title: Exposure of Escherichia coli ATCC 12806 to sublethal concentrations of food-grade biocides influences its ability to form biofilm, resistance to antimicrobials, and ultrastructure.
abstract: Escherichia coli ATCC 12806 was exposed to increasing subinhibitory concentrations of three biocides widely used in food industry facilities: trisodium phosphate (TSP), sodium nitrite (SNI), and sodium hypochlorite (SHY). The cultures exhibited an acquired tolerance to biocides (especially to SNI and SHY) after exposure to such compounds. E. coli produced biofilms (as observed by confocal laser scanning microscopy) on polystyrene microtiter plates. Previous adaptation to SNI or SHY enhanced the formation of biofilms (with an increase in biovolume and surface coverage) both in the absence and in the presence (MIC/2) of such compounds. TSP reduced the ability of E. coli to produce biofilms. The concentration of suspended cells in the culture broth in contact with the polystyrene surfaces did not influence the biofilm structure. The increase in cell surface hydrophobicity (assessed by a test of microbial adhesion to solvents) after contact with SNI or SHY appeared to be associated with a strong capacity to form biofilms. Cultures exposed to biocides displayed a stable reduced susceptibility to a range of antibiotics (mainly aminoglycosides, cephalosporins, and quinolones) compared with cultures that were not exposed. SNI caused the greatest increase in resistances (14 antibiotics [48.3% of the total tested]) compared with TSP (1 antibiotic [3.4%]) and SHY (3 antibiotics [10.3%]). Adaptation to SHY involved changes in cell morphology (as observed by scanning electron microscopy) and ultrastructure (as observed by transmission electron microscopy) which allowed this bacterium to persist in the presence of severe SHY challenges. The findings of the present study suggest that the use of biocides at subinhibitory concentrations could represent a public health risk.
authors: Department of Food Hygiene and Food Technology, University of León, León, Spain.
authors: Rosa
authors: R
authors: Capita
authors: Félix
authors: F
authors: Riesco-Peláez
authors: Alicia
authors: A
authors: Alonso-Hernando
authors: Carlos
authors: C
authors: Alonso-Calleja
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development*; D004202:Disinfectants / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology*; D005520:Food Preservatives / Q000494:pharmacology*; D057927:Hydrophobic and Hydrophilic Interactions; D018613:Microscopy, Confocal; D010710:Phosphates / Q000494:pharmacology; D012973:Sodium Hypochlorite / Q000494:pharmacology; D012977:Sodium Nitrite / Q000494:pharmacology; D013499:Surface Properties
chemical_list: D000900:Anti-Bacterial Agents; D004202:Disinfectants; D005520:Food Preservatives; D010710:Phosphates; D012973:Sodium Hypochlorite; D012977:Sodium Nitrite; C018279:sodium phosphate