(Cahuita) A researcher thinks he can discover new antibiotics in Costa Rica by studying the bacteria present in the coat of sloths, after noticing that these tropical animals never get sick.

According to Max Chavarria of the University of Costa Rica, sloths have a unique biotope of insects, algae and bacteria in their coats that seem to protect them.

“If someone studies the fur of a sloth, they will see movement: moths, different species of insects […] a very large habitat and, obviously, when there are many kinds of organisms, there must be a system that controls them,” he told AFP.

During his research, since 2020, the scientist has proven that “these are microorganisms (which) are able to produce antibiotics that help regulate the presence of pathogens in the coat of sloths”.

“These are bacteria that belong to the genera Rothia and Brevibacterium,” says the researcher who published the results of his studies in the scientific journal Environmental Microbiology.

The whole question is whether these antibiotics have a future in the pharmacopoeia for humans.

Sloths, two species of which coexist in Costa Rica – the Bradypus variegatus or three-toed sloth, and the Choloepus hoffmanni or two-toed sloth – live in the trees of the tropical forests of Central America, especially on the Caribbean coast of Costa Rica. , in a humid climate with temperatures ranging from 22 to 30 °C.

The population of these placid mammals – also present in Bolivia, Brazil, Colombia, Ecuador, Honduras, Nicaragua, Panama, Peru and Venezuela – is considered to be in “decline” by the International Union for Conservation of Nature (IUCN).

In Costa Rica, American Judy Avey administers the Cahuita Sloth Sanctuary, which she founded with her late Costa Rican husband Luis Arroyo. There are collected injured animals, to be cared for.

Judy Avey used to live in Alaska, and when she arrived in Costa Rica, she didn’t even know these animals existed.

In 1992, the couple rescued and cared for their first sloth, named “Buttercup”, and around 1,000 have since passed through the sanctuary on the Caribbean coast some 200 km from San José.

It was only natural that Max Chavarria contacted Judy Avey to study the sloths, cared for after being electrocuted on high voltage cables, or knocked down by cars, injured by dogs or separated from their mothers as children.

“We have never taken in a sick sloth […] some are burned by high voltage cables and have their arms injured […] but they have no infection,” notes Judy Avey.

Max Chavarria cut hairs from 15 individuals of each of the two species and made cultures in the laboratory to study them.

After three years of research, the scientist has counted around twenty “candidates” producing antibiotics, but everything remains to be done to consider an application on humans.

“You have to first understand the system (which produces immunity in sloths) and what molecules are involved,” explains the researcher.

Nature is the first of the laboratories, according to him, which cites the example of penicillin, discovered in 1928 by the Briton Alexander Fleming, Nobel Prize in medicine in 1945, from fungi which naturally synthesize this antibiotic.

The discovery of new antibiotics is a key issue since the World Health Organization (WHO) warns that resistance to current antibiotics could cause 10 million deaths each year by the middle of the century.

“That’s why projects like ours can help discover new molecules that can be used, in the medium or long term, in this battle against antibiotic resistance,” says Max Chavarria.