Comparison of three neutralizing broths for environmental sampling of low levels of Listeria monocytogenes desiccated on stainless steel surfaces and exposed to quaternary ammonium compounds

Behavior and Use of Quaternary Ammonium-Based Disinfectants in Biosafety Protocols Against Fusarium oxysporum f. sp. cubense Race 1 and Tropical Race 4

The banana is one of Colombia's main export products. However, production is seriously affected by Fusarium wilt of banana, which is the most destructive disease caused by the fungus Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4). Currently, management strategies focus on containment and biosecurity protocols to prevent its spread to territories that are free of this disease. This study aimed to evaluate nine quaternary ammonium-based disinfectants (i.e., quaternary ammonium compounds [QACs]) in vitro in Colombia on reproductive (microconidia and macroconidia) and resistance structures (chlamydospores) of Foc race 1 (R1) and tropical race 4 (TR4), with and without soil, to determine the influence of organic matter and soil texture on the action of QACs. A method for inhibiting the action of QACs was standardized and evaluated at 1,200 ppm with a contact time of ≤30 s while evaluating the soil-inoculum and soil-disinfectant interactions. In the soil-inoculum interaction, the efficacy of QACs was 100% in the reproductive and resistance structures of Foc R1 and TR4 without soil. However, in the soil-disinfectant interaction, only QAC4 controlled the pathogen at 100%. The presence of organic matter influenced the biocidal action of the QACs, and fine textures had a greater reducing effect on the concentration. The soil decreased the efficacy of the QACs and, therefore, must be removed from contaminated boots before treatments are applied.

Efficacy of a Next Generation Quaternary Ammonium Chloride Sanitizer on Staphylococcus and Pseudomonas Biofilms and Practical Application in a Food Processing Environment

Foodborne pathogens are known to adhere strongly to surfaces and can form biofilms in food processing facilities; therefore, their potential to contaminate manufactured foods underscores the importance of sanitation. The objectives of this study were to (1) examine the efficacy of a new-generation sanitizer (Decon7) on Staphylococcus and Pseudomonas biofilms, (2) identify biofilm bacteria from workers’ boots in relation to previous sanitizer chemistry, (3) validate the efficacy of Decon7 on biofilm from workers’ boots from an abattoir/food processing environment, and (4) compare the sensitivity of isolated boot biofilm bacteria to new- and early (Bi-Quat)-generation QAC sanitizers. Decon7 was applied at two concentrations (5%, 10%) and was shown to be effective within 1 min of exposure against enhanced biofilms of Staphylococcus spp. and Pseudomonas spp. in 96-well microplates. Decon7 was also used to treat workers’ boots that had accumulated high levels of biofilm bacteria due to ineffective sanitization. Bacteria isolated before enzyme/sanitizer treatment were identified through 16S rRNA PCR and DNA sequencing. All treatments were carried out in triplicate and analyzed by one-way RM-ANOVA or ANOVA using the Holm–Sidak test for pairwise multiple comparisons to determine significant differences (p < 0.05). The data show a significant difference between Decon7 sanitizer treatment and untreated control groups. There was a ~4–5 log reduction in Staphylococcus spp. and Pseudomonas spp. (microplate assay) within the first 1 min of treatment and also a > 3-log reduction in the bacterial population observed in the biofilms from workers’ boots. The new next-generation QAC sanitizers are more effective than prior QAC sanitizers, and enzyme pre-treatment can facilitate biofilm sanitizer penetration on food contact surfaces. The rotation of sanitizer chemistries may prevent the selective retention of chemistry-tolerant microorganisms in processing facilities.