When multiple otopathogens were simultaneously present in the NP at the time of AOM the culture-positive rate in MEF was compared using logistic regression with repeated measures and Fisher's exact test. The percentage of each otopathogen causing AOM when co-colonization occurred involving, A, Spn with Hflu; B, Spn with Mcat; C, Hflu with Mcat; D, all three otopathogens; E, 19A or non-19A strains of Spn with Hflu; B, 19A or non-19A strains of Spn with Mcat. NP: Nasopharynx; MEF: middle ear fluid; Spn, S. pneumonia; Hflu: H. influenzae; Mcat: M.catarrhalis.