19 sickened: Temperatures matter; C. perfringens outbreak at a catered lunch Connecticut, 2016

The U.S. Centers for Disease Control reports in September 2016, the Connecticut Department of Public Health was notified of a cluster of gastrointestinal illnesses among persons who shared a catered lunch.

The Connecticut Department of Public Health worked with the local health department to investigate the outbreak and recommend control measures. Information about symptoms and foods eaten was gathered using an online survey. A case was defined as the onset of abdominal pain or diarrhea in a lunch attendee <24 hours after the lunch. Risk ratios (RRs), 95% confidence intervals (CIs), and Fisher’s exact p-values were calculated for all food and beverages consumed. Associations of food exposures with illness were considered statistically significant at p<0.05. Among approximately 50 attendees, 30 (60%) completed the survey; 19 (63%) respondents met the case definition. The majority of commonly reported symptoms included diarrhea (17 of 18), abdominal pain (15 of 16), and headache (7 of 15).

The median interval from lunch to illness onset was 5.3 hours (range = 0.4–15.5 hours) for any symptom and 7 hours (range = 2.5–13 hours) for diarrhea. Analysis of food exposures reported by 16 ill and 10 well respondents (four respondents did not provide food exposure information) found illness to be associated with the beef dish (RR = undefined; CI = 1.06–∞; p = 0.046) (Table). All 16 ill respondents reported eating the beef. Coffee was also associated with illness; however, all 13 coffee drinkers who became ill also ate the beef. Eating cake approached significance (p = 0.051); all 10 cake eaters who became ill also ate the beef.The caterer had begun preparing all dishes the day before the lunch. Meats were partially cooked and then marinated in the refrigerator overnight. In the morning, they were sautéed 2 hours before lunch. Inspection of the facility found the limited refrigerator space to be full of stacked containers that were completely filled with cooked food, disposable gloves that appeared to have been washed for reuse, and a porous wooden chopping block.

The caterer’s four food workers reported no recent illness. Stool specimens from the food workers and from four ill attendees all tested negative for norovirus, Campylobacter, Escherichia coli O157, Salmonella, and Shigella at the Connecticut State Public Health Laboratory. All eight specimens were sent to the Minnesota Department of Health Public Health Laboratory, where additional testing was available. Two specimens from food workers were positive for enterotoxigenic Escherichia coli by polymerase chain reaction, but no enterotoxigenic E. coli colonies were isolated. Seven specimens (four from food workers and three from attendees) were culture-positive for Clostridium perfringens, and specimens from all attendees contained C. perfringens enterotoxin. Pulsed-field gel electrophoresis of 29 C. perfringens isolates from the culture-positive specimens found no matches among attendee isolates, but demonstrated a single matching pattern between two food worker specimens. No leftover food items were available for testing.

C. perfringens, a gram-positive, rod-shaped bacterium, forms spores allowing survival at normal cooking temperatures and germination during slow cooling or storage at ambient temperature (1). Diarrhea and other gastrointestinal symptoms are caused by C. perfringens enterotoxin production in the intestines. Vomiting is rare and illness is usually self-limited, although type C strains can cause necrotizing enteritis (1).

Symptoms reported were consistent with C. perfringens infection, with a predominance of diarrhea, and median diarrhea onset time was at the lower end of the typical C. perfringens incubation period (6–24 hours) (1). C. perfringens enterotoxin detection in the stool of two or more ill persons confirms C. perfringens as the outbreak etiology (2). Both C. perfringens and enterotoxigenic E. coli can colonize asymptomatic persons (3,4), which might explain the presence of these pathogens in the stools of asymptomatic food workers. Pulsed-field gel electrophoresis did not identify the C. perfringens strain responsible for the outbreak, but findings add to the evidence for a wide variety of C. perfringens strains, not all producing C. perfringens enterotoxin (5).

C. perfringens outbreaks are typically associated with improper cooling or inadequate reheating of contaminated meats (1), which might have occurred with the beef dish. The restaurant was advised about the need for adequate refrigeration and best practices for cooling foods, including using stainless steel rather than plastic containers, avoiding filling containers to depths exceeding two inches, avoiding stacking containers, and ventilating hot food. Upon follow-up inspection, staff members discarded disposable gloves after one use, used only food-grade cutting boards, and maintained proper food temperatures for hot holding, cold holding, cooling, and reheating, as outlined in the Food and Drug Administration Food Code.

