Rectal chlamydia infection in women at high risk of chlamydia attending Canberra Sexual Health Centre

Abstract

Chlamydia is the most commonly notified sexually transmitted infection in Australia. Australian guidelines recommend urogenital screening in asymptomatic men and women, and rectal screening in men who have sex with men or women reporting anal sex/symptoms. International studies describe a rectal chlamydia prevalence in women of 5% to 21%. We found that in women at high risk of chlamydia, 57% (32/56) tested positive for rectal chlamydia. Of these, 97% (31/32) had concurrent urogenital chlamydia. Women with urogenital chlamydia were significantly more likely to have a positive rectal result (χ², p = 0.000). Neither anal symptoms nor reported anal sex were associated with a positive rectal chlamydia test. The recommended treatment of rectal chlamydia differs substantially from that of urogenital chlamydia, raising the possibility that Australian women are being regularly undertreated due to a lack of rectal testing. Untreated rectal chlamydia may increase the risk of persistent infection, reproductive tract reinfection, complications and transmission. Further work is needed to determine the optimal management of chlamydia in women.

Keywords

Chlamydia rectal extragenital women screening public health Australia

Introduction

Chlamydia is a sexually transmitted infection (STI) caused by Chlamydia trachomatis, an intracellular bacterium that can infect genitourinary, oropharyngeal and rectal sites.¹ Chlamydia is the most common notifiable STI in Australia, with a national notification rate of 359/100,000 population.² Whilst many men experience symptoms of urethritis, and less commonly epididymitis or orchitis, the majority of female genitourinary infections are asymptomatic.¹ Persisting cervical infection can result in serious complications, including pelvic inflammatory disease (PID), fallopian tube scarring, ectopic pregnancy and infertility.¹ Rectal symptoms are rare in both genders, with up to 86% of male³ and 100% of female^4–10 infections being asymptomatic at this site.

Australian Guidelines recognise the risk of rectal chlamydia carriage in men who have sex with men (MSM), recommending yearly screening, or more frequently where there are additional risk factors.^11,12 The prevalence of rectal infection in MSM is 4% to 9%^2,13 and 5.6% in Australia.¹⁴ Rectal infection is more common than urogenital infection in MSM,^13,14 and more than half of all chlamydia in this group would go undetected in the absence of anal screening.³

Women are not routinely offered rectal screening, despite evidence of frequent and increasing participation in anal intercourse.^4,8,9 Australian guidelines recommend rectal testing in women only where there are anal symptoms, where anal sex is reported, or in the case of sexual assault with anal penetration.¹¹ The prevalence of rectal chlamydia in women has been reported as 5–18% in the USA,^4,8,15 5–21% in the UK,¹⁶ 12–14% in Canada,⁵ 5–9% in the Netherlands^6,9,17,18 and 7% in South Africa.⁷ Studies of women attending STI clinics have reported rates of 5–12%^4–7,17,18 whilst those investigating women reporting anal intercourse, rectal symptoms, sex work, sexual assault or drug use have returned values in the range of 7–18%.^2,8,9,16 No Australian data are available.

Studies investigating risk factors for rectal chlamydia in women have identified genitourinary chlamydia or gonorrhoea, and younger age, as risks.^4–8,15,16 An association with recreational drug-use has been reported in older women.¹⁵ History of anal sex, rectal symptoms, multiple recent sexual partners, commercial sex work, overseas travel, incarceration, history of STIs, race and income have not shown a significant association.^4–9,15,18

This study aimed to determine the incidence of rectal chlamydia in a set of high-risk Australian women, and to assess possible risk factors for rectal chlamydia that might guide future screening protocols.

Methods

Study population

Women attending Canberra Sexual Health Centre (CSHC) from November 2013 to June 2014 who presented (1) for treatment and follow-up of laboratory-confirmed urogenital chlamydia including test-of-reinfection three months post treatment, (2) with symptoms consistent with urogenital chlamydia or PID or (3) as a sexual contact of someone diagnosed with chlamydia were invited to take part in the study. Women who agreed to participate supplied written consent, were asked to complete a questionnaire and to provide samples to be tested for rectal and urogenital chlamydia. Their management was otherwise as per CSHC routine practice.

Questionnaire

Study participants were asked to provide details regarding demographics (age and country of birth), sexual preference (heterosexual, bisexual, lesbian, transgender, intersex); sexual partners (number of men and women partners in the preceding six months, whether they had a current partner, duration of that relationship and whether partner/s engaged in sex with men); sexual practices (vaginal, oral and/or anal sex in the prior six months, whether condoms/dental dams were used and how frequently, whether they had ever engaged in anal intercourse and date of last unprotected occasion, frequency and type of anal play (nudging with penis, fingering around the anus, digital penetration), frequency and anatomical site of sex-toy use (mouth, vagina, anus) and whether condoms were used); history of chlamydia screening (at any site and rectally, reason for, and number of, previous tests); previous chlamydia infection/s (number and site); rectal symptoms (pain, itch, discharge, bleeding and tenesmus); and other potential risk factors (whether the respondent or any sexual partner had ever been incarcerated, used intravenous drugs or other recreational drugs).

