Sanitizers and produce: What works?

The aim of this study was to perform a meta-analysis of the effects of sanitizing treatments of fresh produce on Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes.

lettuce.skull.noroFrom 55 primary studies found to report on such effects, 40 were selected based on specific criteria, leading to more than 1,000 data on mean log reductions of these three bacterial pathogens impairing the safety of fresh produce. Data were partitioned to build three meta-analytical models that could allow the assessment of differences in mean log reductions among pathogens, fresh produce, and sanitizers. Moderating variables assessed in the meta-analytical models included type of fresh produce, type of sanitizer, concentration, and treatment time and temperature. Further, a proposal was done to classify the sanitizers according to bactericidal efficacy by means of a meta-analytical dendrogram.

The results indicated that both time and temperature significantly affected the mean log reductions of the sanitizing treatment (P < 0.0001). In general, sanitizer treatments led to lower mean log reductions when applied to leafy greens (for example, 0.68 log reductions [0.00 to 1.37] achieved in lettuce) compared to other, nonleafy vegetables (for example, 3.04 mean log reductions [2.32 to 3.76] obtained for carrots). Among the pathogens, E. coli O157:H7 was more resistant to ozone (1.6 mean log reductions), while L. monocytogenes and Salmonella presented high resistance to organic acids, such as citric acid, acetic acid, and lactic acid (∼3.0 mean log reductions). With regard to the sanitizers, it has been found that slightly acidic electrolyzed water, acidified sodium chlorite, and the gaseous chlorine dioxide clustered together, indicating that they possessed the strongest bactericidal effect.

The results reported seem to be an important achievement for advancing the global understanding of the effectiveness of sanitizers for microbial safety of fresh produce.

 Meta-analysis of the Effects of Sanitizing Treatments on Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes Inactivation in Fresh Produce

Applied and Environmental Microbiology, Volume 81, Number 23, December 2015

L Prado-Silva, V Cadavez, U Gonzales-Barron, A Rezende, A Sant’Ana


Cleaner cantaloupes: Sanitizers for rock melon

For health reasons, people are consuming fresh-cut fruits with or without minimal processing and, thereby, exposing themselves to the risk of foodborne illness if such fruits are contaminated with bacterial pathogens.

cantaloupe.salmonellaThis study investigated survival and growth parameters of Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and aerobic mesophilic bacteria transferred from cantaloupe rind surfaces to fresh-cut pieces during fresh-cut preparation. All human bacterial pathogens inoculated on cantaloupe rind surfaces averaged ∼4.8 log CFU/cm2, and the populations transferred to fresh-cut pieces before washing treatments ranged from 3 to 3.5 log CFU/g for all pathogens. A nisin-based sanitizer developed in our laboratory and chlorinated water at 1,000 mg/liter were evaluated for effectiveness in minimizing transfer of bacterial populations from cantaloupe rind surface to fresh-cut pieces. Inoculated and uninoculated cantaloupes were washed for 5 min before fresh-cut preparation and storage of fresh-cut pieces at 5 and 10°C for 15 days and at 22°C for 24 h. In fresh-cut pieces from cantaloupe washed with chlorinated water, only Salmonella was found (0.9 log CFU/g), whereas E. coli O157:H7 and L. monocytogenes were positive only by enrichment.

The nisin-based sanitizer prevented transfer of human bacteria from melon rind surfaces to fresh-cut pieces, and the populations in fresh-cut pieces were below detection even by enrichment. Storage temperature affected survival and the growth rate for each type of bacteria on fresh-cut cantaloupe. Specific growth rates of E. coli O157:H7, Salmonella, and L. monocytogenes in fresh-cut pieces were similar, whereas the aerobic mesophilic bacteria grew 60 to 80 % faster and had shorter lag phases.

