Abstract: Objectives To test a simple method for genotyping of C.trachomatis isolates and to investigate the clinical significance of the genotypes.Methods A part of the chlamydial genome encoding the major outer membrane protein(omp1) was amplified by polymerase chain reaction (PCR).The products were digested by endonucleases to see the characteristic patterns,after silver staining on 10% polyacrylamide gels.Results The omp1 genes of 15 serovars of C.trachomatis were amplified by PCR,which generated an 871 base pair gene fragment.AluⅠ digestion of the product gave characteristic patterns for the 15 serovars,but group C presented closely similar patterns.A triple digestion with HpaⅡ,followed by HinfⅠ and EcoRⅠ,would allow the differentiation of serovars in group C.Analysis of 74 clinical isolates revealed serovars E,F,D,G as the most prevalent genital serovars in the studied populations.Serovars B,H,J were occasionally identified.A mixed infection with serovars F and D was seen in a clinical sample.No significant relationship was observed between clinical manifestations of urogenital chlamydial infections and serovars,however,serovar D was more often associated with high titer of anti chlamydial antibody than other serovars.Conclusion The omp1 genotyping technique seems to be promising for epidemiological studies.

Key words: Chlamydia trachomatis, PCR, Genotyping