By: Alice Vo Edwards

Amongst concerns about genetically engineered foods and their effect on human physiology, scientists are making headlines with a new type of genetic modification – genetically modified bacteria. Researchers at Duke University have found a way to use a genetically modified version of Salmonella to treat Glioblastoma. Glioblastoma is a particularly malignant type of brain tumor. According to the American Brain Tumor Association (ABTA), brain cancer patients with the glioblastoma form of brain tumor typically have such poor survival rates that patients are usually given ranges for how many years they might expect to live, not whether or not they will die. This type of brain cancer makes up more than 15% of all brain cancers and is one of the hardest to treat due to the type of brain cells generally affected, multiple simultaneous cancer cells and/or tumors replicating simultaneously, and the dangers of surgery on potentially inflicting damage on the brain.

What is Salmonella?

Salmonella is a bacterium that the Centers for Disease Control and Prevention (CDC) classifies as being part of the Enterobacteriaceae family. Salmonella can also be divided into multiple subtypes based on slight differences in variants in the bacteria’s structure. The two broadest definitions are typhoidal and non-typoindal, based on whether or not causes typhoid fever. When discussing Salmonella, usually the non-typhoidal serotype (think of these as variants) are what they are reporting on. The most common of these are Enteritidis, Typhimurium, Newport, and Javiana.

Who does Salmonella affect?

The CDC estimates that 1.2 million Americans become ill each year from non-typhoidal Salmonella. Of these, 450 will die from a severe Salmonella infection. Salmonella is dangerous. According to the CDC, while less than one eighth of all foodborne illness outbreaks are caused by Salmonella, Salmonella is responsible for the most hospitalizations – 64 percent. The CDC states that there are 30 times more infections than those that are actually confirmed with laboratory tests, as many people have mild enough symptoms they do not go to the doctor or a hospital. These individuals can be accidental carriers or cross contamination.

How has Salmonella been changed to be life-saving?

The researchers, Nalini Mehta, Johnathan G. Lyon, Ketki Patil, Nassir Mokarram, Christine Kim, and Ravi V. Bellamkonda, genetically modified strain of Typhimurium, one of the common forms of Salmonella. In their report, “Bacterial Carriers for Glioblastoma Therapy” they stated that when they did so, it was able to destroy the cancer cells and keep rats alive over 100 days, compared to the rats who did not receive the genetically modified bacteria. Those rats who did not receive the modified Salmonella strain lived, on average, only 26 days. Ken Kingery of Duke University suggests that, in humans, this might relate to giving people an additional 10 years to live.

Will this research stop Salmonella food poisoning? 

While this research may seem promising to scientists and those who develop brain cancer, this research does NOT affect individuals who contract Salmonella from any of the current bacterial strains. The scientists have designed their genetically modified version of Salmonella to self-destruct when it runs out of “food” (i.e., brain tumor tissue).

What are the side effects to injecting genetically modified Salmonella bacteria in people’s brains?

At this time, only a short-term study was performed on the rats so there is no data on what could happen to people. Movies and television shows suggest horrific outcomes, such as brain mutations and zombification, but there is no data to support this contention. On the other hand, with only one study performed at this time, it is far too early to say that this type of treatment would be genetically safe for humans or to even hypothesis about the potential outcomes. Just as with Salmonella, there are already multiple known strains. Similarly, once a genetically modified strain is created, it also has the potential for mutation and adaptation in unknown ways. The very aspects of this bacteria that make it so attractive for this brain tumor therapy could make it dangerous in its possible future mutations. Do these risks outweigh the benefits to potential brain cancer survivors? Time and future research, will tell.

What should I do to avoid Salmonella food poisoning?

For now, continue to follow general safety precautions to avoid the common types of Salmonella poisoning.

The and the CDC recommend the following food safety tips:

  • Avoid eating high-risk foods such as raw eggs or poultry;
  • Refrigerate food before cooking;
  • Make sure your refrigerator is 40 degrees Fahrenheit or colder to minimize bacterial growth;
  • Wash hands, cutting boards, and countertops thoroughly before cooking and eating;
  • Separate meat, poultry, and seafood that are normally washed and cooked prior to eating from any ready-to-eat foods to avoid cross-contamination; and
  • Do not prepare food for others if you have any of the symptoms of Salmonella (diarrhea, vomiting, etc.) as this can increase the likelihood of cross contamination.

Did you know?

  • Clean eggs can still be infected.

People in the past contracted Salmonella from eggs that had not yet been washed and cleaned. Now that eggs come from the store in clean cartons, pre-sanitized, many people assume they are safe. Unfortunately, there are new strains of Salmonella that are carried inside the egg.

  • You’re more at risk during hot months.
    More cases of Salmonella poisoning occur in hot months because the bacteria multiplies faster. It is important and a good practice to follow the manufacturer’s label instructions of food items and keep food that is recommended to be refrigerated cold until you are able to eat it.
  • Re-refrigerating cold food that has been left out is a bad idea
    Do not eat refrigerated foods after they have been unrefrigerated (for example, it is not a good idea to leave a yogurt in your car for a day where it can get warm, re-refrigerate it, and eat it the following day. A low-amount of bacteria can quickly become a high-amount that can be harmful and cause symptoms.
  • Sunny side up is not hot enough
    The CDC reports Salmonella occurring even with people who eat eggs with runny yolks. The risk is not worth the danger.