 Efficacy of Sanitizer Treatments on Survival and Growth Parameters of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on Fresh-Cut Pieces of Cantaloupe during Storage

Journal of Food Protection®, Number 7, July 2015, pp. 1250-1419

Ukuku, Dike O., Huang, Lihan, Sommers, Andchristopher

NZ childcare centers warned on hand sanitizers

The Ministry of Education will warn all early childhood centers in New Zealand about the risks of alcohol-based hand sanitizer in the wake of an Invercargill 4-year-old girl becoming grossly intoxicated at her preschool.

dumbo-300x188The ministry has completed a two-week investigation into an incident at the Woodhouse Early Learning Centre that resulted in the girl being admitted to hospital with a blood alcohol level of 188mg, nearly four times the new legal driving limit.

The preschool owner, Jackie Woodward, believed the girl got intoxicated from drinking hand sanitizer at the premises without the knowledge of staff.

Her assertion has been backed up by the ministry, which has found it was “most likely” the child drank hand sanitiser.

“We’ve completed the investigation into the incident at Woodhouse Early Learning Centre, where a child was admitted to hospital due to a suspected alcohol intake,” ministry spokeswoman Katrina Casey said.

“Our investigation has shown that it was most likely the child ingested hand sanitizers at the center. We found no alcohol on the premises and the center manager has formally stated that there was no other form of alcohol on the premises.”

Good ole’ timey science-off: what’s the best way to wash hands, do sanitizers have a role?

Science is about a world–view of a topic and providing the data to back up that view.

Biology is especially messy.aust.handwashing.oct_.151

International handwashing day was October 15, but I was busy making a mess.

In Australia, the feds have a nice poster and how paper towel is to be used to dry hands, and I’ve never been in a Western country that has more hand driers than paper towel dispensaries.

Proper handwashing requires proper tools.

Ludwig writes in the current issue of Public Understanding of Science (November 2014 vol. 23 no. 8 982-995) to propose a methodological externalism that takes knowledge about science to be partly constituted by the environment. My starting point is the debate about extended cognition in contemporary philosophy and cognitive science. Externalists claim that human cognition extends beyond the brain and can be partly constituted by external devices. First, I show that most studies of public knowledge about science are based on an internalist framework that excludes the environment we usually utilize to make sense of science and does not allow the possibility of extended knowledge. In a second step, I argue that science communication studies should adopt a methodological externalism and accept that knowledge about science can be partly realized by external information resources such as Wikipedia.

Style is important, but content rules.

In this corner, Dr. Keith Warriner of the University of Guelph (that’s in Canada), who writes there are many old-wives tails, rumors and stories that are so ingrained that we don’t know if they are fact or fiction. The list is so long that a popular TV show called “The Myth Busters” is totally devoted to applying science to verify if myths are true or false. The show is for entertainment but it is when myths or non-substantiated knowledge, are actually applied in regulations and guidelines with the thought that someone must have done the science at some point in time.

As many new mothers in the latter part of the 19th century will verify, hand washing has been an essential intervention for minimizing the transfer of pathogens in clinical, food and other environments. The recommended method for washing hands was developed in 1980’s and has not changed significantly through the years. But is the method supported by science?

Myth 1: Antimicrobial soap provides superior hand washing results compared to normal soap

It has been widely accepted that antimicrobial soap is preferred over normal soap for increasing the efficacy of hand washing. Of all the aspects associated with hand washing the comparison of antimicrobial vs. normal soap has been studied to the greatest extent. The general conclusion is that antimicrobial soap supports a marginal increase in the number of bacteria removed from hands. If high inoculation levels are applied to hands then the removal with antimicrobial soap is statistically significantly compared to normal soap. However, with natural skin microflora there is no difference between the efficacy of normal and antimicrobial soap.  

There has been recent research that has suggested that antimicrobial soap can detrimental through disrupting the balance of the skin microflora and irritating the skin. On this basis all the evidence would suggest that antimicrobial soap has no advantages over normal soap.

