology in some instances. The protection of biofdms against antimicrobial stress was shown to be a function of the total biofilm and not the individual component cells, and the cell-cell signals of P. aeruginosa, homoserine lactones, were suggested not to play major roles in biofilm recalcitrance. The changes in susceptibility noted in this study suggest that caution should be exerted when biocides are used in order to minimise areas of sub-effective exposure.
Notlar:
School code: 1543
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(683820.1) | 683820-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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