Can an untreated bacterial infection turn into a std if my partner and i continue to have sexual contact before infection is treated?

STD risk, avoid sex: Whatever kind of "bacterial infection" you have, it won't become something different, either an STD or otherwise. You may already have an STD. "Bacterial infection" of the vagina usually means bacterial vaginosis, and STDs (gonorrhea, chlamydia, etc) are more common in women with BV. Best to avoid sex, and both you and your partner get medically evaluated. If sex can't be avoided, use condoms.