I don't have a tube in front of me, so take this with a bit of salt. Neosporin is bacitracin, neomycin, and polymyxin B. These are all feline safe. However, the bits that make the medicine stable as a gel can be very unpleasant for the cat. If the bite is on the neck or face where the cat won't directly ingest, you should be fine. Just watch for signs of a foamy lip or lots of drinking, this means the cat got some on his tongue and thinks it tastes awful. A warm compress for 10 min two to three times daily can do a lot to help the wound. Please also be aware that salt water flush can impede healing, depending on osmotic properties.
The issue with cat bites is that they go so deep that a topical abx really won't touch the deep infection. For that, you'll need an oral antibiotic. If cost is an issue, many human side pharmacies now have free or very low cost antibiotics. You may be able to skate by with just a quick office call and a paper prescription.Here is a link
to the handout we give for our clients. Be warned, there are photos, so you might want to put your coffee down if you're squeamish.
(*I'm not your vet, and this isn't medical advice*)