Bob Murken's 25-minute bike ride down Kelly Drive and on to City Hall each morning is a time for contemplation.

"You are zooming down a hill, wind in your face, it's sunny. It feels good," Murken, the city's director of legislative affairs, said of his daily rides to work. "That's why I've always loved it."

These days, that time is all the more precious.

Just months ago, Murken was hours away from perhaps never riding a bike again, or worse.

The thinly built 41-year-old father of two was attacked in March by flesh-eating bacteria, known as necrotizing fasciitis. It is a rare disease that kills about 25 percent of its victims, according to Murken's surgeon, Mark Kaplan.

By the time Murken's doctors figured out what was wrong with him, his kidneys were starting to fail. Had doctors at Einstein Medical Center not taken him into surgery immediately on March 31, Murken could have died. After five surgeries and three weeks in critical care, Murken was able to return to his home in Roxborough.

It wasn't until mid-August that he was riding his bike to work again.

"It was like this should be this momentous moment and like all this stuff is going through my head like, 'Oh, my God. I'm alive. This is so great.' " he said, referring to that first time back on his bike. "The other part of my brain is like, 'Just shut up. Just enjoy it. Whatever.' "

The disease came at a most inopportune time.

Murken, who had worked for nearly six years for the Nutter administration, was three months into a new boss - Mayor Kenney.

As the administration's legislative director, Murken was part of the team that crafted Kenney's groundbreaking tax on sweetened beverages. Kenney introduced the tax March 3 and from then on it was a whirlwind of preparing for the City Council hearings ahead, and then revising the legislation and making amendments.

In the middle of all that, Murken started to feel ill.

He assumed it was the flu and the day after Easter stayed home with a high fever, the chills, and an achy feeling.

The Suffern, N.Y., native also had pain in his right leg, which he assumed was just a sore muscle from biking. When a red and purple rash developed on his upper thigh, Murken called his primary-care physician, who prescribed antibiotics. He also asked Murken to draw a line to mark the upward reach of the rash.

On March 31, Murken woke up with the rash having spread above the line. He notified his doctor, who said he should go to the emergency room.

"He was in a tremendous amount of pain, even just walking to the car and then every bump we hit was really hard," Stephanie Baralecki, Murken's wife, said as she recalled driving him to Einstein.

Once Murken arrived at the hospital, doctors and nurses flooded him and ran various tests. After a CAT scan, an emergency-room doctor came out to tell Baralecki that her husband was very seriously ill.

" 'He's septic, his kidneys are failing, he's got necrotizing fasciitis,' " Baralecki quoted the doctor, who then wrote out the diagnosis on a white board.

"In case you want to Google it," he told Baralecki, who was reduced to laughter as she told the story at her kitchen table.

She did, and that's when she called a babysitter to stay overnight with the couple's children, Stephen, 8, and Rita, 5.

The first surgery went well and doctors were able to remove most of the bacteria. But more surgeries remained.

The clock was also ticking for the administration and the proposed soda tax.

When the hearings started, Murken was still in the hospital. To his frustration, he was forced to watch the hearings on the city's public-access channel.

"We would be the first major city in the country to get it done. This was big time," Murken said. "I hated not being there for it, just because it was such a thrilling thing."

For the next few weeks Murken focused on regaining his strength, walking again, and getting home to his family.

A few days after he was discharged, Murken went back to work. Although he was still in pain, he walked around City Hall with a cane and a wound-vac bag over his shoulder - the bag served as a suction to prevent his wound from getting infected.

"Getting better involved just kind of getting back to that stuff. . . . I wanted to be in there working on things," he said.

It is still a mystery how Murken ended up with flesh-eating bacteria. Usually the disease strikes older people with compromised immune systems. The bacteria often get in through a cut or other open wound, but Murken did not have either at the time.

Kaplan theorized that Murken must have had a small cut from bike riding. But Murken doubts it, given that the rash was just below his hip bone.

"It's like being struck by lightning," he said, describing the incident as random and rare.

People have asked him if he is scared of riding a bike again, given his doctor's theory.

He couldn't wait to get back on.

The first ride he was able to take was from his home to the Art Museum on a weekend in August.

"Here I am with two functioning legs going down Kelly Drive and back. It felt good," Murken recalled. "It was like a relief. My normal life is really back in view now."