They and others in close contact with patients who have plague pneumonia or in direct contact with infected body fluids or tissues should receive oral prophylaxis for 7 days with Doxycycline 100 mg every 12 hours Ciprofloxacin 500 mg every 12 hours For children < 8 years, trimethoprim / sulfamethoxazole (TMP / SMX) 20 mg / kg (of the SMX component) every 12 hours Levofloxacin taken for 7 days is an alternative.