Examples of antibiotics that are effective are Trimethoprim / sulfamethoxazole 160 mg/800 mg orally twice a day Amoxicillin 250 to 500 mg orally 3 times a day Doxycycline 50 to 100 mg orally twice a day Azithromycin 500 mg orally once a day Choice of drug is dictated by local patterns of bacterial sensitivity and patient history.