Could anyone with a medical background please clarify the relationship between s!

Could anyone with a medical background please clarify the relationship between sulfa drugs and antibiotics?

I always thought antibiotics were one class of antibacterial and sulfa drugs (sulfonamides like Bactrim, not the sulfonylureas like glipizide) were different but all the info I keep looking up says sulfa drugs are antibiotics. Also, if you could help clarify the difference between the cillins (penicillin, amoxicillin, etc.) and the mycins (erythromycin, tetracycline, etc.) and how they relate to sulfa preparations that would be great. Do they all cause yeast infections? And if so, are there any preventive meds that stop a yeast infection if you have to take an antibiotic?
Thanks so much-I'm feeling really stupid now the more I try and understand this better)

4 days ago
thank you to both answerers so far. If you take Diflucan at the onset of antibiotic treatment will it still help prevent the yeast infections if your on them for 20 days-just got a Rx for Sulfamethoxazole/TMP DS for 20 days.

So antibiotics are divided into classes--they fight different types of bacteria and have different side effects. Sulfonomides (like bactrim) are but one class of antibiotics. Penicillin and amoxicillin are part of another class called beta lactams, and are safe for patients with sulfa allergies. Erythromycin and tetracycline are from two other classes of antibiotics (macrolides and tetracyclines, respectively) and are also safe for patients with sulfa allergies. All antibiotics can definitely cause yeast infections. If you often get yeast infections with antibiotics, most PCPs will give you a prescriptin for diflucan (a one time pill you can take for yeast infections with your antibiotic prescription). In terms of true prevention, the only thing I can recommend is one of the probiotic yogurts, like Activia by Dannon.