Myth: Busted

Myth 2: Warm or hot water is better for hand washing than cool water

The FDA have reviewed the recommended water temperature used for hand washing no less than three times. The results of the deliberations was that 110F (43°C) should be set as the recommended temperature in the belief a greater proportion of microbes can be removed. However, all the scientific evidence available suggests that water temperature has no effect on the removal of microbes in the range of 4 -49°C. However, other research in this area has illustrated that water temperature does influence the duration of hand washing with cold or hot water leading to shorter rinse times due to user discomfort.  

Myth: Busted

Myth 3: Paper towels are perform better than air dryers

The method used for drying hands following washing is one of the most contentious issues in the hand hygiene arena. The general thought pattern when devising the hand washing guidelines was that hands needed to be dried to prevent acquisition of contamination from surfaces. This is true to a degree but it should also be noted that hand drying can contribute significantly in reducing microbial levels on hands following washing.

The majority of papers published to date have been pro-paper towels and even the “The Myth Busters” returned the same conclusion. However, it should be noted that many of the comparative studies performed the researchers used hot air hand driers that generated a gentle breeze making the user resort to completing the drying process using ones pants. More modern high speed (air blades) driers certainly can dry hands to the same extent as paper towels within 20 seconds. When a comparison is made between air blades and paper towels there is no difference in terms of microbial log reduction or degree of hand dryness. Given that high speed hand driers are not universally available, the evidence would support the view that paper towels are indeed better that hot air driers.

Myth: True

So does it matter if hand washing protocols are not science based?

It is apparent that many aspects of the hand washing protocol are not based on hard scientific evidence but this does not mean it is the wrong thing to do. Still, by reconsidering if anti-microbial soap is really necessary then skin health could be improved. The savings on energy and water usage by reducing the recommended wash time and temperature could also have a positive impact. Regardless of this, we always need to consider the science when devising guidelines.

In the other corner we have Don Schaffner of Rutgers University (that’s in Jersey). Don writes that an Internet troll is defined by Wikipedia as “a person who sows discord on the Internet by starting arguments or upsetting people… with the deliberate intent of provoking readers into an emotional response…”. Doug knows the way to troll me is to send a link and ask me to blog about it (he really just wants to call me a troll).

An article from features the headline “Simple Sickness Prevention: Hand-Washing vs. Hand-Sanitizer”, and asks: what is more effective, old fashioned soap and water, or the alcohol based hand sanitizer?

Not a bad start. The story goes on to feature Doctor Jaime Marks, Assistant Professor of Medicine at UW-Health, who offers a variety of opinions on hand washing and hand sanitizer use.

Dr. Marks says it’s okay to use either hand-washing or hand-sanitizer.

Hmm. the FDA CFSAN Food Code 2–301.16(A)(3) would disagree, but I think I’m starting to like Dr. Marks…

If you notice your hands are soiled, you’ll want to wash your hands. Hand washing is at least 45–60 seconds, like singing through “Happy Birthday” twice in your head. With hand sanitizer, you’d want to use it for 20–30 seconds.

Whoops. That went off the rails quickly. Dr. Marks is certainly entitled to his opinion, but I’d like to see the scientific peer-reviewed basis for those statements. I’d waged they don’t exist. At least I’ve never seen them.

Dr. Marks continues…

Both are about equal as far as getting your hands clean as long as your hands are not soiled.

Hmmm. Dr. Marks wins me back. Sort of. In fact sometimes hand sanitizers even work when your hands are soiled.

The story concludes with some muddled statements about good bacteria and bad bacteria, building an immune response and getting a flu shot that don’t really hang together, but I’ll give Dr. Marks partial credit for trying. More credit next time if you cite the literature.

Or, according to The Smashing Pumpkins, “Emptiness is loneliness and loneliness is cleanliness and cleanliness is godliness and god is empty, just like me.”

Schaffner on hand sanitizers: they’re a good thing

Friend of the blog Don Schaffner of Rutgers University writes in this guest post:

sanitizerI’m willing to go on record as saying that alcohol-based hand sanitizer is a good thing. In fact, we have published research which shows that it works to inactivate a gram-negative surrogate organism present on the hands even in the presence of visible food debris.

