Flesh-Eating Bacteria Washing Ashore in Florida — and Plastic Is to Blame

Flesh-eating bacteria is washing ashore in Florida — and more is headed its way — thanks to a massive cluster of plastic-polluted Sargassum that scientists believe is infested with the virulent Vibrio vulnificus strain of bacteria.

Sargassum, a brown microalgae that resembles seaweed and has been expanding in the Sargasso Sea and other parts of the ocean, is an ideal host for the Vibrio, which scientists have discovered cling to plastic intermingled in the seaweed, according to a new study published in Water Research.

There is currently a 5,000-mile wide clump of Sargassum, known as the “Great Atlantic Sargassum Belt,” that is floating towards Florida, according to Newsweek.

That Sargassum belt is almost twice the width of the continental United States.

“Our lab work showed that these Vibrio are extremely aggressive and can seek out and stick to plastic within minutes,” said Dr. Tracy Mincer, corresponding lead author and an assistant professor of biology at FAU’s Harbor Branch Oceanographic Institute and Harriet L. Wilkes Honors College. “We also found that there are attachment factors that microbes use to stick to plastics, and it is the same kind of mechanism that pathogens use.”

The unique relationship between the bacteria and plastic can create a vicious cycle that contributes to the growth of more Sargassum, thereby providing even more of an environment for the Vibrio. 

“Another interesting thing we discovered is a set of genes called ‘zot’ genes, which causes leaky gut syndrome,” said Mincer. “For instance, if a fish eats a piece of plastic and gets infected by this Vibrio, which then results in a leaky gut and diarrhea, it’s going to release waste nutrients such nitrogen and phosphate that could stimulate Sargassum growth and other surrounding organisms.”

Humans generally become infected with the Vibrio bacteria by eating raw or undercooked seafood; However, the CDC warns that an open wound that comes in contact with the bacteria could lead to necrotizing fasciitis — the flesh-eating bacteria infection, which can lead to amputations or death. 

The infected seaweed could hinder efforts to clean up Florida’s beaches as the Sargassum begins to wash ashore. According to the study, the beached Sargassum may carry high amounts of Vibrio bacteria.

Cases of Vibrio infections — and deaths — have been rising in Florida, according to the state’s health department. Cases more than doubled from 2021 to 2022, but that was largely attributed to Hurricane Ian’s impacts on the state.

A Vibrio infection is fatal for 1 in 5, according to the CDC, which cautions that some people die within a day or two of exhibiting symptoms.

“I don’t think at this point, anyone has really considered these microbes and their capability to cause infections,” said Mincer. “We really want to make the public aware of these associated risks. In particular, caution should be exercised regarding the harvest and processing of Sargassum biomass until the risks are explored more thoroughly.”

Although Sargassum has already started washing ashore in Florida, most experts expect the bulk of it to hit in June and July.