Norovirus on planes

Human norovirus (HuNoV) is one of the leading causes of acute gastroenteritis globally. HuNoV outbreaks have been recently reported during air travels. Contaminated surfaces are known as a critical transmission route at various settings. The aim of this study was to provide key information about the survival and the decontamination of HuNoV on three commonly touched airplane cabin surfaces.

In this study, we monitored the survival of HuNoV on seat leather, plastic tray table, and seatbelt for 30 days, with and without additional organic load (simulated gastric fluid). The efficacy of two EPA registered anti-norovirus disinfectants were also evaluated. Results showed that HuNoV was detected at high titers (>4 log10 genomic copy number) for up to 30 days when additional organic load was present. Both tested disinfectants were found highly ineffective against HuNoV when the surface was soiled. The study showed that when the organic load was present, HuNoV was highly stable and resistant against disinfectants.

Findings from this study indicated that appropriate procedures should be developed by airline companies with the help of public health authorities to decrease passengers’ exposure risk to HuNoV.

Survival and inactivation of human norovirus GII.4 Sydney on commonly touched airplane cabin surfaces

Public Health 29 July 2020

Dorra Djebbi-Simmons, Mohammed Alhejaili, Marlene Janes, Joan King and Wenqing Xu*

DOI: 10.3934/publichealth.2020046

Floodwater, E. coli and leafy greens

The California Leafy Green Products Handler Marketing Agreement (LGMA) requires leafy green crops within 9 m of the edge of a flooded field not be harvested due to potential contamination (California Leafy Green Products Handler Marketing Board, Commodity Specific Flood Safety Guidelines for the Production and Harvest of Lettuce and Leafy Greens, 2012). Further, previously flooded soils should not be replanted for 60 days.

lettuceIn this study, the suitability of the LGMA metrics for farms in the Mid-Atlantic region of the United States was evaluated. The upper end of a spinach bed (in Beltsville, MD) established on a −5% grade was flooded with water containing 6 log CFU/ml Escherichia coli to model a worst-case scenario of bacterial movement through soil. Escherichia coli prevalence in soil and on foliar tissue was determined by most probable number (MPN) analysis at distances up to 9 m from the edge of the flood for 63 days. While E. coli was quickly detected at the 9-m distance within 1 day in the spring trial and within 3 days in the fall trial, no E. coli was detected on plants outside the flood zone after 14 days. On day 63 for the two trials, E. coli populations in the flood zone soil were higher in the fall than in the spring. Regression analysis predicted that the time required for a 3-log MPN/g (dry weight) decrease in E. coli populations inside the flood zone was within the 60-day LGMA guideline in the spring but would require 90 days in the fall. Overall, data suggest that the current guidelines should be revised to include considerations of field and weather conditions that may promote bacterial movement and survival.

Metrics proposed to prevent the harvest of leafy green crops exposed to floodwater contaminated with Escherichia coli

Appl. Environ. Microbiol. July 2016 vol. 82 no. 13 3746-3753, DOI: 10.1128/AEM.00052-16

Mary Theresa Callahan, Shirley A. Micallef, Manan Sharma, Patricia D. Millner, Robert L. Buchanan

It’s dry in here: Bugs on bathroom surfaces largely dormant

Human-associated bacteria dominate the built environment (BE)

Following decontamination of floors, toilet seats, and soap dispensers in four public restrooms, in situ bacterial communities were characterized hourly, daily, and weekly to determine their successional ecology. The viability of cultivable bacteria, following the removal of dispersal agents (humans), was also assessed hourly.

toilet_graffiti_620A late-successional community developed within 5 to 8 h on restroom floors and showed remarkable stability over weeks to months. Despite late-successional dominance by skin- and outdoor-associated bacteria, the most ubiquitous organisms were predominantly gut-associated taxa, which persisted following exclusion of humans. Staphylococcus represented the majority of the cultivable community, even after several hours of human exclusion. Methicillin-resistant  Staphylococcus aureus (MRSA)-associated virulence genes were found on floors but were not present in assembled Staphylococcus pan-genomes.

Viral abundances, which were predominantly enterophages, human papilloma virus, and herpes viruses, were significantly correlated with bacterial abundances and showed an unexpectedly low virus-to-bacterium ratio in surface-associated samples, suggesting that bacterial hosts are mostly dormant on BE surfaces.

Ecological succession and viability of human-associated microbiota on restroom surfaces

Applied and Environmental Microbiology, Volume 81, Issue 2, January 2015, Pages 765-773

S. Gibbons, T. Schwartz, J. Fouquier, M. Mitchell, N. Sangwan, J. Gilbert, and S. Kelley

Wyoming researchers discover substance that increases Listeria monocytogenes survival

University of Wyoming researchers have discovered a substance that greatly increases the survival of Listeria monocytogenes, a foodborne bacterial pathogen that contaminates processed meat and milk products, as well as fresh produce.

listeriaResearchers hope the discovery will lead to the development of techniques to better combat the pathogen and to improve food safety.

Mark Gomelsky, a professor in UW’s Department of Molecular Biology, and other researchers discovered and characterized a substance, called exopolysaccharide (EPS), that Listeria secretes on its cell surface under certain conditions. The EPS coats bacterial cells and makes them form aggregates or clumps, which are strongly protected from commonly used disinfectants and desiccation (extreme drying).

“We think that EPS plays a significant role in survival of Listeria in the environment, during food storage, processing and transportation,” Gomelsky says. “Listeria rarely causes serious disease in healthy individuals but, in immune-compromised people, elderly and pregnant women, it can be deadly, causing as much as 20 percent to 25 percent mortality.”

Gomelsky is a senior writer of a paper, titled “Cyclic di-GMP-Dependent Signaling Pathways in the Pathogenic Firmicute Listeria monocytogenes,” that was published in Public Library of Science (PLoS) Pathogens Thursday.