Modeling to reduce risks of Salmonella in alfalfa sprouts

We developed a risk assessment of human salmonellosis associated with consumption of alfalfa sprouts in the United States to evaluate the public health impact of applying treatments to seeds (0–5-log10 reduction in Salmonella) and testing spent irrigation water (SIW) during production.

The risk model considered variability and uncertainty in Salmonella contamination in seeds, Salmonella growth and spread during sprout production, sprout consumption, and Salmonella dose response.

Based on an estimated prevalence of 2.35% for 6.8 kg seed batches and without interventions, the model predicted 76,600 (95% confidence interval (CI) 15,400–248,000) cases/year. Risk reduction (by 5- to 7-fold) predicted from a 1-log10 seed treatment alone was comparable to SIW testing alone, and each additional 1-log10 seed treatment was predicted to provide a greater risk reduction than SIW testing. A 3-log10 or a 5-log10 seed treatment reduced the predicted cases/year to 139 (95% CI 33–448) or 1.4 (95% CI <1–4.5), respectively. Combined with SIW testing, a 3-log10 or 5-log10 seed treatment reduced the cases/year to 45 (95% CI 10–146) or <1 (95% CI <1–1.5), respectively. If the SIW coverage was less complete (i.e., less representative), a smaller risk reduction was predicted, e.g., a combined 3-log10 seed treatment and SIW testing with 20% coverage resulted in an estimated 92 (95% CI 22–298) cases/year.

Analysis of alternative scenarios using different assumptions for key model inputs showed that the predicted relative risk reductions are robust. This risk assessment provides a comprehensive approach for evaluating the public health impact of various interventions in a sprout production system.

Risk assessment of salmonellosis from consumption of alfalfa sprouts and evaluation of the public health impact of sprout seed treatment and spent irrigation water testing

January 2018, Risk Analysis

Yuhuan Chen, Regis Pouillot, Sofia Farakos, Steven Duret, Judith Spungen, Tong-Jen Fu, Fazila Shakir, Patricia Homola, Sherri Dennis, Jane Van Doren

DOI: 10.1111/risa.12964

http://onlinelibrary.wiley.com/doi/10.1111/risa.12964/epdf

26 sick: Multistate outbreak of Salmonella infections linked to Coconut Tree brand frozen shredded coconut

The U.S. Centers for Disease Control (CDC), public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) are investigating a multistate outbreak of Salmonella infections.

As of January 12, 2018, 25 people infected with the outbreak strains of Salmonella I 4,[5],12:b:- (24 people) or Salmonella Newport (1 person) have been reported from 9 states. One more ill person infected with the outbreak strain of Salmonella I 4,[5],12:b:- has been reported from Canada.

WGS showed that isolates from people infected with Salmonella I 4,[5],12:b:- are closely related genetically. This close genetic relationship means that people in this outbreak are more likely to share a common source of infection.

Illnesses started on dates ranging from May 11, 2017 to November 4, 2017. Ill people range in age from 1 year to 82, with a median age of 19. Among ill people, 19 (76%) are male. Six people (24%) report being hospitalized. No deaths have been reported.

Epidemiologic, laboratory, and traceback evidence indicates that Coconut Tree Brand frozen Shredded Coconut is the likely source of this multistate outbreak. This investigation is ongoing.

In interviews, ill people answered questions about the foods they ate and other exposures in the week before they became ill. Ten (63%) of 16 people interviewed reported eating or maybe eating coconut. Of these 10 people, 8 (80%) reported having an Asian-style dessert drink that contained frozen shredded coconut.

Throughout the outbreak investigation, state and local health officials have collected different food items from restaurants where ill people consumed Asian-style dessert drinks. In November 2017, laboratory testing of a sample from coconut milk made in one restaurant in New York did not identify the outbreak strain of Salmonella I 4,[5],12:b:-, but did identify a strain of SalmonellaNewport. This sample was from coconut milk made with Coconut Tree Brand frozen Shredded Coconut, as well as other ingredients. WGS showed that the Salmonella Newport isolated from the coconut milk was closely related genetically to a Salmonella Newport isolate from an ill person from Massachusetts who had consumed an Asian-style dessert drink.

