A bioterrorist attack has exposed a swath of Philadelphia to anthrax and thousands of residents need antibiotics to try to ward off the deadly bacterial infection.

That scenario was part of Saturday's training session for nearly 200 new volunteers with the Philadelphia Medical Reserve Corps.

"Imagine 20,000 Philadelphians coming through here, getting medications" for anthrax, said physician Steve Alles, standing in the gymnasium of the University of the Sciences in Philadelphia, where the training exercise was held.

The premise was a tad sensational. Credentialed volunteers are typically involved in medical care and first aid after major storms, or at city events such as the Philadelphia Marathon.

But the specter of anthrax was a reminder of why the national Medical Reserve Corps was created in the first place. The Sept. 11, 2001, terrorist attacks on the World Trade Center and, just a week later, the mailing of anthrax-tainted letters to news media and U.S. senators painfully illustrated the need for more organized use of medical volunteers.

In 2002, Congress allocated money to establish the Medical Reserve Corps program office in the U.S. Surgeon General's Office.

In 2005, the Philadelphia Department of Public Health launched the city's unit; it now has more than 1,800 volunteers who offer their medical, pharmaceutical, behavioral health, and other skills.

Three times a year, they are invited to training events like the one Saturday, which included a program overview, a talk on Ebola preparedness, and fun and games. (Fun fact: A survey of the Pennsylvania Medical Reserve Corps found most volunteers would step up for a terrorist or nuclear attack, but only 22 percent would help with mud or snow removal.)

"Years ago, we started [training] with 20 volunteers," said Neale Batra, coordinator of the city's reserve corps. "This year, I had to cut off registration at 200."

The university gymnasium had been set up for the "point-of-dispensing" practice - POD for short - with caution tape and four long rows of cafeteria tables. After watching a video of an actual POD, the volunteers took turns playing the roles of medical screeners, medication dispensers, and patients getting pills for their families.

The screeners, equipped with various cheat sheets, had the hardest job: Review the patients' intake forms and then check off the antibiotics they should be given. Doxycycline is the standard anthrax-prevention drug, but some children and people with allergies get ciprofloxin or amoxicillin.

"It's a little rough going at first!" Alles, who manages the city Health Department's emergency preparedness program, yelled over the hubbub. "There's definitely a learning curve. So call me over if you have questions."

Within 15 minutes, 40 pretend patients had moved through the POD, picking up, and immediately returning, their empty plastic bottles of drugs.

At the dispensing table, Sylvie Mulvaney, 48, of Abington, a nurse at Einstein Medical Center, said she volunteered for the medical corps as a way to give back to the community.

Ditto, said volunteer Alex Fevry, 21, a pharmacy student at the University of the Sciences.

"Pharmacy school is ridiculously hard and I have an exam on Tuesday," he said. "But I really wanted to do this."

Thankfully, the corps has never been called up for a bioterror attack, but POD opportunities are fairly routine, Alles said. This fall, for example, volunteers helped give flu shots to about 1,700 police, emergency responders, and their families.

Not that the corps' role is well-known.

Diane Murphy, 49, a nurse at the Hospital of the University of Pennsylvania who joined the corps two years ago, said most of her friends had never heard of it.

But being unsung does not mean being unimportant. At last year's Philadelphia Marathon, a runner went to the first-aid tent with chest pains.

"It was before the race," Murphy recalled. "We sent him to the hospital. We may have saved his life before the race even started."

mmccullough@phillynews.com

215-854-2720 @repopter