PHOENIX - At Banner Estrella Medical Center, there's an infection making its way around the campus. An infection with a distinctive sound and personality -- what some might call an infectious personality, the kind that comes with a bright, flashy smile, and a song to match.

The kind of song like, "You Are My Sunshine," that Telma Medina sings to dozens of patients every day. Follow her around as she makes her deliveries and it's easy to see how her songs are a sure-fire cure to chase away the blues.

"Some of the patients, when they're here, they feel alone 'cause they're in a room, their family members are at work and they can't be here," Medina said. "If I sing, that makes them happy."

Medina has been working in hospitals for the past 23 years, the last 12 at Banner Estrella as a room service hostess serving patient meals. All day long, she loads up her cart with delicious food and a ton of positive energy.

"We're Banner soldiers, and Banner soldiers never give up!" she said as pushed another cart of meals onto an elevator.

For the past seven years, this soldier's weapon of choice has been about a dozen songs.

"I just started doing it just naturally, 'cause this is my happy place," Medina said.

She is the first to admit that her voice can be annoying at times, but not to any of the patients she serves.

"She's always singing, always humming a tune," Diana Garcia, a patient at Banner Estrella said. "She just lights up your life."

The refrain, "Please don't take my sunshine away" could be heard coming from Garcia's room as Medina dropped off her lunch.

Medina's singing is well received around the hospital. She says if she's not singing, people will stop and ask her, "What's wrong?" She confessed that snaps her right back into another song, and she's back in her happy place.