Cat vs cat injury

I have two sisters, calicos, attitude a plenty! THey love on eachother, groom, play, then will give eachother grief in hissyfit fasion.
Now big sister has a scab she wont let me check out, on the neck behind her ear. They have never fought to hurt before.
Should I be worried about infection?
From what I have seen, it does not look bad, but I know cat bites to humans can cause trouble. Is it the same for for them?

I have four cats under the age of 2 and it happens pretty regular. What I have found to be the easiest is to check on wounds while they are eating or cuddled in my lap. Usually if they are eating they will sit still long enough for me to check the wound and put some neosporin on it. I start with the neo on my finger first so they don't see the tube and go for the quick swipe on the wound. If it's just a scab you are probably ok, if it's not hard then you need to irrigate it and keep a closer eye on it. I use a solution I got from the vet to clean it and then try to get some neo on it. Kittens and cats play rough with each other but seem to heal pretty quick. If you see hair loss around the wound that is another indicator that you need to keep a close eye as well.