As Doug is sure to remind me, every time I mention the benefits of hand sanitizer, it’s not a magic bullet. For example, it doesn’t work very well against some viruses. That said I’m encouraged by research that shows that it is possible to tweak the formulation of such products to get better effectiveness against viruses. Hand sanitizer also doesn’t work very well against parasites like Cryptosporidium.

No matter what your opinion, I hope you would agree that more research is better. One example comes from a manuscript recently accepted for publication in the Journal Travel Medicine and Infectious Disease. I learned about the publication from a Reuters news story that Doug sent my way.  According to the abstract, the authors investigated the potential protective effect of hand sanitizer use on the occurrence of diarrhea and/or vomiting in 200 international travelers, who were returning home, at an international airport.

The authors report that travelers who used hand sanitizer reported diarrhea and vomiting significantly less frequently than those who did not (17% vs. 30%, OR = 0.47; 95% CI [0.21–0.97], p = 0.04). While the reported p value reaches the level necessary for publication, authors schaffner.facebook.apr.14should always beware of what we’ve come to call in my lab the green jellybean effect. There’s also a nice quote in the Reuters news story from Dr. Claire Panosian Dunavan, an infectious disease specialist at the David Geffen School of Medicine at UCLA in Los Angeles  who says “I suspect that the people who use hand sanitizer were more careful in ways that couldn’t be quantified.”

I was thinking the same thing. I was also thinking that someone ought to let those study authors know about Betteridge’s law of headlines.

Will I continue to use hand sanitizer? Of course. Do I think it will magically protect me from any illness?


Sanitizers or handwashing? Or both?

Installing alcohol-based hand sanitizer dispensers in classrooms may not mean fewer sick days for kids, a New Zealand study has suggested.

genitals.hand.sanitizerThe study, published today in the journal PLOS Medicine, found absence rates at schools that installed dispensers in classrooms as part of the survey were similar at those “control” schools which did not.

The research, led by Associate Professor Patricia Priest and University of Otago colleagues, involved 68 schools in Christchurch, Dunedin and Invercargill and nearly 2,500 pupils.

In schools randomly assigned to the “intervention” group, alcohol-based hand sanitizer dispensers were installed in the classrooms over two winter terms and the children were asked to use the dispensers after coughing or sneezing and on the way out of the classroom for breaks.

Dr Priest emphasizes that the study’s findings were not relevant to the importance of hand hygiene in general, nor did it change the message of cleaning hands before eating or after using the toilet, coughing or touching pets.

In a related story, the USA Today reports that alcohol-based hand sanitizers are better at killing germs and that soap and water is generally the best option but, hand sanitizers come in handy when you aren’t close to a sink.

80 crypto cases a year; handwashing is never enough: UK health chief warns over risk of infection from region’s petting farms

We have a paper coming out shortly about best practices at petting zoos and farm visits and state fairs and just hanging out with animals.

I’ll follow my own best practice and wait until it’s published to talk about it, but Dr Ken Lamden, the health chief of Cumbria and north Lancashire in handwashing.ekka.jpgthe UK is urging parents to be aware of potential infections that can be caught at farm attractions.

Over the past 20 years, an average of around 80 cases of cryptosporidium infection linked to visits to petting farms have been reported to Public Health England each year. This is out of a total of around two million visits to the 1,000 plus farm attractions in the UK, with peak visitor times during school and public holidays.

Dr Lamden, of PHE’s Cumbria and Lancashire Centre, said: “Visiting a farm is a very enjoyable experience for both children and adults alike but it’s important to remember that contact with farm animals carries a risk of infection because of the micro-organisms – or germs – they carry.

 “Anyone visiting a petting farm should be aware of the need to wash their hands thoroughly using soap and water after they have handled animals or been in their surroundings. Children are more at risk of serious illness and should be closely supervised to make sure that they wash their hands thoroughly.

