I JUST LEARNED about the most ingenious recycling idea. It saves lives, reduces waste and appears to be easily replicable in other cities besides Philly, where it's kicking off this week.

Did I mention that it features babies and kittens? So it's also the most "adorable" reuse program in the city. Not that that's important, but it's a fun bonus when you're talking about something as workaday as recycling.

Let's start with those felines.

Each year, about 20,000 stray and abandoned cats - most of them kittens - are collected from the streets of Philly and brought to the city's animal shelters. The numbers peak in the summer months, when about 100 kittens per day are ferried into the shelter system.

Veterinarian Rachael Kreisler sees many of them. A lecturer at the Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania, she is working to expand its shelter-animal-medicine program, which brings veterinary students several days a week to city shelters to help provide care.

The most common medical problem among the kittens is eye trouble, Kreisler says. Viruses settle in the eye, causing significant infections that, left untreated, can rupture the eye, requiring removal. Or ulcers can form, leaving the eye permanently clouded.

"A kitten can do fine that way, but cosmetically, the kitten is disfigured. It's hard enough for us to find homes for so many kittens," Kreisler says. "If a kitten is disfigured, it's even harder."

And kittens who can't be placed in permanent or foster care have a greater chance of being euthanized, simply for lack of a place to put them.

The best line of treatment for kittens' eye problems is antibiotic ointment. But you can imagine the amount that's needed for so many kittens each year. The ointment isn't cheap, and a shelter needs so much that it can cost thousands of dollars. It can also be difficult to find, given recent drug shortages that plague veterinary medicine.

So, Kreisler was intrigued by a rumor that's been floating around the shelter community: namely, that hospitals with obstetric services throw away countless tubes of partially used antibiotic ointment - in this case, erythromycin - that's used on every human newborn to prevent birth-related eye infections.

Under certain conditions, the Food and Drug Administration allows the cross-use of approved human drugs in animals. Kreisler's research showed scant chance of cross-species contamination if pre-opened erythromycin tubes were used on kittens. Plus, the erythromycin used on human babies is of a gentler composition than the antibiotics she had been using on the kittens. So, her kittens would feel less discomfort.

Says Kreisler: "I knew that if we could get our hands on the ointment, we'd save thousands of dollars and thousands of kittens."

Through an acquaintance, she found Ryan Olivere, a clinical-nurse specialist on the labor and delivery floor of the Hospital of the University of Pennsylvania.

Olivere confirmed that, yes, each newborn at HUP is treated with a single-use tube of erythromycin and that there is medicine left in the 1-gram tube when it's discarded. And she loved the notion of sharing that leftover medicine with kittens in need.

But first she had to run the idea past HUP's regulatory department, to make sure that sharing was allowed, and with the pharmacy, to be sure that there was no chance that the kittens would be contaminated by the sharing.

Their response? Have at it.

And that's how, this week, Kreisler picked up her first batch of erythromycin tubes from HUP, where labor-and-delivery nurses have been depositing them in a designated box for pickup. Yesterday, Kreisler's students used the donated ointments for the first time on the shelter kittens.

"This is so wonderful!" says Kreisler. "HUP isn't the only hospital in the city that delivers babies. So, I know there's a lot more erythromycin we can be putting to use."

Olivere says that her nurses have responded enthusiastically to the program.

"I thought they might complain that this was one more thing they had to remember to do," she says of her busy staff, which handles about 100 deliveries a week. "But this has been very well-received. They drop the tubes in the box and say, 'I remembered the kittens!' This has tugged on everyone's heartstrings."

I wanted to know if Kreisler's idea was as novel as it sounded, but Andrea Ball, executive director of the national Association of Shelter Veterinarians wasn't able to answer my inquiry by deadline. An assistant there, though, was beside herself about it.

"Oh, oh, oh - that's amazing!" she said when I explained what Kreisler was up to. "What a great idea!"

It sure is.

Contact Ronnie Polaneczky at polaner@phillynews.com or 215-854-2217. Follow her on Twitter @RonniePhilly. Read her blog at philly.com/ronnieblog, or for recent columns go to philly.com/Ronnie.