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Detection and genotyping of Chlamydia trachomatis in clinical urogenital samples from north-eastern Croatia

Due to the chronic and “silent” infection and variable antigenic structure of the Chlamydia trachomatis we supplemented Direct Immune Fluorescence with the molecular diagnostic method using COBAS TaqMan 48 real time PCR instrument. The fast molecular diagnostics of C. trachomatis infections and adequate therapy of the infected individuals are the crucial step in the C. trachomatis spread control. The epidemiological data obtained from the Osijek-Baranja County Institute of Public Health archives revealed the true number of chlamydia genital infections among other genital infections in the last five years in our county. The aim of the present study has been to reveal the most prevalent serotype of the C. trachomatis detected in urine and gynaecological samples in the population of the Osijek–Baranja County and to monitor the infection and the therapy efficiency. The determined serotype distribution has been compared with the C. trachomatis distribution pattern in other regions of the World. All the samples were collected from the Osijek-Baranja County Institute of Public Health and gynaecologist's offices. Methods: COBAS TaqMan CT test is an in vitro nucleic acid amplification test which utilises real time PCR technology. The test has been developed to confirm analogous detection of all 15 C. trachomatis serotypes and it produces results within 3 hours. Subsequently all the positive samples have been analysed directly by sequencing of the amplified omp1 fragments using Applied Biosystems 3130 Genetic Analyser. Genotyping and sequence mutation analysis have been performed by BLAST searching and compared with the reference sequences of all known C. trachomatis serotypes. Results: The most prevalent genotype in Osijek- Baranja County was serotype E (in agreement with Sweden and Taiwan data), followed by F, G, D, K, J, H, B, and Ia (differs from Sweden and Taiwan data). The sequence of omp1 gene showed limited variation. Conclusion: The obtained omp1 gene genotyping results could be useful tool for epidemiological characterisation of circulating C. trachomatis in our community. Further analyses in this ongoing project might also reveal the influence of certain serovar on clinical signs, intensity of infection, duration of genitourinary infection considering age and sex and therapy efficiency, as well as possible presence of chlamydial coinfection and reinfection.

C. trachomatis; omp1 gene; urogenital infections; serotypes; Osijek-Baranja County

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