In December 2017, officials in Massachusetts collected food items from a restaurant where that ill person had consumed Asian-style dessert drinks. One sample from frozen shredded coconut identified a strain of Salmonella that was new to the PulseNet database and has not been linked to any illnesses. This sample was from an unopened package of Coconut Tree Brand Frozen Shredded Coconut. As a result, on January 3, 2018, Evershing International Trading Company recalled all Coconut Tree Brand Frozen Shredded Coconut. The recalled product was packaged in 16-ounce plastic bags.

Officials in Massachusetts returned to the restaurant and collected more Coconut Tree Brand frozen Shredded Coconut in January 2018. On January 12, laboratory testing confirmed that samples from that frozen shredded coconut identified the outbreak strain of Salmonella I 4,[5],12:b:-. Laboratory testing of other samples identified several types of Salmonella bacteria, including Salmonella Javiana, Salmonella Rissen, and Salmonella Thompson. These samples were from unopened packages of Coconut Tree Brand Frozen Shredded Coconut sold before January 3, 2018. CDC is reviewing the PulseNet database to determine if the other Salmonella isolates from the frozen shredded coconut are linked to any illnesses.

Frozen shredded coconut can last for several months if kept frozen and may still be in retail stores or in people’s homes. CDC recommends that retailers not sell, restaurants not serve, and consumers not eat recalled Coconut Tree Brand frozen Shredded Coconut.

Salmonella may have caused a massive Aztec epidemic, study finds

Rebecca Hersher of NPR reports that in 1545, people in the Mexican highlands starting dying in enormous numbers. People infected with the disease bled and vomited before they died. Many had red spots on their skin.

It was one of the most devastating epidemics in human history. The 1545 outbreak, and a second wave in 1576, killed an estimated 7 million to 17 million people and contributed to the destruction of the Aztec Empire.

But identifying the pathogen responsible for the carnage has been difficult for scientists because infectious diseases leave behind very little archaeological evidence.

“There have been different schools of thought on what this disease was. Could it have been plague? Could it have been typhoid fever? Could it have been a litany of other diseases?” says Kirsten Bos, a molecular paleopathologist at the Max Planck Institute in Germany, and an author of a new study published Monday in Nature Ecology and Evolution.

The study analyzes DNA from the teeth of 10 people who died during the epidemic and pinpoints a possible culprit: a type of salmonella that causes a deadly fever.

A new algorithm allowed Bos and her team to identify fragments of ancient salmonella DNA with extreme specificity.

“It was an analytical technique that was really the game-changer for us,” Bos explains. While scientists have been able to extract ancient DNA from bones and other tissue, until recently it was impossible to compare that extracted DNA to a wide variety of potential matches.

But a new computer program called MALT allowed them to do just that. “The major advancement was this algorithm,” Bos says. “It offers a method of analyzing many, many, many small DNA fragments that we get, and actually identifying, by species name, the bacteria that are represented.”

Bos and her team used MALT to match up the DNA fragments extracted from teeth of epidemic victims with a database of known pathogens. The program didn’t entire save them from mind-numbing work — at one point PhD student and study author Ashild Vagene had to go through the results of the program by hand.

In the end, they found evidence of the deadly Salmonella enterica Paratyphi C bacteria.

The study does not pinpoint the source of the bacteria, which is an area of great interest for biologists and archaeologists alike. The authors note that many epidemics of the period are believed to originate with European invaders who arrived in the region in the early part of the 16th century, but the new research doesn’t present biological evidence for or against that.

Salmonella enterica gemones from victims of a major sixteenth-century epidemic in Mexico

Nature Ecology and Evolution, Published online 15 January 2018, Åshild J. VågeneAlexander HerbigMichael G. CampanaNelly M. Robles GarcíaChristina WarinnerSusanna SabinMaria A. SpyrouAida Andrades ValtueñaDaniel HusonNoreen TurossKirsten I. Bos & Johannes Krause, doi:10.1038/s41559-017-0446-6

https://www.nature.com/articles/s41559-017-0446-6

Indigenous populations of the Americas experienced high mortality rates during the early contact period as a result of infectious diseases, many of which were introduced by Europeans. Most of the pathogenic agents that caused these outbreaks remain unknown.

