Frequency of Chlamydia trachomatis in Ureaplasma-positive healthy women attending their first prenatal visit in a community hospital in Sapporo, Japan

Abstract

Background: Although Chlamydia trachomatis is the most commonly reported pathogen that causes urogenital infection such as urethritis or cervicitis, Ureaplasma parvum and Ureaplasma urealyticum, which are commensals in the genital tract, have also now been recognized as contributors to urogenital infection. However, whether the presence of either U. parvum or U. urealyticum is related to that of C. trachomatis in the urogenital tract remains unknown. We therefore attempted to estimate by PCR the prevalence of C. trachomatis, U. parvum and U. urealyticum in endocervical samples obtained from healthy women attending their first prenatal visit in Sapporo, Japan.

Methods: The samples were taken from 303 apparently healthy women, and the extracted DNAs (n = 280) were used for PCR detection targeting C. trachomatis, U. parvum and U. urealyticum. Statistical analysis of the data was performed by Fisher's exact test.

Results: PCR detection revealed that the prevalence of C. trachomatis, U. parvum and U. urealyticum was 14.3% (40/280), 41.7% (117/280) and 8.9% (25/280), respectively. C. trachomatis ompA genotype D was most frequently identified. Surprisingly, either C. trachomatis or Ureaplasma spp. was detected in almost half of the healthy women. Mixed infection of C. trachomatis with either U. parvum or U. urealyticum was also observed in 9.2% (26/280) of the women. There was a significant association between C. trachomatis and either U. parvum (p = 0.023) or Ureaplasma total (p = 0.013), but not U. urealyticum (p = 0.275).

Conclusion: This study demonstrated that the presence of Ureaplasma had a significant effect on the presence of C. trachomatis in the genital tract of healthy women, suggesting that mixed infection is an important factor in bacterial pathogenesis in the genital tract.

Figure 1

Representative PCR detection images showing C. trachomatis, U. parvum and U. urealyticum amplification. N, negative control (molecular grade water); P, positive control (DNA extracted from each of the bacteria).

Figure 2

Detection frequencies of C. trachomatis, U. parvum and U. urealyticum in DNA extracted from genital swabs.

Figure 3

Phylogenetic trees showing the relationships between C. trachomatis ompA PCR amplicons and previously identified bacterial sequences. Orange letters (B, D-G and I-K), ompA genotypes. Parenthetical percentages, the prevalence of each of the ompA genotypes. Up (blue letters), U. parvum. Uu (purple letters), U. urealyticum. Undetermined, these samples failed to amplify ompA gene fully because of DNA degradation.