The potential for biocide tolerance in Escherichia coli and its impact on the response to food processing stresses

Exposure of Escherichia coli ATCC 12806 to Sublethal Concentrations of Food-Grade Biocides Influences Its Ability To Form Biofilm, Resistance to Antimicrobials, and Ultrastructure

“…An increase in E. coli tolerance to biocides after exposure to sublethal concentrations has been demonstrated widely for triclosan, benzalkonium chloride, and chlorhexidine (14,49). In order to avoid an increase in biocide tolerance, several biocidal agents (with various modes of action on their microbial target organisms) should be combined in the development of commercial biocides (50).…”

“…In order to avoid an increase in biocide tolerance, several biocidal agents (with various modes of action on their microbial target organisms) should be combined in the development of commercial biocides (50). Moreover, the consequences of adaptation can be limited by alternating the formulations used over time (14).…”

Transcriptomic Analysis of Triclosan-Susceptible and -Tolerant Escherichia coli O157:H19 in Response to Triclosan Exposure

“…34 T3 5H5 (triclosan MIC 6.25 mg/ml) was subjected to selection using stepwise increments in triclosan concentration to generate a mutant strain, denoted as T3 5H5M, with enhanced tolerance to triclosan (MIC > 8,000 mg/ml), which remained stable on subculturing for a period of at least 7 days in the absence of triclosan. 32 The wild-type strain and triclosan-tolerant mutant were subcultured in parallel with the presence of triclosan being the only difference. Bacterial cultures were routinely stored on Protect TM beads (Technical Service Consultants) and maintained frozen at -80°C.…”

“…2,6,21 A study by our group examining the baseline tolerance of a panel of verocytotoxigenic E. coli (VTEC) isolated from Irish beef abattoirs (n = 99) to eight commercial biocide formulations currently used in the cleaning regimes of food plants in Ireland found that none of the isolates tested grew above the working concentration recommended by the manufacturers of these products. 32 The potential for isogenic mutants with enhanced biocide tolerance to be selected after daily sub-culture into increasing concentrations of commercial biocides and three biocidal active agents was investigated in the same study and through these experiments, a mutant E. coli O157:H19 isolate was identified (and denoted as T3 5H5M) which displayed stable increased tolerance to triclosan that was > 1,280-fold higher than the wild-type (denoted as T3 5H5). Although numerous studies have examined the phenotypic tolerance of bacterial isolates to triclosan and their cross-resistance to clinically relevant antibiotics, a few have investigated differences in gene expression between a stable mutant displaying high-level tolerance to triclosan and its isogenic triclosan-susceptible wild-type in response to triclosan stress.…”

Comparative proteomic analysis of Salmonella tolerance to the biocide active agent triclosan

“…Further work is required in order to ascertain whether mutations in Salmonella leading to increased efflux, a reduction in bacterial cell permeability, and enhanced communication through QS are associated with modifications in other relevant phenotypes previously found, or suggested, to be altered with biocide exposure or tolerance. Examples include an increased multicellular and aggregative behaviour [49], persistence [50,51] or an altered virulence potential [52][53][54].…”