Through the introduction of a new metagenomic analysis tool called MALT, applied here to search for traces of ancient pathogen DNA, we were able to identify Salmonella enterica in individuals buried in an early contact era epidemic cemetery at Teposcolula-Yucundaa, Oaxaca in southern Mexico. This cemetery is linked, based on historical and archaeological evidence, to the 1545–1550 CE epidemic that affected large parts of Mexico. Locally, this epidemic was known as ‘cocoliztli’, the pathogenic cause of which has been debated for more than a century.

Here, we present genome-wide data from ten individuals for Salmonella enterica subsp. enterica serovar Paratyphi C, a bacterial cause of enteric fever. We propose that S. Paratyphi C be considered a strong candidate for the epidemic population decline during the 1545 cocoliztli outbreak at Teposcolula-Yucundaa.

36 sick: Lactalis offers salmonella compensation, French government says probe continues

We’re in New Caledonia for Amy to do some French professoring stuff, with the Calgary-Carolina hockey game on in the background on a sports channel from France.

I went for a walk along the ocean this morning, sans Ted, which is the extent of my French.

While I’m surrounded by the beauty of this Pacific island, the Lactalis mess in France continues a downslide into parody (except for the sick kids and their families).

According to Reuters, France welcomed dairy group Lactalis’ pledge to compensate victims of a Salmonella contamination in its baby milk on Sunday, but said a judicial investigation to determine who was responsible would continue.

Lactalis Chief Executive Emmanuel Besnier told the weekly Journal du Dimanche his family company, one of the world’s biggest dairies, would “pay damages to every family which has suffered a prejudice.”

Is prejudice French for barfing?

Salmonella infections can be life-threatening and the families of three dozen children who have fallen sick in France as a result of the contaminated baby milk have announced a raft of lawsuits.

Besnier’s promise came two days after Lactalis widened a product recall to cover all infant formula made at its Craon plan, regardless of the manufacture date, in a bid to contain the fallout from a health scare that risks damaging France’s strategic agribusiness in overseas markets.

“Paying compensation is good, but money cannot buy everything,” government spokesman Benjamin Griveaux said in an interview on BFM TV.

The health scare intensified last week after France’s biggest retailers including Carrefour, Auchan and Leclerc admitted products recalled in December had still found their way onto shelves.

“It is the job of the investigation to determine where failings occurred and who is to blame,” Griveaux said, adding that “responsibilities were shared.”

Implementing the global recall will be challenging. Privately owned Lactalis, one of the world’s biggest dairies, exports its baby food products to 83 countries across Europe, Africa and Asia.

The recall involves some 12 million tins of baby milk.

“It’s not easy to evaluate the number of items that need to be returned because we don’t know what’s been consumed already,” Besnier said in a rare newspaper interview published on Sunday.

Friday’s recall was the third in a month and Lactalis has come under fire for its clumsy response. Besnier also told the French weekly that the company had acted as quickly and efficiently as possible and denied slowing the process to curb losses.

Besnier has also been criticized for failing to speak out publicly during the salmonella scare.

While his family are France’s 11th wealthiest, according to a 2017 ranking by Challenges magazine, the dairy tycoon has long shunned the public limelight and schmoozing with politicians.

His workers nickname him the “invisible man.”

“We’re a discreet business. In this region there is a mentality of ‘work first, speak later,” he said. But he acknowledged lessons had been learned during the past few weeks.

Lactalis has become an industry giant, with annual sales of 17 billion euros ($20.73 billion) and 18,900 employees across some 40 countries.


 

Looks like Chile has an egg problem: 174 sick with Salmonella linked to homemade mayo

The Bío Bío Department of Health has confirmed 174 cases of salmonellosis in people who consumed homemade mayonnaise in the local “Dulce y Salado” (“Sweet and Salty”) of Lota.

