57. GENOTYPING OF UROGENITAL CHLAMYDIA TRACHOMATIS IN REGIONAL NEW SOUTH WALES, AUSTRALIA

Abstract

Background: Chlamydia Trachomatis is one of the most common sexually transmitted infections in Australia and world wide. This study was undertaken to map the frequency of Chlamydia genotypes in regional New South Wales (NSW), Australia, to explore the potential utility of genotype analysis in defining local sexual networks, and to investigate whether patterns of genotype frequency are correlated with demographic factors, including age and gender.

Methods: We studied 204 urine samples infected with Chlamydia trachomatis, as determined by PCR analysis using the COBAS Amplicor system. Samples were collected from wide geographic area of regional New South Wales (Hunter, New England, Northern Rivers, South Eastern New South Wales). Sequencing and genotyping were performed after nested PCR of the omp1 gene.

Results: Genotype E was found in 42.6% of infections, with genotypes F (23.5%) and G (16.7%) other common causes of infection. Mixed infection occurred in only 3 cases. There was no significant difference in genotype frequency based on gender or geographic location. There was a significant difference in gender frequency based on patient age, with older patients significantly more likely to demonstrate infection with genotype G (mean age (years) 23.7+/-7.29 sd, E: 21.7 +/-5.7 sd; G: 28.9; sd 10.18; p = 0.022).

Conclusions: There was no significant difference in genotype frequency in the various regions of New South Wales, suggesting genotype analysis is of limited use in defining sexual networks in regional NSW. The finding of a higher frequency of genotype G in older patients raises the possibility that genotypic variation may be driven by immune responses to genotypes that occur more frequently at a younger age. These results may have implications for the future design of a chlamydial vaccine.