Double Dip Yuck

08/10/2017 08:36 am ET

You know it’s wrong, yet you nearly always see it at get-togethers – double dipping. As microbiologists, we vividly imagine the exchange of microbes via the chip and dip bowl, but it is gross no matter what your job is.

Let’s start with a cracker. Scientists discovered that once a cracker has been bitten, it carries about 1,000 more bacteria than an unbitten one. They tested chunky hot salsa, chocolate syrup and cheddar cheese dip produced by well-known companies. Before dipping, none of the dips contained detectable bacteria. After double dipping, the chocolate and cheese dips contained 750 to 1,000 bacteria per teaspoon. The salsa was found to contain about 5,000 bacteria per teaspoon after double dipping, probably because of the way it drips back into the bowl after each scoop. Because salsa is acidic, the number of bacteria declined over time, and after two hours it was at the same level as in the chocolate or cheese dips. The situation gets worse if multiple people engage in double dipping, increasing the number and adding different types of bacteria to the dips.

The oral microbiome is a complex mixture of about 700 different types of bacteria, of which only about half are named and one third have never been grown in a lab. In a study of 120 people from 12 locations around the world, there were no significant differences in their oral microbiomes despite the obvious differences in environments and diets.

Oral bacteria include those that cause two of the most common diseases, dental cavities and gum disease. The oral cavity can also include bacteria that can cause a heart infection called endocarditis, bacteria that can cause brain and liver abscesses, and bacteria that cause a variety of intestinal disorders.

The oral microbiome also includes viruses, some of which make people sick. Viruses that can be found in the mouth can cause common illnesses like colds and the flu, as well as more serious illnesses like mumps and rabies. Other dangerous viruses found in the mouth can include HIV and hepatitis during certain phases of infection, the herpes virus that causes cold sores and the human papilloma virus that is responsible for warts and cancer.

Other microbes in the mouth include protozoa, fungi and archaea. Protozoa in the mouth include an amoeba and an oral trichomonas. They are harmless, but they are more abundant in the mouths of those with poor oral hygiene. Oral fungi include Candida species, which are yeasts that cause problems for people with compromised immune systems. Archaea are a group of single-celled organisms that are similar to bacteria, and the ones in the mouth do not appear to cause disease.

It has been estimated that the mouth contains 20 billion bacteria. When you add an unknown number of viruses, fungi, protozoa and archaea, you have a zoo of microbes to share via double dipping. Share your latest good news, a favorite recipe or valuable advice, but don’t share your microbiome with others at a party.

Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at www.medicaldiscoverynews.com.

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