An estimated 1 million illnesses in the United States each year are attributable to C. perfringens, but fewer than 1,200 illnesses are reported annually with C. perfringens outbreaks (6). C. perfringens testing is not routine for foodborne outbreaks; even if testing is unavailable, C. perfringens should be considered when improper cooling, inadequate reheating, and improper temperature maintenance of meat are identified.

I don’t see color, it doesn’t matter: UK hamburger edition

Don’t burger up your bank holiday.

Get it? Don’t bugger it up? Burger it up?

barfblog.Stick It InThose bureaucrats at UK’s Food Standards Agency are really yukking it up, focused on stupid jokes rather than evidence-based communications.

FSA has long been in its own undersirable class when talking about food safety risks, and class is so very important to the Brits.

FSA is great is talking at people rather than talking with people (a huge difference, like educating versus providing information).

FSA’s idea of risk communication is to commission a meaningless survey – people lie, especially about food and drink – which found that despite 71% of people stating that they are concerned about food poisoning, over a third (36%) of Brits would eat a burger that isn’t fully cooked through. More than one in 10 said that they actually prefer burgers cooked this way.  When cooking them at home 81% of those admit to undercooking them. So we at the FSA are encouraging all those who are getting their barbecues out this weekend to ensure they cook their burgers all the way through – until steaming hot throughout, there’s no pink meat in the middle and the juices run clear.

Those scientifically meanginless terms – steaming hot, no pink – have featured prominently in FSA foodsafetytalk for years, with steaming hot replacing piping hot.

Lead FSA policy thingy said something that is not worth repeating because it ignores the risks associated with needle-tenderized steaks.

And we’ve been over this so many times before.

The BBC repeated the advice verbatium in its latest version of PR blowjobs rather than something resembling journalism.

Use a thermometer and stick it in.

And now this.


It ain’t happening at retail: Cut cantaloupe needs to be stored at 4C to control Listeria growth

Cantaloupes, marketed as “Rocky Ford,” were implicated in the U.S. multistate outbreak of listeriosis in 2011, which caused multiple fatalities. Listeria monocytogenes can survive on whole cantaloupes and can be transferred to the flesh of melons.

fresh-cut.cantaloupeThe growth of L. monocytogenes on fresh-cut “Athena” and “Rocky Ford” cantaloupe cultivars during refrigerated storage was evaluated. Fresh-cut cubes (16.4 cm3) from field-grown cantaloupes were each inoculated with 5 log10 CFU/mL of a multi-strain mixture of L. monocytogenes and stored at 4°C or 10°C. Inoculated fresh-cut cubes were also: (1) continuously stored at 4°C for 3 days; (2) temperature-abused (TA: 25°C for 4 h) on day 0; or (3) stored at 4°C for 24 h, exposed to TA on day 1, and subsequently stored at 4°C until day 3. L. monocytogenes populations on fresh-cut melons continuously stored at 4°C or 10°C were enumerated on selected days for up to 15 days and after each TA event. Brix values for each cantaloupe variety were determined. L. monocytogenes populations on fresh-cut cantaloupe cubes stored at 4°C increased by 1.0 and 3.0 log10 CFU/cube by day 7 and 15, respectively, whereas those stored at 10°C increased by 3.0 log10 CFU/cube by day 7.

Populations of L. monocytogenes on fresh-cut cantaloupes stored at 10°C were significantly (p < 0.05) greater than those stored at 4°C during the study. L. monocytogenes showed similar growth on fresh-cut “Athena” and “Rocky Ford” cubes, even though “Athena” cubes had significantly higher Brix values than the “Rocky Ford” fruit.

L. monocytogenes populations on fresh-cut cantaloupes exposed to TA on day 1 and then refrigerated were significantly greater (0.74 log10 CFU) than those stored continuously at 4°C for 3 days. Storage at 10°C or exposure to TA events promoted growth of L. monocytogenes on fresh-cut cantaloupe during refrigerated storage.

Survival and growth of Listeria monocytogenes on fresh-cut “Athena” and “Rocky Ford” cantaloupes during storage at 4°C and 10°C

Nyarko Esmond, Kniel Kalmia E., Reynnells Russell, East Cheryl, Handy Eric T., Luo Yaguang, Millner Patricia D., and Sharma Manan. Foodborne Pathogens and Disease. August 2016, ahead of print. doi:10.1089/fpd.2016.2160.


