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Bacteria Form Gangs to Evade Sanitizers

Posted in Our Blog on February 8, 2024

They say there is strength in numbers. As it turns out, this also applies to bacteria as well. A recent Penn State study published in the journal, Biofilm, demonstrated that common sanitizers often used in foods are far less effective when Listeria has a posse on hand. This conclusion was made based on experiments performed on samples from tree fruit processing facilities.

What does this mean for the consumer?

Let’s find out!

How the Gang Operates

Listeria monocytogenes, a bacterial pathogen that is responsible for the illness listeriosis, is a seriously bad bug in that it is responsible for around 1,600 illnesses in the United States each year and results in about 260 deaths. While Listeria is commonly associated with dairy and other foods, about the time of the study’s inception, fruit tree produce linked to Listeria outbreaks were on the rise.

And so, fruit tree processing facilities became the focus of the study.

Penn State food scientists discovered that other bacterial families “co-occur” with Listeria monocytogenes in these tree fruit packing facilities. Non-harmful bacteria such as Pseudomonadacea, Xanthomonadaceae, Microbacteriaceae, and Flavobacteriaceae are often seen in the same hoods – food processing facilities.

It turns out, when these baddies hang out together, they form what is called a biofilm. This biofilm provides an almost physical barrier between sanitizers and Listeria monocytogenes, making it take significantly longer for the sanitizer to reach and kill the harmful bacteria.

It’s almost as though the bacteria making up the biofilm are defending the Listeria bacteria, saying, “you have to get through us first!”

By itself, the Listeria bacteria are more vulnerable to the sanitizer.

These bacteria and biofilm can persist in food processing environments for quite some time. Years even! This phenomenon is often responsible for recurrent contamination. Just when the facility thinks they have it under control, a small amount of the bad bugs peek from around the corner it was hiding in and it starts all over again with cross contamination.

Just How Bad Is It?

The Penn State study considered a common antimicrobial sanitizer often found in hand soaps, hand sanitizers, and household sanitizers – Benzalkonium chloride (BAC). Concentrations of BAC ranging from 150 to 1000 parts per million (ppm) were used to assault different combinations of bacteria. These broad-spectrum quaternary ammonium compounds are commonly used for this purpose.

Just how resilient is Listeria bacteria to the sanitizer?

When a biofilm is present, it takes 2-hours of exposure time (or more in some cases) to significantly reduce the amount of Listeria monocytogenes bacteria on a surface. This is largely due to the biofilm acting as a bulletproof vest.

When alone, however, it is a different story altogether. In the absence of defending bacterial biofilm Kevlar, the lone Listeria colony can be decimated in as little as 30 minutes.

What Happens if Listeria Isn’t Killed?

If Listeria bacteria aren’t killed or removed from food before you eat it, or surfaces you touch and put your hands in or near your mouth aren’t properly sanitized, you can become sick. Certain groups of people are categorized as “higher risk” or easy marks, meaning they are more susceptible to infection when exposed and may experience more severe symptoms.

Who is included in this “high risk” group?

  • People who are pregnant and their newborns
  • Adults aged 65 or older
  • Those with a weakened immune system

Other normally healthy individuals can still become sick from Listeria infection, though they rarely become seriously ill.

Listeriosis Symptoms

If you are exposed to Listeria bacteria and become sick, your illness may fall into two categories. Intestinal illness and invasive illness.

Intestinal Illness

Intestinal illness is pretty much what it sounds like. Your symptoms are fairly straightforward intestinal symptoms. People who are pregnant often experience milder symptoms, but it usually includes diarrhea and vomiting that starts within 24 hours of consuming the contaminated food and lasts between 1 and 3 days.

Listeriosis intestinal illness is usually underdiagnosed because most people ride out the symptoms since the illness is usually not serious enough to seek medical attention. Those who do get medical help for dehydration or other symptoms may not even be diagnosed. The healthcare provider would need to order a specific test for Listeria monocytogenes to properly diagnose the infection. Unless serious or invasive, antibiotics are not administered, so knowing the specific bug is usually not all that important to your doctor.

Invasive Illness

Invasive illness on the other hand, occurs when the bacteria spreads beyond the digestive system and enters other parts of the body. Symptoms are broken up into two categories because people who are pregnant experience different types of symptoms.

Invasive illness in pregnant people often presents as flu-like symptoms. All the usual fever, muscle aches, and fatigue you would expect with the flu. It is not uncommon, however, for pregnant people to show no signs of illness at all. The bigger risk comes in the form of increased chances of miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.

Invasive illness in non-pregnant people also presents flu-like symptoms, but often includes headache, stiff neck, confusion, loss of balance, and/or seizures. The mortality rate is also high. Nearly 1 in 20 non-pregnant people with invasive listeriosis will die from the infection.

Long Incubation Period

An incubation period is the time between exposure to a pathogen (e.g. eating contaminated food) and when you begin to feel symptoms.

With Listeria, unfortunately you could be infected with the harmful bacteria for quite some time before you begin to show symptoms. While sometimes people can show symptoms at 24 hours to 2 weeks after exposure, it can be up to 70 days before some start to feel sick.

What Should You Do If You Have Been Attacked by Listeria

If you have fallen sick with listeriosis, there are a few things you can do to help yourself through the process.

Stay Hydrated

A crucial aspect of recovering from diarrheal illness is staying hydrated. Vomiting and diarrhea remove important water from your body. Replenishing it will help your cells stay healthy as you recover.

Make a List

As soon as possible, make a list of the foods you have eaten and where you got them. Also retain packaging if you are able to. This will help investigators with traceback activities to determine the root cause if your illness is part of a larger outbreak.

Get Advice

Get your own strength in numbers. If you have become sick at the negligence of others, you may have a legal case. The Lange Law Firm, PLLC is experienced at helping people through Listeria outbreaks to hold accountable those responsible for preventable illnesses. Call (833) 330-3663 or click here to fill out the online form for a free consultation.

By: Heather Van Tassell