Investigation into the effect of detergents on disinfectant susceptibility of attached Escherichia coli and Listeria monocytogenes.
OBJECTIVE
Investigate the effect of detergent treatment on susceptibility of attached Escherichia coli and Listeria monocytogenes to subsequent disinfectant treatment.


RESULTS
Plate counts show that E. coli attached to stainless steel surfaces became significantly more susceptible to benzalkonium chloride (BAC) after treatment with sodium alkyl sulfate (SAS) and fatty alcohol ethoxylate (FAE). No change in susceptibility was observed with Sodium dodecyl sulfate (SDS). L. monocytogenes became significantly less susceptible to BAC after treatment with SAS and SDS yet no change in susceptibility was observed with FAE. Flow cytometry using the fluoresceine propidium iodide revealed significant increases in cell membrane permeability of both organisms by SAS and FAE, although the effect was much greater in E. coli. No change was observed with SDS. Hydrophobic interaction chromatography showed that both organisms became less hydrophobic following treatment with SAS and SDS but FAE had no effect.


CONCLUSIONS
In E. coli, detergents that increase susceptibility to BAC increase membrane permeability. In L. monocytogenes, detergents that reduce susceptibility to BAC lower cell surface hydrophobicity.


CONCLUSIONS
Detergents can influence the sensitivity of pathogenic food borne micro-organisms to BAC.
Walton
J T
JT
School of Applied Sciences, Research Institute in Healthcare Science, University of Wolverhampton, Wolverhampton, UK.
Hill
D J
DJ
Protheroe
R G
RG
Nevill
A
A
Gibson
H
H
D001422:Bacterial Adhesion / Q000187:drug effects; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003902:Detergents / Q000494:pharmacology*; D004202:Disinfectants / Q000494:pharmacology*; D004866:Equipment Contamination / Q000517:prevention & control*; D004926:Escherichia coli / Q000187:drug effects*; D005434:Flow Cytometry; D005516:Food Microbiology; D057927:Hydrophobic and Hydrophilic Interactions; D008089:Listeria monocytogenes / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D013193:Stainless Steel
D001548:Benzalkonium Compounds; D003902:Detergents; D004202:Disinfectants; D013193:Stainless Steel