What are the effects of ampicillin for acne?

It works if indicate: We do not use Ampicillin these days as it has to be taken 4 times a day.So we use Amoxicillin which can be taken only twice a day.It takes three weeks to see positive effect, and three months to see full effect.But long term use can cause bacterial resistance.It should be used with local therapy with benzyl peroxide and retinoids locally, and can be followed with topical antibiotics.