Among those affected are 25 hospitalized for severe dehydration, including a pregnant woman. There are also sufferers of all ages, such as a one-year-old baby and up to an adult older than 91.
According to the health authority, the number of patients should not increase substantially due to the number of days that have passed since the closure of the premises, on Jan. 3. 2018. Now it is expected that laboratories in Santiago will determine the serotype of the strain, which may allow them to fully define whether the raw egg was responsible for this outbreak.

 

Whole genone sequencing fingers ham as source of Salmonella outbreak in Netherlands

In January 2017, an increase in reported Salmonella enterica serotype Bovismorbificans cases in the Netherlands was observed since October 2016. We implemented a case–control study to identify the source, including all cases after December 2016.

Adjusted odds ratios were calculated using logistic regression analysis. We traced back the distribution chain of suspected food items and sampled them for microbiological analysis. Human and food isolates were sequenced using whole genome sequencing (WGS).

From October 2016 to March 2017, 54 S. Bovismorbificans cases were identified. Sequencing indicated that all were infected with identical strains. Twenty-four cases and 37 controls participated in the study. Cases were more likely to have consumed ham products than controls (aOR = 13; 95% CI: 2.0–77) and to have shopped at a supermarket chain (aOR = 7; 95% CI: 1.3–38).

Trace-back investigations led to a Belgian meat processor: one retail ham sample originating from this processor tested positive for S. Bovismorbificans and matched the outbreak strain by WGS. All ham products related to the same batch were removed from the market to prevent further cases. This investigation illustrates the importance of laboratory surveillance for all Salmonella serotypes and the usefulness of WGS in an outbreak investigation.

Outbreak of Salmonella Bovismorbificans associated with the consumption of uncooked ham products, the Netherlands, 2016 to 2017

Eurosurveillance; Volume 23; Issue 1; 4 January 2018

Brandwagt Diederik, van den Wijngaard Cees, Tulen Anna Dolores, Mulder Annemieke Christine, Hofhuis Agnetha, Jacobs Rianne, Heck Max, Verbruggen Anjo, van den Kerkhof Hans, Slegers-Fitz-James Ife, Mughini-Gras Lapo, Franz Eelco

http://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2018.23.1.17-00335

It’s all the rage: Could high-pressure processing be risky?

High-pressure processing is a non-thermal method of food preservation that uses pressure to inactivate microorganisms. To ensure the effective validation of process parameters, it is important that the design of challenge protocols consider the potential for resistance in a particular species.

Herein, the responses of 99 diverse Salmonella enterica strains to high pressure are reported. Members of this population belonged to 24 serovars and were isolated from various Canadian sources over a period of 26 years. When cells were exposed to 600 MPa for 3 min, the average reduction in cell numbers for this population was 5.6 log10 CFU/ml, with a range of 0.9 log10 CFU/ml to 6 log10 CFU/ml. Eleven strains, from 5 serovars, with variable levels of pressure resistance were selected for further study. The membrane characteristics (propidium iodide uptake during and after pressure treatment, sensitivity to membrane-active agents, and membrane fatty acid composition) and responses to stressors (heat, nutrient deprivation, desiccation, and acid) for this panel suggested potential roles for the cell membrane and the RpoS regulon in mediating pressure resistance in S. enterica. The data indicate heterogeneous and multifactorial responses to high pressure that cannot be predicted for individual S. enterica strains.

The responses of foodborne pathogens to increasingly popular minimal food decontamination methods are not understood and therefore are difficult to predict. This report shows that the responses of Salmonella entericastrains to high-pressure processing are diverse. The magnitude of inactivation does not depend on how closely related the strains are or where they were isolated. Moreover, strains that are resistant to high pressure do not behave similarly to other stresses, suggesting that more than one mechanism might be responsible for resistance to high pressure and the mechanisms used may vary from one strain to another.

