Chlamydia is a common sexually transmitted infection that can cause long-term complications and, in pregnancy, may cause adverse maternal and neonatal outcomes. Antenatal care provides opportunities for testing women from population groups with a high prevalence of the infection.
Chlamydia is caused by the bacterium Chlamydia trachomatis. Genital chlamydial infection remains asymptomatic in at least 70% of women and most infections probably clear spontaneously without morbidity. Complications that may arise for women include chronic pelvic pain, pelvic inflammatory disease, infertility and ectopic pregnancy.
40.1.1 Prevalence of chlamydia
- Rates of diagnosis: Chlamydia is the most frequently reported notifiable condition in Australia. The notification rate for chlamydia increased steadily between 2007 and 2011, remained relatively stable between 2011 and 2015 and increased by 8% in 2016 . Notifications have been higher in women than in men in all years (457.6 vs 364.3 per 100,000 in 2016). The rate of notification in the Aboriginal and Torres Strait Islander population has remained relatively stable since 2012 but in 2016 was more than three times that in the nonIndigenous population (1,193 vs 419 per 100,000) .
- Age: The trends in notification rates vary by age group. Among women, rates in the 15–19 year age group have declined (from 2,415 in 2011 to 1,932 per 100,000 in 2016), rates in the 20–24 year age group have remained relatively stable (2,265 in 2011 and 2,399 in 2016) and rates in the 25–29 year age group increased steadily between 2006 and 2016 (from 644 to 1,086 per 100,000) . The chlamydia notification rate in Aboriginal and Torres Strait Islander women aged 15–19 and 20–29 years in 2016 was four times and three times higher, respectively, than in the non-Indigenous population .
- Geographical distribution: After a steady increase in notifications between 2007 and 2011 in all jurisdictions, between 2012 and 2016 chlamydia notification rates were more stable, except in Queensland, where there was a steady increase (from 410.7 to 480.4 per 100,000). Chlamydia notification rates rose between 2015 and 2016 in New South Wales (14%) and Western Australia (7%) . Between 2012 and 2016, notification rates were highest and remained stable in remote and very remote regions (806.6 per 100 000 in 2016). Notification rates also remained stable in major cities in the same period (327.0 per 100 000 in 2016) but declined by 13% in inner and outer regional areas (419.5 to 367.2 per 100 000) . A similar pattern was seen in both males and females but in females there was a larger decline in inner and outer regional areas (16%) and rates also declined (11%) in the major cities.
Data on diagnoses of chlamydia are incomplete and may provide a distorted view of population rates in Australia. Differences in rates of diagnosis between areas and populations may reflect a range of factors, including variations in approaches to offering testing, access to services, and recording of Indigenous status.
40.1.2 Risks associated with chlamydia in pregnancy
Chlamydia infection during pregnancy has been associated with adverse outcomes including higher rates of preterm birth (OR 1.6; 90% CI 1.01–2.5) and intrauterine growth restriction (OR 2.5; 90% CI 1.32–4.18) . Left untreated, it has also been associated with increased low birth weight and infant mortality .
Babies born to mothers who have cultured positive to C. trachomatis, may subsequently also culture positive (approximately 25%) and have been reported to have higher rates of neonatal conjunctivitis, lower respiratory tract infections and pneumonia.
However, the NICE guidelines note that the causal link between chlamydia infection and adverse outcomes of pregnancy has not been established and the evidence remains difficult to evaluate in relation to neonatal morbidities .
40.2 Chlamydia testing in pregnancy
The NICE guidelines reviewed the evidence on diagnostic accuracy and effectiveness of testing methods in identifying genital chlamydia and found no good evidence to support routine antenatal testing.
