Mass Antibiotic Treatment for Group A Streptococcus Outbreaks in Two Long-Term Care Facilities1
Figure 2. Epidemic curve for outbreak 1. Clinical cases (black bars) of invasive GAS infection occurred at intervals of 3 to 4 months. With the occurrence of cases, acquisition of culture specimens resulted in identification of asymptomatic colonization with the outbreak strain (white bars) or unrelated strains (hatched bars) in other residents and staff. No additional clinical cases occurred after mass antibiotic treatment (M.A.T.); resident A died (†) in July 2002; colonization of two residents with the outbreak strain was recognized 1 month later.