Safety of sun tea

Nancy Haberstich, creator and founder of Nanobugs Inc. writes in the Lincoln Journal Star that the appeal of sun tea is the ease at which you can make it — pop a bunch of tea bags in a big jar of water and set it in the sun.

Sun-tea-in-mason-jarsHowever, sun tea does come with its risks.

Microbes can easily contaminate tea leaves. When added to water, these microbes can be revived and start multiplying — especially if they sit in warmer temperatures of 40 to 140 degrees.

Tea made with the sun’s rays will not get hotter than 130 degrees, Haberstich said. The caffeine in black tea will help prevent some bugs from flourishing for a few hours, but its effects won’t last beyond that. Herbal teas are an even worse bet for brewing in sunlight because they lack caffeine.

For safer iced tea, boil water and pour it over tea bags or tea leaves. Steep to desired concentration, then add ice and serve. Iced tea makers are also safe alternative, if they heat water to 195 degrees.

A new trend is the “cold brew” method — which is safe as the tea or coffee is “brewed” overnight in a refrigerator (which is colder than 40 degrees).

RTE salad storage temps should be reduced in Sweden

Prepacked ready-to-eat mixed ingredient salads (RTE salads) are readily available whole meals that include a variety of ingredients such as raw vegetables, cooked meat, and pasta.

rte.salad.swedenAs part of a trend toward healthy convenience foods, RTE salads have become an increasingly popular product among consumers. However, data on the incidence of foodborne pathogens in RTE salads are scarce.

In this study, the microbiological safety of 141 RTE salads containing chicken, ham, or smoked salmon was investigated. Salad samples were collected at retail and analyzed using standard methods for Listeria monocytogenes, Shiga toxin–producing Escherichia coli (STEC), pathogenic Yersinia enterocolitica, Salmonella, and Campylobacter spp.L. monocytogenes was isolated from two (1.4%) of the RTE salad samples.

Seven (5.0%) of the samples were positive for the ail gene (present in all human pathogenic Y. enterocolitica isolates) and three (2.1%) of the samples were positive for the Shiga toxin genes stx 1 and/or stx 2. However, no strains of pathogenic Y.enterocolitica or STEC were isolated.

Thus, pathogens were found or suspected in almost 1 of 10 RTE salads investigated, and pathogenic bacteria probably are present in various RTE salads from retail premises in Sweden.

Because RTE salads are intended to be consumed without heat treatment, control of the ingredients and production hygiene is essential to maintain consumer safety. The recommended maximum storage temperature for RTE salads varies among countries but can be up to 8°C (e.g., in Sweden). Even during a short shelf life (3 to 5 days), storage at 8°C can enable growth of psychrotrophs such as L. monocytogenes and Y. enterocolitica. The maximum storage temperature should therefore be reduced.

Foodborne bacterial pathogens in retail prepacked ready-to-eat mixed ingredient salads

Journal of Food Protection®, Number 6, June 2016, pp. 896-1055, pp. 978-985(8)

Söderqvist, Karin; Thisted Lambertz, Susanne; Vågsholm, Ivar; Boqvist, Sofia


Burgers may need higher cooking temperature to be safe from E. coli

Food safety friend Lynn McMullen at the University of Alberta, and others have found that cooking ground beef at 71C — the level of heat long advised by Health Canada — does not always eliminate all the strains of Escherichia coli.

mcmullen.e.coli.hamburger“We’ve been hammering consumers for years to cook chicken properly, to handle it properly, and to do the same with ground beef but still we seem to have these outbreaks of E. coli (attributed to hamburgers),” said food microbiologist McMullen.

“Does this explain why? It might.”

McMullen, fellow food microbiologist Michael Gänzle, and several graduate students, first became aware of the inconsistent behaviour of E. coli eight years ago.

For decades, scientific papers about the thermal killing of microorganisms have noted that there were sometimes survivors. But little attention was paid to that information until 2008, when McMullen and Gänzle assigned a student to look for differences in thermal survival amongst organisms in a large collection of E. coli from beef, which the U of A happens to house.

