2 Investigates: Unusual bacteria found on San Francisco public transit

Bay Area commuters may be carrying home more than they bargained for if they ride public transit. Researchers at San Francisco State University discovered a rare bacteria usually only found in Asia on MUNI, according to the results of a recent swab tests on two public transit systems.

SFSU biology researcher Darleen Franklin collected samples from random BART trains and MUNI buses in April, to examine what’s on the seats, handles, railings, and other commonly touched surfaces.

“We don’t want to see things like Methicillin-Resistant Staph Aureus or Vancomycin-resistant Staph Aureus,” said Franklin, referring to two types of bacterium that can cause dangerous skin and blood infections and are resistant to many types of antibiotics.

“I think it’s really important when it comes to public health,” she said. “We need to know what microbes are out there that could potentially make people sick.”

The analysis of Franklin’s swab tests on MUNI revealed some surprising results.

“We found this one strain that was difficult to identify at first,” she said.

Franklin says her lab sequenced the DNA of the mysterious bacteria found on MUNI bus line 28, and identified it as Pigmentiphaga. Franklin says the bacterium has only been found in the South China Sea and in waste water from South Korea. There’s also been one case of the bacteria found in a patient in Canada.

READ: SFSU swab test results on BART and MUNI

SEE: Test results pictures and presentation

Franklin says researchers don’t know enough about it to tell whether it’s dangerous to public health or not.

“Anything like that is, of course, a concern,” said MUNI representative John Haley. MUNI lightly cleans its 800 buses every night and deep cleans them every 30 days.  Haley insists that despite Franklin’s results, he believes MUNI buses are “definitely safe” for the public.

“I think we can always do more,” said Haley. “We’re running more service, carrying more riders, probably could do more cleaning.”

In the meantime, Franklin says more research needs to be done into Pigmentiphaga to understand it and how it may impact public health.

SFMTA spokesman Paul Rose said Thursday that experts with the city's Department of Health looked into the bacteria and found that it is "non-pathological" based on their information, they believed, "nothing to worry about."

In 2011, Franklin conducted similar swab tests on BART back when the transit system had cloth seats. Her results showed nine different strains of bacteria on seats, including fecal bacteria antibiotic-resistant bacteria. Results also revealed several types of mold.

But since switching to vinyl seats, the results from Franklin’s recent BART swab tests only showed Staph aureus, a common bacterium that is found on the skin and generally considered harmless. Franklin calls the move away from cloth seats on BART a “great move” to improve public health, but also stresses that not all types of germs or bacteria are bad.

BART workers clean all 669 cars in the transit system every night. Every four months, at least seven cars undergo a complete sanitization.

According to similar swab tests performed by a team with the website Travel Math, the Bay Area ranks as the number two dirtiest public transit system in the country. New York City topped the list. See their results here.