Iguana with sores and puss?

Question
Hello, thank you for taking the time to read this.  See my
girlfriend has a green iguana, named Sora, who is nearly
five feet long.  She takes great care of him; clean cage,
proper nutrition, the works!  But about a year ago he
started to develop a small sore on his back.  It looked like
a green scab and had a very sap-like quality to it.  She
thought perhaps he'd burned himself at first but she is very
careful about his heat lamps location so that wasn't it.  
She cleaned it but it din't get any better, only bigger!  
She took him to the vet and they said he was in excellent
health despite the sore and were very impressed at how well
she has raised him, it seems though he'd picked up some sort
of bacterial infection.  They recommended he come in for
weekly injections of antibiotic until it cleared up.  But it
didn't clear up.  After the first round of shots it seemed
to be healed.  But then it started to crop up elsewhere.  
She took him back to the vets and they gave him more shots
but it just doesn't seem to be working.  She is extremely
concerned for poor Sora, do you have any suggestions or
possible causes/treatment options?

Answer
Hi Katrina,
I suggest getting him to a vet for a skin scraping.  There has been a huge increase of a very nasty fungal infection called CANV (Chrysosporium anamorph of Nannizziopsis vriesii).
Many iguanas in captivity that have great care are coming down with this horrible disease.
Not much is written about iguanas with it, but here is a link to some info that you may want to pass on to your vet.  The article deals with bearded dragons.
http://biblio.ugent.be/record/887738
There is also a yahoo group called "Advanced Iguana Care" that has been discussing the disease.  I suggest joining that group and reading in the archives about the disease.
I wish your girlfriend the best of luck with getting Sora back to good health.