40.2.1 Diagnostic accuracy
The evidence on diagnostic accuracy was limited to prospective cohort studies. The accuracy of antigen detection tests using endocervical specimens DNA probe test) may be accurate, the evidence is limited and of moderate quality . Based on limited evidence, Gram staining and Pap smear had insufficient accuracy to detect chlamydia.and of nucleic acid amplification tests using first-void urine and endocervical specimens was supported. While nucleic acid hybridisation test (
40.2.2 Effectiveness of testing
Review of the effectiveness of testing in reducing adverse outcomes for the pregnancy and the neonate found limited evidence (one RCT [ ] and five cohort studies [ ]) to indicate that treating chlamydia infection during pregnancy is effective in reducing the incidence of premature rupture of the membranes, preterm birth and low birth weight babies. There was no significant evidence to show that treating chlamydia infection during pregnancy leads to decreased incidence of adverse neonatal outcomes (conjunctivitis, pneumonia).
The literature review conducted to inform these Guidelines found no additional systematic reviews or RCTs to support or refute the findings presented in the NICE guidelines. However, there is additional information from systematic reviews and prevalence studies from 2008–2010 to suggest a specific population-based testing program (eg for those at highest risk). This evidence is discussed below.
40.2.3 Groups at higher risk
Antenatal care provides an opportunity to discuss chlamydia testing with young women. Other considerations before testing is offered include whether the pregnancy is unplanned, the number of recent male sexual partners and antibiotic use in the previous 3 months.
In the United Kingdom and the United States, chlamydia testing is recommended for pregnant women younger than 25 yearsand younger than 24 years , respectively. Testing of young women in Australia is supported by:
- the high prevalence of chlamydia in young people in Australia and modelling that predicts a reduction in prevalence through testing of people aged 25 years or younger
- estimates of the prevalence of chlamydia during pregnancy in young Australian women, which range from 3.2% (95% CI 1.8 to 5.9) among women aged 16–24 (n=403) (Chen et al 2009) to 13.7% among women aged 20 years or younger (n=212)
- qualitative research conducted as part of a prospective, cross-sectional study of pregnant women aged 16–25 years, which found a high level of acceptability of testing .
Do not routinely offer chlamydia testing to all women as part of antenatal care.
Approved by NHMRC in December 2011; expire December 2016 UNDER REVIEW
Routinely offer chlamydia testing at the first antenatal visit to pregnant women younger than 25 years.
Approved by NHMRC in December 2011; expire December 2016 UNDER REVIEW
While data are lacking to support routine testing, the prevalence of chlamydia is regionally variable and, in some areas, high prevalence may occur with that of other sexually transmitted infections, such as gonorrhoea. While testing of young women should take place in all areas, it is also important for health professionals to be aware of the rates of sexually transmitted infection in their community and develop local protocols accordingly.
Testing for chlamydia and other sexually transmitted infections regardless of age should be considered for women who live in areas where their prevalence is high. An understanding of local prevalence will inform planning for population testing when this is indicated.
Approved by NHMRC in December 2011; expire December 2016 UNDER REVIEW
40.2.4 Type and timing of test
As discussed above, antigen detection (eg nucleic acid amplification tests) are accurate in diagnosing chlamydia. Study of the acceptability of these tests to young woman found a preference for non-invasive methods. Both urine and vulval swab methods were highly sensitive, acceptable, and not affected by pregnancy status. However, women may be unable to produce urine on demand and unrefrigerated transport time has been reported to influence sensitivity of testing. There is also preliminary evidence that urine has the lowest organism load when compared to endocervical, self-collected vaginal, and urethral specimens.
40.3 Practice summary: chlamydia
At the first contact with women younger than 25 and women in high prevalence areas.
- Aboriginal and Torres Strait Islander health worker
- multicultural health worker.
- Discuss chlamydia
Explain the association between chlamydia and preterm birth and low birth weight, that tests for the infection are available and that it is easily treated with antibiotics.
- Take a holistic approach
If a woman tests positive for chlamydia, other considerations include counselling, contact tracing, partner testing, testing for other sexually transmitted infections and follow-up.
- Learn about locally available resources
Available testing services and support organisations will vary by location.
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