Problems associated with serotyping strains of Ureaplasma urealyticum

We sought to identify problems associated with serotyping Ureaplasma urealyticum, a human genital tract mycoplasma. We examined the results of serotyping isolates from cases of nongonococcal urethritis and asymptomatic controls and found no indication of correlation between serotype(s) and pathogenic potential. Reproducibility in serotype determination was generally good, i.e., overall agreement of 83% between primary and secondary plating and 87% on multiple, secondary cultures. We examined the reasons for variation in reproducibility and also the selection of a minor antigenic component in a culture. We provide no evidence of changes in the antigenicity of an isolate. We have indicated the means for standardizing reagents and the interpretation of results and have suggested improvements in methodology to allow more objective serotype determination.