The first student, Elena Dlusskaya, showed that one organism had survived for 70 minutes at 60C. Both professors felt her study must be flawed, because most E. coli are killed just a few seconds after such heat application. Repeating her experiments twice produced the same odd results.

Then Dlusskaya compared her cultures to those from other labs, which already had published survival values. Again, she found that some of the U of A’s cultures were behaving differently.

“These organisms aren’t supposed to survive, but every once in a while they do,” said McMullen. “So we decided to find out why. We looked at the genomes to see what was different.”

Working with postdoctoral fellow Ryan Mercer, they discovered a suite of 16 genes that are found only in the highly heat-resistant strains of E. coli under wet conditions (i.e. fresh meat). This genomic grouping is called the locus of heat resistance, or LHR.

Hunting through the genome databases for LHR, they saw that it exists in about two per cent of all E. coli in the databases and is present in both the harmless and pathogenic strains.

barfblog.Stick It In“If it’s in two per cent of all E. coli, and in pathogenic E.coli, there’s the potential that a pathogen could survive the standard cooking protocols for ground beef. It could mean we have to change the guidelines for cooking meat, because 71C may not be enough.”

Salt also makes E. coli bacteria heat resistant, though McMullen and the other researchers don’t know why.

Though McMullen and the other researchers haven’t discovered what temperature will ultimately kill all E. coli, McMullen recommended using a thermometer and cooking meat at 71 C to 73 C. “It doesn’t matter when you’re grilling any ground meat, you should be using a thermometer.”

Genetic determinants of heat resistance in Escherichia coli

Front Microbiol. 2015; 6: 932.

Published online 2015 Sep 9. doi:  10.3389/fmicb.2015.00932

Ryan G. Mercer, Jinshui Zheng, Rigoberto Garcia-Hernandez, Lifang Ruan, Michael G. Gänzle, and Lynn M. McMullen


Escherichia coli AW1.7 is a heat resistant food isolate and the occurrence of pathogenic strains with comparable heat resistance may pose a risk to food safety. To identify the genetic determinants of heat resistance, 29 strains of E. coli that differed in their of heat resistance were analyzed by comparative genomics. Strains were classified as highly heat resistant strains, exhibiting a D60-value of more than 6 min; moderately heat resistant strains, exhibiting a D60-value of more than 1 min; or as heat sensitive. A ~14 kb genomic island containing 16 predicted open reading frames encoding putative heat shock proteins and proteases was identified only in highly heat resistant strains. The genomic island was termed the locus of heat resistance (LHR). This putative operon is flanked by mobile elements and possesses >99% sequence identity to genomic islands contributing to heat resistance in Cronobacter sakazakii and Klebsiella pneumoniae. An additional 41 LHR sequences with >87% sequence identity were identified in 11 different species of β- and γ-proteobacteria. Cloning of the full length LHR conferred high heat resistance to the heat sensitive E. coli AW1.7ΔpHR1 and DH5α. The presence of the LHR correlates perfectly to heat resistance in several species of Enterobacteriaceae and occurs at a frequency of 2% of all E. coli genomes, including pathogenic strains. This study suggests the LHR has been laterally exchanged among the β- and γ-proteobacteria and is a reliable indicator of high heat resistance in E. coli.

Temperature still matters: Spike in C. perfringens linked to UK aged homes

An anecdotal increase in C. perfringens outbreaks was observed in the North East of England during 2012–2014. We describe findings of investigations in order to further understanding of the epidemiology of these outbreaks and inform control measures.

clostridiumperfringens_c200pxAll culture-positive (>105 c.f.u./g) outbreaks reported to the North East Health Protection Team from 1 January 2012 to 31 December 2014 were included. Epidemiological (attack rate, symptom profile and positive associations with a suspected vehicle of infection), environmental (deficiencies in food preparation or hygiene practices and suspected vehicle of infection) and microbiological investigations are described. Forty-six outbreaks were included (83% reported from care homes). Enterotoxin (cpe) gene-bearer C. perfringens were detected by PCR in 20/46 (43%) and enterotoxin (by ELISA) and/or enterotoxigenic faecal/food isolates with indistinguishable molecular profiles in 12/46 (26%) outbreaks. Concerns about temperature control of foods were documented in 20/46 (43%) outbreaks. A suspected vehicle of infection was documented in 21/46 (46%) of outbreaks (meat-containing vehicle in 20/21). In 15/21 (71%) identification of the suspected vehicle was based on descriptive evidence alone, in 5/21 (24%) with supporting evidence from an epidemiological study and in 2/21 (10%) with supporting microbiological evidence.

