Microbiological survey and genomic analysis of Cronobacter sakazakii strains isolated from US households and retail foods.

Cronobacter species are opportunistic pathogens that are capable of causing morbidity and mortality, particularly in infants. Although the transmission dynamics involved in Cronobacter infections remain largely unknown, contaminated powdered infant formula (PIF) has been linked to 30% of Cronobacter sakazakii cases involving invasive illness in infants. As several lines of evidence have implicated the domestic environment in PIF contamination, we undertook a microbiological survey of homes (N = 263) across the US. Cronobacter spp. and C. sakazakii were isolated from 36.1% and 24.7% of US homes, respectively, with higher recovery rates observed for floor and kitchen surfaces. Multi-locus sequence typing indicated that the dominant strain was C. sakazakii ST4, the sequence type most commonly associated with neonatal meningitis. For comparison purposes, retail foods (N = 4,009) were also surveyed, with the highest contamination frequencies (10.1%-26.3%) seen for nut products, seeds, and grains/baked goods/flours. The sequence type profile of isolates recovered from homes mirrored that of isolates recovered from retail foods, with increased representation of ST1, ST4, ST13, ST17, and ST40. Analysis of 386 whole genomic sequences revealed significant diversity. Redundancies were only observed for isolates recovered from within the same domicile, and there were no identical matches with sequences archived at the NCBI pathogen database. Genes coding for putative virulence and antibiotic resistance factors did not segregate with clinically significant sequence types. Collectively, these findings support the possibility that contamination events occurring within the home should not be overlooked as a contributor to community-onset Cronobacter infections. IMPORTANCE: Cronobacter sakazakii is an opportunistic pathogen that can cause significant morbidity and mortality in neonates. Its transmission dynamics are poorly understood, though powered infant formula (PIF) is thought to be the major transmission vehicle. How the PIF becomes contaminated remains unknown. Our survey shows that roughly 1/4 of US homes are contaminated with Cronobacter sakazakii, particularly in the kitchen setting. Our analyses suggest that the domestic environment may contribute to contamination of PIF and provides insights into mitigating the risk of transmission.

Comparison of Roka Atlas® System Performance and Health Canada Reference Method for Listeria Detection from Plastic, Sealed Concrete, and Stainless Steel Surface Samples.

BACKGROUND: There is a high demand in food industry and public health for rapid automated methods capable of high volume sample processing. OBJECTIVE: In an unpaired study Roka Atlas® System performance was compared with Health Canada reference method MFHPB-30 for Listeria spp. (LSP Roka assay) and Listeria monocytogenes (LmG2 Roka Assay) detection on plastic (PL), sealed concrete (SC), and stainless steel (SS) surfaces (45 samples each per candidate or reference method). METHODS: Seeking shorter enrichment time for the candidate method, R2 medium pre-enrichment for 14, 16, and 24 h at 35 °C was combined with the Roka assay. Listeria welshimeri, L. innocua, and L. monocytogenes were employed to individually inoculate each of the three surfaces, with two competing microorganisms within the 10-100 fold higher concentration range. RESULTS: False negative, false positive, sensitivity and specificity were 0, 0, 100, and 100%, respectively, for the plastic, sealed concrete, and stainless steel surfaces, regardless of inoculation level (high, low, and uninoculated) and enrichment time. Candidate method detected 10, 7 and 9 true positives, versus 10, 6 and 10 by the reference method in individually inoculated SS, PL and SC, respectively. CONCLUSION: Probability of detection for all the three surfaces for the Roka Atlas® System was comparable to the reference method, in this unpaired study. HIGHLIGHTS: The Roka Atlas® System detected targets after as little as 14 h enrichment.Surface type did not negatively affect assay sensitivity or specificity.The Roka Atlas® System was comparable to the reference method.

Prevalence of SARS-CoV-2 Contamination on Food Plant Surfaces as Determined by Environmental Monitoring.

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.