“It is also very important not to rely on hand gels and wipes for protection because these are not suitable against the sort of germs found on farms.” 

Norovirus cruising woes

My friend and fellow NC State dude Chris Gunter (below, on the left, exactly as shown) texted me this morning while on his way to Houston. He’s about to embark on a cruise and his ship, The Caribbean Princess, was linked to 173 norovirus illnesses this week. According to Ben Souza of the appropriately named, Chris’ cruise is delayed while the good folks at the CDC Vessel Sanitation Program do an investigation.1014303_10102397059410553_886550941_n

There has been a confirmed norovirus outbreak on the Caribbean Princess.  Out of the 3102 passengers on board, 162 (5%) have reported ill in addition to 11 crew members.  The cruise ship will return to Houston one day early and arrive on January 31 due to a fog advisory.

When the ship returns to Houston, Texas, 2 CDC Vessel Sanitation Program environmental health officers will board the ship for a health assessment.  They will evaluate the outbreak and collect specimens for testing at the CDC lab.

One thing that popped up in the coverage of this week’s other cruise disaster, 600+ norovirus illnesses linked to the Explorer of the Sea, was the apparent focus on hand sanitizer as a control measure. According to passenger Claudia Cirisi, the stuff was everywhere.

“There were a lot of people in the bathroom getting sick and they had hand sanitizers all over, and you were constantly washing your hands. You couldn’t go into the dining rooms without having some Purell. They were washing down the railings; they were washing down the seats after you got out from the pool. They were washing anything that came in contact with the passengers”

While hand sanitizer that can be purchased at drugstores has its uses, reducing norovirus spread isn’t one of them. Pretty much all retail-available hand sanitizers suck when it comes to reducing norovirus viability. Same with the alcohol-containing wipes. Maybe what’s being used on board is a different formulation, but seeing some data would be nice.

Hand sanitizers didn’t protect Iowa kids against crypto after petting cows

This is why the UK says, handwashing with soap and water only at any petting farm or zoo.

A recent cluster of cryptosporidium cases cropped up after a Iowa preschool class visited a farm, Dr. Patricia Quinlisk, the Iowa Department of Public Health’s medical director, reported this morning. “While on the farm, the children petted cows and cow_hug_cumberlandate snacks,” Quinlisk wrote in a weekly email to public-health officials statewide. “The children did use hand sanitizer before eating; however, hand sanitizers are not particularly effective against crypto. Please continue to encourage handwashing with soap and water whenever possible.”

The Des Moines Register reports the parasite sickened hundreds of Iowans this summer, mainly via tainted swimming-pool water. Many of the patients suffered severe diarrhea. The outbreak has slowed now that most public pools have closed for the season. But infections also can happen in other ways, including contact with infected animals.

Quinlisk did not identify the preschool or say how many children became ill.

On Sept. 12, the state health department reported that there had been 861 confirmed or probable cases in Iowa so far in 2013. In all of 2012, there were 328 such cases.

’Sanitizer is a poor second to washing your hands’; norovirus outbreak at Yellowstone highlights camping health hazards

After 200 park employees and visitors reported bouts of gastrointestinal illness at Yellowstone National Park and nearby Grand Teton National Park this month, national park officials have warned visitors to be vigilant about hygiene.

The outbreak started on June 7, when a group touring the Mammoth Hot Springs complained of stomach flu and other gastrointestinal problems. norovirus-2After the tour group members reported their illnesses, about other 50 visitors and 150 park employees reported similar symptoms.

Preliminary reports found that they had norovirus, or “stomach flu,” which affects up to 21 million people, every year according to the Centers for Disease Control and Prevention.

Al Mash, spokesman for Yellowstone National Park, said campers who were worried about the outbreak should take care to properly store their food and wash their hands with soap and water before eating. “Don’t rely on hand sanitizer. It’s good for a while if you don’t have access to water,” said Mash. “But sanitizer is a poor second to washing your hands.”