Population-wide survey of Salmonella enterica response to high-pressure processing reveals a diversity of responses and tolerance mechanisms

Applied and Environmental Microbiology, Volume 8, Number 2, January 2018

Sandeep Tamber

http://aem.asm.org/content/84/2/e01673-17.abstract?etoc

 

Does your stomach hurt? Maybe it’s because of a lot of food poisoning

Foodborne infections represent a serious and increasing human health problem while at the same time the incidence and prevalence of colitis and the inflammatory bowel diseases (IBDs) are increasing. The origins of these life-threatening syndromes predominantly include environmental factors deduced from studies of genetic twins and other human populations. Pathogen infection has been postulated as a possible environmental trigger of chronic intestinal inflammation and colitis. The Salmonella bacterial pathogen, for example, is widespread throughout the environment and remains a leading cause of human foodborne illness and disease. Salmonella infection can occur by the ingestion of contaminated food products often resulting in acute but temporary intestinal discomfort and dysfunction.

Possible links between pathogen infections and chronic intestinal inflammation are under increased study. Bacterial infections have been associated with seasonal increases in hospital admissions diagnosing intestinal inflammation and the IBDs. We considered that common repeated infections such as may occur in human food poisoning by Salmonella might be involved in triggering chronic intestinal inflammation. Such infections could be relatively mild, causing few symptoms that go unreported and disappear without clinical intervention, making it possible that there is currently an underappreciation of the numbers of infections occurring among individuals over a life span. We investigated whether low-titer and nonlethal Salmonella infections, designed to model repeated episodes of human food poisoning, may lead to chronic intestinal inflammation and colitis. If so, such a mechanism might be responsible for triggering human inflammatory syndromes including colitis and IBDs.

We developed and characterized a model of human food poisoning in the mouse using recurrent low-dose and nonlethal gastrointestinal infections of a virulent Salmonella isolate. We observed that repeated exposure induced inflammation of intestinal tissues, especially the colon. Although the host effectively cleared the pathogen weeks before reinfection, inflammation and intestinal tissue damage progressively increased in severity with additional infections. In addition, after the cessation of additional infections, inflammation and tissue damage failed to subside and persisted for months throughout the duration of study. We have identified the disease mechanism to be an acquired deficiency of intestinal alkaline phosphatase (IAP), an enzyme produced by enterocytes of the duodenum of the small intestine. IAP dephosphorylates and detoxifies the lipopolysaccharide (LPS) endotoxin produced by commensal microbiota of the host. Salmonella infection induced endogenous neuraminidase (Neu) activity among enterocytes of the duodenum by a Toll-like receptor 4 (TLR4)–dependent mechanism. This elevation of Neu activity accelerated the molecular aging and turnover of IAP, causing IAP deficiency in the colon. IAP deficiency led to elevated levels of LPS-phosphate that provoked TLR4-dependent inflammation. IAP augmentation or neuraminidase inhibition using a marketed antiviral neuraminidase inhibitor were similarly effective at preventing the accumulation of LPS-phosphate and the onset of disease.

We have discovered an environmental and pathogenic origin of chronic intestinal inflammation using a model of recurrent human food poisoning. We further show that this disease can be prevented by either IAP augmentation or Neu inhibition, both of which may represent prophylactic and therapeutic approaches to human colitis and the IBDs.

Recurrent infection progressively disables host protection against intestinal inflammation

Science, vol. 358, issue 6370, Won Ho Yang, Douglas M. Heithoff, Peter V. Aziz, Markus Sperandio, Victor Nizet, Michael J. Maha, DOI: 10.1126/science.aao5610

http://science.sciencemag.org/content/358/6370/eaao5610

Yup, they get into produce seeds, especially sprouts: Salmonella and E. coli internalization

Vegetable seeds contaminated with bacterial pathogens have been linked to fresh-produce-associated outbreaks of gastrointestinal infections. This study was undertaken to observe the physiological behavior of Salmonella enterica and enterohemorrhagic Escherichia coli (EHEC) cells artificially internalized into vegetable seeds during the germination process.

