Cherney Blog: Inside The Petridish

Your blog resource for education, experience, and a good read!

Cherney Blog: Inside The Petridish

Your blog resource for education, experience, and a good read!

Let's Talk About It: E.coli & Staph

Posted by Lauren Ellie on Feb 23, 2021 10:12:10 AM
Lauren Ellie
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It's time for our final subject in our series "Let's Talk About It"

I know, I know...

It’s sad to reach the end of the series, but don’t worry... there are more informative and educational blogs on the way! Today’s topics are bacterial organisms that you are probably fairly familiar with but before we get into the specific organisms, let’s talk a little bit about toxins.

 Tummy painBacterial toxins are toxic substances that are produced and released by bacteria to target other bacterial or host cells. These bacterial toxins cause food poisoning when ingested by the host. The two bacteria we talk about today (E.coli and Staph) are both capable of producing toxins that can make consumers ill.
There are two types of toxins: Endotoxins and Exotoxins.
An endotoxin is a toxin that is present inside a bacterial cell and is released when the cell disintegrates.
For example: Staphylococcus aureus can release an endotoxin that causes illness.
An exotoxin is a toxin released by a living bacterial cell into its surroundings.
For example: Some E coli bacteria are capable of producing exotoxins that can cause illness.

Let’s dig in a little deeper to better understand each of these organisms and their growth conditions.



Escherichia coli

There are two reasons not to drink toilet water. Number one and number two 💩

E-coli dishSome E coli are capable of producing toxins, known as shiga toxins, this group of bacteria is referred to as STEC (Shiga-Toxin producing E Coli). These toxins are usually ingested through contaminated food or water supply. E. coli O157:H7 is the most well-known member of this group, however there are others that are cause for concern. The non-O157 serogroups are less likely to cause severe illness but should not be ruled out because sometimes they can be serious. The non-O157 STEC that have caused illness in people in the United States include O26, O111, and O103. Here at Cherney we can test for all of them, whether you’re specifically testing for O157 and or the other members of the STEC group!

Growth Conditions: E.coli grow at temperatures from 28°F to 122°F. In foods, growth is poor or very slow at 41°F or lower. They grow in a pH range of 4.4-9.0.


E coli in food products: Primary sources of E coli outbreaks are raw or undercooked ground meat products, raw milk, unpasteurized juices, and fruits or vegetables. E coli bacteria can be introduced into meat products during processing, can spread from cow’s udders to its milk, or can contaminate raw fruits and vegetables that have come into contact infected animal feces.

E coli in your environment: Keeping in mind that this group of organisms is present in feces, it’s no wonder why all food production environments stress the importance of washing your hands after using the restroom! E coli bacteria can be spread from one place to another simply by an employee who did not effectively wash their hands after using the restroom before returning to work. Because E coli can be present in infected animal feces, it’s easily spread from place to place on the bottoms of shoes, equipment, carts, etc. It’s important to consider sanitary design and control traffic flow throughout your facility. Keep in mind that it’s not only spread directly through feces, E coli can also be present in a contaminated water or irrigation system so it’s important to monitor your water supply as well.




How about one last joke!
So a bacteria walks into a bar and goes back into the kitchen. The bartender stops him and says, "Hey, you're not allowed in there!"
The bacteria replies, "It's ok, I'm staph (staff)."

StaphThe Staphylococcus genus includes at least forty species and numerous subspecies. At its most basic, the genus is divided into two groups based on their ability to clot plasma, Coagulase Positive or Coagulase Negative. A coagulase test is testing for an extracellular protein on the cell surface that is able to form a clot in the presence of the plasma reagent.

Most customers are mainly concerned with coagulase-positive staphylococci since the most pathogenic species, S aureus, is coagulase positive. Staphylococcus aureus is capable of causing food poisoning via toxin production. This specific toxin is referred to as staphylococcal enterotoxin. If customers have product with coagulase positive staph present, they are able to choose to have the test completed for staph enterotoxins as well.

 Growth Conditions: The temperature range for growth of Staph is 39–118°F, with an optimum of 98.6°F. Growth of Staph occurs over the pH range of 4.0–8.0, with an optimum range of 6–7. Staph is uniquely resistant to adverse conditions such as low water activity and high salt content.

Staph in food products: Staph is capable of thriving in a wide variety of foods: dairy products, vegetables, meat products, including cured meats that do not typically support the growth of other foodborne pathogens. Staphylococcus can be resistant to freezing and survives well in food stored below -20°C. However, Staph is readily killed during pasteurization or cooking, but if toxin is produced, the toxin is not killed by heat and can persist in food products. When in food, very small doses of toxin can cause staphylococcal food-borne illness.

Human GlovesStaph in your environment: Humans are common asymptomatic carriers of S. aureus in their nose, throat, and on their skin. Thus, food handlers and line production workers can be an important source of contamination. Staph frequently contaminates food products post pasteurization due to prolonged inadequate handling of the product, or insufficient storage practices.

Also the ability to form biofilms allows S. aureus to survive in hostile environments and the presence of biofilms can enhance the recurrence of food contamination within food production areas.

Hopefully over the course of the “let’s talk about it” blog series, you’ve gained some insight and knowledge about these types of bacteria that are most frequently requested here at Cherney. However there are additional tests of importance as well. When addressing the issue of food safety, there are many other bacteria of concern that can also cause foodborne illnesses. So if you’re ever in need of additional information about any of our wide range of tests or suggestions regarding your testing options, just reach out to us at Cherney and we would be glad to help you with any of your testing needs and/or questions.

Check out our other Blogs, or check out our Webinars! They are loaded with interesting information. 

Topics: Continuing Education, Cherney Micro, Food Safety, Environmental Monitoring, Microbiology, Food Safety Modernization Act (FSMA), Service to the Customer, Technical Services, E.coli, Staphylococcus, Toxins