title: Biofilm formation of O157 and non-O157 Shiga toxin-producing Escherichia coli and multidrug-resistant and susceptible Salmonella typhimurium and newport and their inactivation by sanitizers.
abstract: This study compared biofilm formation by 7 serogroups of pathogenic Escherichia coli and 2 or 3 phenotypes of Salmonella (susceptible, multidrug-resistant [MDR], and/or multidrug resistant with ampC gene [MDR-AmpC]). One-week mature biofilms were also exposed to water, quaternary ammonium compound-based (QAC), and acid-based (AB) sanitizers. Seven groups (strain mixture) of above-mentioned pathogens were separately spot-inoculated onto stainless steel coupons surfaces for target inoculation of 2 log CFU/cm2, then stored statically, partially submerged in 10% nonsterilized meat homogenate at 4, 15, and 25 °C. Biofilm cells were enumerated on days 0, 1, 4, and 7 following submersion in 30 mL for 1 min in water, QAC, and AB. Counts on inoculation day ranged from 1.6 ± 0.4 to 2.4 ± 0.6 log CFU/cm2 and changed to 1.2 ± 0.8 to 1.9 ± 0.8 on day 7 at 4 °C with no appreciable difference among the 7 pathogen groups. After treatment with QAC and AB on day 7, counts were reduced (P < 0.05) to less than 0.7 ± 0.6 and 1.2 ± 0.5, respectively, with similar trends among pathogens. Biofilm formation at higher temperatures was more enhanced; E. coli O157:H7, as an example, increased (P < 0.05) from 1.4 ± 0.6 and 2.0 ± 0.3 on day 0 to 4.8 ± 0.6 and 6.5 ± 0.2 on day 7 at 15 and 25 °C, respectively. As compared to 4 °C, after sanitation, more survivors were observed for 15 and 25 °C treatments with no appreciable differences among pathogens. Overall, we observed similar patterns of growth and susceptibility to QAC and AB sanitizers of the 7 tested pathogen groups with enhanced biofilm formation capability and higher numbers of treatment survivors at higher temperatures.
authors.affiliation: Center for Meat Safety and Quality, Dept. of Animal Sciences, Colorado State Univ., Fort Collins, CO 80523-1171, USA.
authors.forename: Aliyar
authors.initials: A
authors.lastname: Fouladkhah
authors.forename: Ifigenia
authors.initials: I
authors.lastname: Geornaras
authors.forename: John N
authors.initials: JN
authors.lastname: Sofos
mesh_terms: D000818:Animals; D018441:Biofilms / Q000254:growth & development*; D015169:Colony Count, Microbial; D004202:Disinfectants / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects*; D019453:Escherichia coli O157 / Q000254:growth & development*; D005506:Food Contamination / Q000517:prevention & control; D005511:Food Handling; D005516:Food Microbiology; D059022:Food Safety; D006863:Hydrogen-Ion Concentration; D008460:Meat / Q000382:microbiology*; D010641:Phenotype; D012486:Salmonella typhimurium / Q000254:growth & development*; D054323:Shiga-Toxigenic Escherichia coli / Q000254:growth & development*; D013193:Stainless Steel
chemical_list: D004202:Disinfectants; D013193:Stainless Steel