Surface-decontaminated seeds of alfalfa, fenugreek, lettuce, and tomato were vacuum-infiltrated with four individual strains of Salmonella or EHEC. Contaminated seeds were germinated at 25°C for 9 days, and different sprout/seedling tissues were microbiologically analyzed every other day. The internalization of Salmonella and EHEC cells into vegetable seeds was confirmed by the absence of pathogens in seed-rinsing water and the presence of pathogens in seed homogenates after post-internalization seed surface decontamination.

Results show that 317 (62%) and 343 (67%) of the 512 collected sprout/seedling tissue samples were positive for Salmonella and EHEC, respectively. The average Salmonella populations were significantly larger (P < 0.05) than the EHEC populations. Significantly larger Salmonella populations were recovered from the cotyledon and seed coat tissues, followed by the root tissues, but the mean EHEC populations from all sampled tissue sections were statistically similar, except in pre-germinated seeds. Three Salmonella and two EHEC strains had significantly larger cell populations on sprout/seedling tissues than other strains used in the study.

Salmonella and EHEC populations from fenugreek and alfalfa tissues were significantly larger than those from tomato and lettuce tissues. The study showed the fate of internalized human pathogens on germinating vegetable seeds and sprout/seedling tissues and emphasized the importance of using pathogen-free seeds for sprout production.

Fate of Salmonella enterica and Enterohemorrhagic Escherichia coli cells artificially internalized into vegetable seeds during germination

Appl. Environ. Microbiol. January 2018 84:e01888-17; Accepted manuscript posted online 27 October 2017, doi:10.1128/AEM.01888-17

Da Liu, Yue Cui, Ronald Walcott and Jinru Chen

http://aem.asm.org/content/84/1/e01888-17.abstract?etoc

 

 

Audits and inspections are never enough: French inspectors missed Salmonella at baby milk plant

French food safety inspectors failed to detect salmonella contamination at a plant belonging to dairy giant Lactalis, three months before the company carried out a major recall of baby milk, a report said Wednesday.

Lactalis, one of the world’s largest producers of dairy products, discovered the bacteria at its factory in Craon, northwest France, during tests in August and November.

It did not however report the find to the authorities.

Officials from the food safety department carried out a routine inspection of the site in September and gave it a clean bill of health, the Canard Enchaine investigative weekly reported.

It was only three months later, after around 30 infants being fed Lactalis powdered milk fell sick, that the health ministry sounded the alarm.

Officials from the national anti-fraud bureau swooped on the site on December 2 and found the assembly line where liquid milk is transformed into formula to be contaminated.

Lactalis issued two major recalls covering all production from the site from February 15, blaming the contamination on renovation work.

The plant has been at a standstill since December 8.

Lactalis is under investigation over the affair.

It could face charges of causing involuntary injuries and endangering the lives of others.

Market food safety at retail so consumers can choose.

Audits and inspections are never enough: A critique to enhance food safety

30.aug.12

Food Control

D.A. Powell, S. Erdozain, C. Dodd, R. Costa, K. Morley, B.J. Chapman

http://www.sciencedirect.com/science/article/pii/S0956713512004409?v=s5

Internal and external food safety audits are conducted to assess the safety and quality of food including on-farm production, manufacturing practices, sanitation, and hygiene. Some auditors are direct stakeholders that are employed by food establishments to conduct internal audits, while other auditors may represent the interests of a second-party purchaser or a third-party auditing agency. Some buyers conduct their own audits or additional testing, while some buyers trust the results of third-party audits or inspections. Third-party auditors, however, use various food safety audit standards and most do not have a vested interest in the products being sold. Audits are conducted under a proprietary standard, while food safety inspections are generally conducted within a legal framework. There have been many foodborne illness outbreaks linked to food processors that have passed third-party audits and inspections, raising questions about the utility of both. Supporters argue third-party audits are a way to ensure food safety in an era of dwindling economic resources. Critics contend that while external audits and inspections can be a valuable tool to help ensure safe food, such activities represent only a snapshot in time. This paper identifies limitations of food safety inspections and audits and provides recommendations for strengthening the system, based on developing a strong food safety culture, including risk-based verification steps, throughout the food safety system.