Sexual Health

Casper D.J. den Heijer, MD, on How Chlamydia trachomatis Infection Affects Reproductive Health Outcomes

Women with positive tests for Chlamydia trachomatis are at an increased risk of pelvic inflammatory disease (PID), ectopic pregnancy, and female infertility, according to findings from a new study.1

The study was led by Casper D.J. den Heijer, MD, who was researcher in the Division of Pharmacoepidemiology and Clinical Pharmacology at Utrecht Institute of Pharmaceutical Sciences and is a doctor in infectious disease control in the Department of Sexual Health, Infectious Diseases and Environmental Health, at the Public Health Service South Limburg in Heerlen, Netherlands.

After reviewing C trachomatis test results from 857,324 young women (aged 12-25 years) in the Clinical Practice Research Datalink GOLD database, Dr den Heijer and colleagues found a 2.36-fold increased risk of PID, a 1.87-fold increased risk of ectopic pregnancy, and a 1.85-fold increased risk of infertility among women with a positive test vs a negative test.

Consultant360 caught up with Dr den Heijer to find out more about these outcomes.

C360: Your team found that the risk of PID was higher among women with 2 or more positive tests for C trachomatis vs those with 1 positive test. What does this finding say about the long-term effects of C trachomatis? What is the role of repeat infections?

Dr den Heijer: This finding indicates a dose-response relationship between C trachomatis positivity and PID, and thereby gives additional evidence that a causal relationship could exist between these 2 conditions. Women with more C trachomatis infections in time have a higher chance of PID. Hence, our results confirm the reproductive health burden of C trachomatis and show the need for adequate public health interventions (enhanced testing efforts in at risk groups) against C trachomatis, as still many C trachomatis infections are hidden to adequate diagnosis and treatment.   

C360: Another finding of your analysis showed that current and recent antibiotic use affected the risk of PID in women with C trachomatis infection. What is the connection between antibiotics and the risk for PID?

Dr den Heijer: Our assumption was that C trachomatis–effective antibiotics prescribed for other conditions than C trachomatis would “incidentally” treat asymptomatic C trachomatis infections. With the association between C trachomatis and PID, these “incidental” treatments would lower the risk of PID. In our study, we could not confirm this assumption. Possible explanations were given in the Discussion section of our paper: “Possible explanations for the positive association between PID and [C trachomatis]-effective antibiotic prescriptions could be that PID can be caused by other infectious diseases that could be treated with [C trachomatis]-effective antibiotics; for example, Mycoplasma genitalium with azithromycin as the treatment of first choice.”1

C360: For women with C trachomatis, what approaches might lower their risk for PID, ectopic pregnancy, and infertility?

Dr den Heijer: Our findings provide evidence that women with a positive C trachomatis test registered at the general practitioner have a higher risk for adverse reproductive health outcomes. Adequate treatment with antibiotics needs to be provided in the individual patient with attention to potential reinfection. Therefore, partner management and testing for repeat infections after 4 to 6 months should be in place at each general practitioner and at sexually transmitted infections clinics.

C360: In your opinion, what has to be done to better care for this patient population, and who must be involved to reduce this health burden?

Dr den Heijer: In addition to my previous answer, an issue on adequate antibiotic treatment remains, as our research group has reported in other studies, detection of C trachomatis after treatment with first-choice azithromycin and not with doxycycline.2,3,4 As in most women, genital infection co-occurs with an anorectal C trachomatis infection, doxycycline might be a better choice.


  1. den Heijer CDJ, Hoebe CJPA, Driessen JHM, et al. Chlamydia trachomatis and the risk of pelvic inflammatory disease, ectopic pregnancy, and female infertility: a retrospective cohort study among primary care patients. Clin Infect Dis. 2019;69(9):1517-1525.
  2. van Liere GAFS, Dukers-Muijrers NHTM, Levels L, Hoebe CJPA. High proportion of anorectal Chlamydia trachomatis and Neisseria gonorrhoeae after routine universal urogenital and anorectal screening in women visiting the sexually transmitted infection clinic. Clin Infect Dis. 2017;64(12):1705-1710.
  3. Dukers-Muijrers NHTM, Wolffs PFG, de Vries HJC, Götz HM, Janssen K, Hoebe CJPA. Viable bacterial load is key to azithromycin treatment failure in rectally Chlamydia trachomatis infected women (FemCure). J Infect Dis. 2019;220(8):1389-1390.
  4. Dukers-Muijrers NHTM, Wolffs PFG, de Vries H, et al. Treatment effectiveness of azithromycin and doxycycline in uncomplicated rectal and vaginal Chlamydia trachomatis infections in women: a multicentre observational study (FemCure) [published online January 28, 2019]. Clin Infect Dis.


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