 - Patients may not have any active infection requiring oral or intravenous antimicrobial therapy at the time of therapy initiation. Patients with a recent self-limited infection that has clinically resolved may complete a prescribed course of antimicrobial therapy after study initiation as long as they are asymptomatic with no clinical evidence of infection for at least 7 days prior to treatment. Patients with a recent serious grade 3 infection requiring hospitalization must have completed all antimicrobial therapy within 14 days of therapy initiation. 