Statistical analyses.
To compare macrolide resistance in the treatment- and placebo-controlled arms, we tested for evidence of a significant difference in erythromycin resistance prevalence by using a permutation test for Using the same statistical techniques described above, we estimated prevalence differences for other common antimicrobials—clindamycin, penicillin, doxycycline, and trimethoprim-sulfamethaxazole.We also assessed whether resistance patterns consistent with suspected 