C. perfringens-associated illness is preventable and although identification of foodborne outbreaks is challenging, a risk mitigation approach should be taken, particularly in vulnerable populations such as care homes for the elderly.

An epidemiological review of gastrointestinal outbreaks associated with Clostridium perfringens, North East of England, 2012–2014

Epidemiology and Infection / Volume 144 / Issue 07 / May 2016, pp 1386-1393


Temperature matters: 157kg of chicken and 61kg of meat to be disposed of in UAE

A total of 157kg of fresh chicken, that was being transported at an unsafe temperatures, will be disposed of immediately by order of the emirate of Abu Dhabi’s food sector regulator, the Abu Dhabi Food Control Authority (ADFCA).Chicken-Tikka_635549434140673686

An additional 61kg of mutton stored under unsafe conditions has also been confiscated and will be disposed of by the ADFCA, it announced in a statement sent on Monday.

The contaminated and spoilt food was found during random checks on fresh meat stores in the capital. Inspectors looked at the state of storage equipment, product quality, the condition of vehicles used for transportation and the adherence to food safety procedures during their visits.

Four vehicles used to transport the spoilt chicken were issued warnings for not maintaining the right temperature, and the two freezers that contained both fresh meat and spoilt samples were also isolated.

Ranking risk: E. coli O157:H7 and Salmonella growth on leafy greens

The objective of this work was to study the growth potential of E. coli O157:H7 and Salmonella spp. in leafy vegetable extracts at different temperature conditions.

lettuce.nov10Cocktails of five strains of E. coli O157: H7 and of S. enterica were used. Inoculated aqueous vegetable extracts were incubated at 8, 10, 16 and 20°C during 21 days. Microbial growth was monitored using Bioscreen C® . In spinach extract, results showed that for E. coli O157:H7 and Salmonella significant differences (p<0.05) for μabs (maximum absorbance rate) were obtained. For both pathogens, growth in chard was slightly lower. In contrast, iceberg lettuce and parsley showed the lowest values of μabs , below 0.008 h-1 . The coefficients of variance (CoV) calculated for the different replicates evidenced that at low temperature (8 °C) a more variable behaviour of both pathogens is expected (CoV > 180%).

This study provides evidence that aqueous extracts from vegetable tissues can result in distinct growth niche producing different response in various types of vegetables.

Finally, these results can be used as basis to establish risk rankings of pathogens and leafy vegetable matrices with relation to their potential growth.

Assessing the growth of Escherichia coli O157:H7 and Salmonella in spinach, lettuce, parsley and chard extracts at different storage temperatures.

J Appl Microbiol. [Epub ahead of print]

Posada-Izquierdo G, Del Rosal S, Valero A, Zurera G, Sant’ Ana A, Alvarenga VO, Pérez-Rodríguez F



Handwashing with Dr. Oz (‘never heard of him’)

I was talking to a medical doctor and a couple of his students, and a New York City trip is in the works, and I said I’d only been to NYC a couple of times, including when I was on Dr. Oz.

Dr. Oz“Who’s Dr. Oz?”

“A television celebrity medical doctor.”

“Why would he call himself Dr. Oz? Does he represent all of Australia?”

Communication breakdown.

One of the students explained who Dr. Mehmet Oz was and how he was spawned from Oprah.

“Never heard of him.”

Dr. Oz released a handwashing video and it’s not bad. They got the water temperature bit right (so please, everyone else stop saying it has to be warm water, that’s just a personal preference).

They also got the soap and friction bit right.

The 20-second bit? Not so right.

So I turned to handwasher-in-chief, Don Schaffner of Rutgers University, who offered the following comments:

“The U.S. Food and Drug Administration model food code says two things: In section 2-301.12 it says “warm” water must be used for handwashing.  It’s isn’t science based as far as I know.

“In section 5-202.12 it says the handwash sink must provide water at a temperature of at least 38 °C (100 °F).  Also not science based.

“The video mentions 20 seconds.  As far as I know, that’s not science based either, and while it’s a perfectly fine length of time, 30 seconds would be better, and 15 seconds would be almost as good.”