SAN DIEGO -- About 17 million pairs of feet move through Lindbergh Field Airport in San Diego every year. Each passenger is asked to take off their shoes at security. Some are clean, some are dirty, and some carry diseases, 10News reported.

"If there are individuals walking barefoot or with socks, they will transmit to another person walking over the same spot," lower leg desease expert Dr. Daniel Lee said.

What do socked or barefooted passengers leave behind? 10News used petri dishes to gather samples where passengers picked up their carry-ons off the conveyer belt at the security checkpoint.

After sampling in San Diego, a 10News employee headed to Las Vegas and Phoenix -- two popular destinations for San Diegans.

Investigative reporter Marti Emerald gave the samples to Quadrants Scientific in Rancho Bernardo.

The lab identified a mold from McCarron Airport in Las Vegas as trichophyston, which causes ringworm and favus, a nasty disease of the scalp.

The next test was from Sky Harbor Airport in Phoenix, where samples were lifted to test for bacteria.

Scientists found bacteria and fungus unique to the areas where passengers removed their shoes.

"I do have concerns over the organisms you found," Lee said. "Staphylococcus causes skin infections that goes deep through the layers and people who are sensitive can pick it up."

Lee said this particular organism is resistant to many of the antibotics used these days.

"The other organism I saw was Neisseria. It is of the species and genus that can lead to gonorrhea," Lee said.

Lee suggests wearing medical booties through security. Airports in Phoenix and Dallas offer free booties for flyers. Lindbergh Field does not, but could that may be changing.

It is illegal to force anyone to take off their shoes, but passengers who don't comply may be sent to a secondary security checkpoint.

"We looked at that before more as a customer convenience. We were told the floors were perhaps too cold," said Diana Lucero of the Airport Authority.

The San Diego Airport Authority intends to revisit the idea of handing out booties as part of its response to the 10News findings.

"We are very concerned about the health of the traveling public. Any remedies that have to implemented as a result of this, we will certainly move quickly in conjunction with the Transportation Security Administration to implement them," added Lucero.

The Airport Authority will test carpets themselves, and will clean and sanitize floors in the security areas more often.

They are also discussing the possibility of offering booties similar to the ones given away in Dallas and Phoenix airports.