Results

1. CHARACTERIZATION OF CHLAMYDIA TRACHOMATIS OMP1 GENOTYPES IN A SWEDISH COUNTY 2006 AFTER THE FINDING OF THE NEW VARIANT (nvCT) COMPARED TO THE GENOTYPE DISTRIBUTION IN THE SAME AREA 1999 TO 2000 MargarethaJurstrand1, 2, Hans Fredlund2, Per Olcén2, Magnus Unemo2 Clinical Research Centre1, Department of Clinical Microbiology2, Örebro University Hospital, SE-70185 Örebro, Sweden Objecives A newChlamydia trachomatis variant (nvCT) was recently reported in Sweden. The variant contains a 377 bp deletion in the cryptic plasmid (1) that includes the target for the diagnostic system (Cobas Amplicor, Roche Diagnostics) used in Örebro County, Sweden. The aims of this study were to characterize C. trachomatis omp 1 genotypes in Chlamydia tissue culture positive samples, collected from October to December 2006, and to compare with the results of a one year study performed from 1999 to 2000 in the same area (2) Material and Methods Consecutive Chlamydia tissue culture positive samples (n = 100), including 40 samples of the new variant (Cobas Amplicor negative and mutant-specific real-time PCR positive), were genotyped using C. trachomatisomp1 gene amplification and sequencing as previously described (2) Results In total, genotype E was significantly more prevalent (69.0%; p < 0.001) in consecutive samples from 2006 (Figure 1)compared to 47.3% in 1999 – 2000 (Figure 2). All 40 samples of the C. trachomatis new variant (nvCT) were of identical genotype E. However, the distribution of genotypes among the Cobas Amplicor positive samples (n = 60) was similar to the distribution in the material from 1999 to 2000 (Figure 3). Further characterization using multilocus sequence typing with a higher discriminatory capacity than omp1 gene sequencing is in progress. Figure 2 Figure 1 Conclusions The proportion of the new C. trachomatis variant was very high (40%). All isolates were of identical genotype E and seem to originate from a single transmitted clone (3). Presently, it is unknown when and where this C. trachomatis variant appeared and started to be transmitted. However, in the study from 1999 to 2000 one suspected variant, which was determined as genotype E, positive in omp1 gene PCR but repeatedly negative in Cobas Amplicor, was identified. Figure 3 References 1. Ripa, T and Nilsson, P. A Chlamydia trachomatis strain with a 377-bp deletion in the cryptic plasmid causing false negative nucleic acid amplification tests. Sex Transm Dis 2007. 34:255-56 2. Jurstrand, M. et al.Characterization of Chlamydia trachomatis omp1 genotypes among sexually transmitted disease patients in Sweden. J Clin Microbiol. 2001. 39:3915-9 3. Unemo, M. et al. Experiences with the new genetic variant of Chlamydia trachomatis in Örebro county, Sweden – proportion, characteristics and effective diagnostic solution in an emergent situation. Euro Surveill. 2007. 12 (4) e-mail: margareta.jurstrand@orebroll.se