A PROSPECTIVE-STUDY OF THE IMPACT OF COMMUNITY-BASED AZITHROMYCIN TREATMENT OF TRACHOMA ON CARRIAGE AND RESISTANCE OF STREPTOCOCCUS-PNEUMONIAE

In February 1995, single-dose azithromycin was given to children with trachoma and their household contacts who were children. For children with trachoma, rates of carriage of pneumococci immediately before tre atment with azithromycin and 2-3 weeks, 2 months, and 6 months after t reatment were 68% (54 of 79), 29% (11 of 38), 78% (29 of 37), and 87% (34 of 39), respectively. The proportion of carriage-positive children with azithromycin-resistant Streptococcus pneumoniae strains was 1 of 54 (1.9%) before treatment and then 6 of 11 (54.5%), 10 of 29 (34.5%) , and 2 of 34 (5.9%) at follow-up visits. The profile of pneumococcal serotypes changed after azithromycin treatment. Azithromycin-resistant strains (serotypes 10F, 23A, and 45) were isolated from 1 (1.3%) of 7 9 pretreatment swab specimens, from 16 (21.3%) of 75 swab specimens co llected up to 2 months after treatment, and from 2 (6%) of 32 obtained 6 months after treatment. Mathematical modeling showed a more rapid a ppearance of azithromycin-resistant pneumococcal strains in previously colonized children than in previously noncolonized children. Thus, it appears that the selective effect of azithromycin allowed the growth and transmission of preexisting azithromycin-resistant strains. More r esearch is needed to clarify the clinical relevance and implications o f azithromycin use.