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Typing of Chlamydia trachomatis strains from urine samples by amplification and sequencing the major outer membrane protein gene (omp1).
Sexually Transmitted Infections 2001;77(6):419-422.
Bandea CI, Kubota K, Brown TM, Kilmarx PH, Bhullar V, Yanpaisarn S, Chaisilwattana
P, Siriwasin W, Black CM.
Abstract
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.