Typing of Chlamydia trachomatis strains from urine samples by amplification and sequencing the major outer membrane protein gene (omp1)

Objectives: To develop a novel protocol for the extraction, amplification, and sequencing of Chlamydia trachomatis MOMP gene (omp1) from urine, a non-invasive source, and apply it to an epidemiological study on the distribution of C trachomatis strains in a population of pregnant women in Thailand. Methods: The C trachomatis DNA was extracted from culture stocks and urine using a slightly modified commercially available kit, the High Pure PCR Template Preparation Kit (Roche Molecular Biochemicals, IN, USA). The PCR and sequencing primers used for the amplification and sequencing of the omp1 were designed based on the nucleotide sequence of multiple C trachomatis strains found in GenBank. The protocol for the extraction, amplification, and sequencing was tested on laboratory culture stocks of reference strains of all C trachomatis serovars and on urine samples collected in a cross sectional study designed to assess the prevalence of C trachomatis infections in the cities of Bangkok and Chiang Rai, Thailand. Results: The omp1 gene was successfully amplified and sequenced from 18 laboratory C trachomatis reference strains and from 45 C trachomatis positive urine clinical samples collected from asymptomatic pregnant women. Among clinical samples, we found nine different C trachomatis genotypes: F (11, 25%), D (10, 22.6%), H (5, 11.7%), K (5, 11.7%), E (4, 9.3%), Ia (3, 7%), B (3, 7%), Ja (2, 4.5%), and G (1, 2.3%). One specimen generated an omp1 DNA sequence pattern indicating the presence of a mixed infection with at least two different serovars. Conclusions: Urine is a convenient and reliable source for genotyping C trachomatis strains. A clear advantage of urine over traditional samples, such as cervical swabs, is that urine is a non-invasive source which makes collection easier and thus facilitates the enrolment of patients in clinical and epidemiological studies. In addition to typing, urine is increasingly used for diagnosis of C trachomatis infection by several commercially available nucleic acid amplification assays which represents a distinct advantage for collecting, transport, storage, and laboratory handling of samples. Key Words: genotype; Chlamydia trachomatis; urin

Guidelines for the Management of HIV Infection in Pregnant Women and the Prevention of Mother-to-Child Transmission of HIV

The prevalence of HIV infection amongst women giving birth in England and Wales has increased every year since 1990. Results from the Unlinked Anonymous Surveys of infection in pregnancy, show that in 2003, the prevalence reached one in 180 (0.56%) in inner London, one in 271 in outer London (0.37%) and one in 1,282 (0.08%) in the rest of England [1]. The majority of these women are from sub-Saharan Africa. The Department of Health policy of recommending an HIV test to every pregnant woman [2] has resulted in an increase in the proportion of these women who are aware of their diagnosis prior to delivery (more than 80% in London in 2001) and a decrease in the absolute number of infants infected in the UK [3]