Chloroxylenol-
and triclosan-tolerant bacteria from industrial sources.
by
Lear JC, Maillard JY, Dettmar PW, Goddard PA, Russell AD.
Welsh School of Pharmacy,
Cardiff University,
Cardiff CF10 3XF, UK. J Ind Microbiol Biotechnol. 2002 Nov;29(5):238-42.
ABSTRACT
Potential development of bacterial tolerance to
biocides in the industrial environment is examined in this study.
Bacteria tolerant to the phenolic-type agent para-chloro-meta-xylenol
(PCMX) and the bis-phenol 2,4,4'-trichloro-2'-hydroxydiphenylether
(triclosan) were isolated from industrial sources and identified.
Minimum inhibitory concentrations (MICs) were determined and compared
with those of culture collection (standard) strains. Of around 100
isolates originally obtained, most were naturally tolerant species such
as Pseudomonas spp., or showed low tolerance levels. PCMX-tolerant
isolates of Pseudomonas stutzeri and triclosan-tolerant isolates of
Citrobacter freundii and Acinetobacter johnsonii were retained for
further study. Of these, only P. stutzeri and A. johnsonii showed
elevated tolerance compared with the standard strains. There was no
evidence of tolerance to the other biocide except for Pseudomonas
aeruginosa (an intrinsically tolerant microorganism), and tolerances
were stable in the absence of selective pressure except for A.
johnsonii. Attempts to select or generate increased tolerance in the
standard strains were unsuccessful. High tolerances in terms of MIC
were not reflected in terms of lethal effects. This study did not
produce any evidence suggesting that the presence of residual biocide
concentrations in the industrial environment promotes the emergence of
bacterial tolerance for them.