Medical experts and scientists said Friday it's unlikely that a German sailor with a bacterial skin infection that's resistant to antibiotics contracted the illness in polluted Olympic waters.

Sailor Erik Heil fell ill after competing in a pre-Olympic test event held Aug. 15-22 in Rio's Guanabara Bay, into which dozens of rivers dump raw sewage.

Heil needed daily hospital treatment for multiple infections on his legs and hip. The Berlin hospital where he was treated said he contracted MRSA, a type of bacteria resistant to many antibiotics.

The athlete, who told The Associated Press Thursday that he's now largely recovered, said he had never before had any such infections and felt that he got sick because of the water in Rio.

However, some top global experts on superbacterias told the AP that it's unlikely, though not impossible, that Heil got the infection from the water.

"You wouldn't expect to see somebody get MRSA from contact with water," said Dr. Pritish Tosh, an infectious disease physician and researcher at the Mayo Clinic in the U.S. "It's usually spread by skin contact."

In the past decade, MRSA and other so-called "superbacterias" have made the leap from being mostly contained in hospitals to infecting people who have not been in a hospital, a worrying trend.

Last December, Brazilian researchers from the Health Ministry's Oswaldo Cruz Foundation research lab, published results of a study showing they found bacteria containing the KPC enzyme that make them resistant to antibiotics in the Carioca River.

That river dumps its fetid contents into the waters off Flamengo Beach — where Olympic sailing events take place. The report underscored that there were no known cases of people falling ill from the bacteria and no sailors from last month's event are known to have contracted KPC.

Valeria Harwood, chairwoman of the Integrative Biology department at the University of South Florida and an expert in recreational water contamination and antibiotic-resistant bacteria, said that KPC is known to be present in waters contaminated by human sewage, like Rio's. She said it posed a greater danger to those in contact with the water than the infection Heil got.

However, Harwood said MRSA is "certainly found in sewage" — some recent studies in the U.S. have found its presence in wastewater treatment plants. But because it's a bacteria mostly found in the oral cavity and not in the gastrointestinal tract, it's less prevalent in sewage than KPC.

She said that it's "within the realm of possibilities" that the German sailor got the MRSA infection in Rio's waters, but agreed with Tosh that it seemed unlikely because it's a bacteria that hasn't been shown to spread much via water.

Additionally, it's nearly impossible to say with certainty where Heil got his infection. MRSA can "colonize" a person and not show physical symptoms for months or years, both specialists said.

"You would have to get the DNA 'fingerprints' of the bacterial infection of the patient, then match it to the DNA 'fingerprints' of bacteria found in the water," Harwood said. "But the water that's there when you go back to take a sample wouldn't be the same water the patient was exposed to weeks ago."

Dr. Alberto Chebabo, head of Rio's Infectious Diseases Society, concurred that figuring out where Heil was infected was a nearly impossible feat.

"He could have contracted it here in Brazil, in another place where he may have been before including in Germany itself," he said. "We know that MRSA is present here in Brazil, but we don't have any evidence of any infection resulting from contaminated water."

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Associated Press writers Jenny Barchfield in Rio and Ciaran Fahey in Berlin contributed to this report.

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