ABSTRACT
ABSTRACT: The SARS-CoV-2 pandemic has presented new challenges to food manufacturers. During the early phase of the pandemic, several large outbreaks of coronavirus disease 2019 (COVID-19) occurred in food manufacturing plants resulting in deaths and economic loss, with approximately 15% of personnel diagnosed as asymptomatic for COVID-19. Spread by asymptomatic and presymptomatic individuals has been implicated in large outbreaks of COVID-19. In March 2020, we assisted in implementation of environmental monitoring programs for SARS-CoV-2 in zones 3 and 4 of 116 food production facilities. All participating facilities had already implemented measures to prevent symptomatic personnel from coming to work. During the study period, from 17 March to 3 September 2020, 1.23% of the 22,643 environmental samples tested positive for SARS-CoV-2, suggesting that infected individuals were actively shedding virus. Virus contamination was commonly found on frequently touched surfaces such as doorknobs, handles, table surfaces, and sanitizer dispensers. Most processing plants managed to control their environmental contamination when they became aware of the positive findings. Comparisons of positive test results for plant personnel and environmental surfaces in one plant revealed a close correlation. Our work illustrates that environmental monitoring for SARS-CoV-2 can be used as a surrogate for identifying the presence of asymptomatic and presymptomatic personnel in workplaces and may aid in controlling infection spread.
Subject(s)
COVID-19 , SARS-CoV-2 , Environmental Monitoring , Humans , Plants, Edible , PrevalenceABSTRACT
BACKGROUND: The Enterobacteriaceae and generic Escherichia coli are routinely enumerated in foods as part of product release criteria, or in the case of swabs, for environmental monitoring. OBJECTIVE: Microbiologique Microfilm™ EBEc is intended to provide a rapid and easy-to-use method for simultaneous enumeration of Enterobacteriaceae and E. coli on foods and environmental surfaces. Methods: This study evaluated the performance of Microfilm™ EBEc against ISO methods (ISO 21528-2:2017 for Enterobacteriaceae and ISO 16649-2: 2001 for E. coli) in 20 food matrixes and two environmental surfaces. Inclusivity, exclusivity, lot-to-lot reproducibility, ruggedness and stability studies were also performed on Microfilm™ EBEc. RESULTS: No significant differences and high correlation coefficients (R2) were observed between the Microfilm™ EBEc and the corresponding ISO methods in spiked food matrixes and environmental samples. Inclusivity studies showed expected results for all the E. coli and Enterobacteriaceae strains tested. In terms of exclusivity testing, all the strains tested failed to grow on Microfilm™ EBEc. A lot-to-lot study showed no significant differences in mean difference (log10) counts among the three lots of the Microfilm™ EBEc. Ruggedness studies showed no significant differences in mean difference (log10) counts at varying incubation temperatures and times. Stability studies on the Microfilm™ EBEc showed that it is stable at 2-25°C for 12 months, and at 45°C for 6 weeks. CONCLUSIONS: The results of this study indicate that the Microfilm™ EBEc is equivalent to the corresponding ISO methods for enumeration of Enterobacteriaceae and E. coli. Highlights: Microfilm™ EBEc offers a convenient and relatively fast test method for simultaneous enumeration of Enterobacteriaceae and E. coli in 24 h and has an advantage over the corresponding ISO methods that require two assays on the same sample for enumeration of Enterobacteriaceae and E. coli Gram-negative indicator groups.