File review

Additional demographic data (occupation, whether identified as an Aboriginal and/or Torres Strait Islander) and clinical information (reason for presentation and results of chlamydia testing) were extracted from the patient’s clinical file, as per their written consent.

Chlamydia testing

All participants self-collected a rectal swab. Women who had not previously done so were also asked to provide a first-catch urine specimen or a self- or clinician-collected vaginal or cervical swab to be tested for urogenital chlamydia. All samples were processed by ACT Pathology using the Roche COBAS Amplicor Assay.

Data analysis

All data analysis was carried out using STATA (Version 10).

Results

Fifty-six women meeting the inclusion criteria were enrolled and correctly completed the questionnaire. Participants were aged between 15 and 54 years, 79% were born in Australia and 5% identified as Aboriginal or Torres Strait Islander, 43% were students, 38% were employed and 11% reported either home-duties or unemployment (Table 1). None reported having only women partners.

Table 1.

Rate of rectal chlamydia by demographic and sexual history variables.

	Number in sample (%)	Proportion with positive rectal result (%)	Significance χ²
Age group
15–19 years	18 (32)	13/18 (72)	−
20–24 years	21 (38)	11/21 (52)	ns
25+ years	16 (29)	8/16 (50)	ns
Occupation
Student	24 (43)	17/24 (71)	−
Employed	21 (38)	11/21 (52)	ns
Unemployed/home-duties	6 (11)	2/6 (33)	ns
Not stated	5 (9)	2/5 (40)	na
Country of birth
Australia	44 (79)	26/44 (59)	−
Overseas	11 (20)	5/11 (45)	ns
Not stated	1 (2)	1/1 (100)	na
Aboriginal and Torres Strait Islander status
Yes	3 (5)	3/3 (100)	−
No	34 (61)	19/34 (56)	ns
Not stated	19 (34)	10/19 (53)	na
Sexual orientation
Heterosexual	47 (84)	27/47 (57)	−
Bisexual	7 (13)	3/7 (43)	ns
Not stated	2 (4)	2/2 (100)	na
Number of sexual partners previous six months
Less than two	26 (46)	7/26 (27)	−
Two	16 (29)	4/16 (25)	ns
Three or more	14 (25)	4/14 (29)	ns
Anal intercourse
Yes, less than six months ago	19 (34)	11/19 (58)	−
Yes, more than six months ago	15 (27)	6/15 (40)	ns
No, but engages in anal play	11 (20)	8/11 (73)	ns
No anal sex and no anal play	11 (20)	7/11 (64)	ns
Frequency of condom use for anal intercourse
Always uses condoms	5 (9)	1/5 (20)	−
Mostly/ sometimes/ hardly uses	9 (16)	6/9 (67)	ns
Never uses condoms	20 (36)	10/20 (50)	ns
Has never had anal sex	22 (39)	15/22 (68)	na
Sex toy use
Yes, in/around anus	3 (5)	1/3 (33)	−
Yes, site other than anus	19 (34)	13/19 (68)	ns
Yes, site not specified	5 (9)	2/5 (40)	ns
No	29 (52)	16/29 (55)	ns
Rectal symptoms
Yes	7 (13)	2/7 (29)	−
No	49 (88)	30/49 (61)	ns
Drug use or history of incarceration
Self
Yes	17 (30)	7/17 (41)	−
No	39 (70)	25/39 (64)	ns
Partner
Yes	26 (46)	13/26 (50)	−
No	30 (54)	19/30 (63)	ns

-: Baseline group; ns: not significant (p > 0.05); na: not applicable (excluded from comparison).

A total of 77% percent of participants had positive urogenital results and 57% had positive rectal chlamydia swabs. Of those with positive rectal tests, 97% (31/32) had concurrent urogenital chlamydia. Women testing positive for urogenital chlamydia were significantly more likely to test positive at the rectum than women without urogenital infection (χ², p = 0.000; Table 2).

Table 2.

Number, proportion and percentage of women with rectal chlamydia and rate of urogenital (UGT) co-infection, by reason for presentation.

	Total rectal positive	Rectal + UGT positive	Isolated rectal positive	Isolated UGT positive
Presentation type	Proportion of total (%)	Proportion of rectal positives (%)		Proportion of total (%)
Treatment/follow-up	20/25 (80)	20/20 (100)	0/20 (0)	5/25
Contact	10/17 (59)	9/10 (90)	1/10 (10)	1/17
Symptoms	2/14 (14)	2/2 (100)	0/2 (0)	1/14
Total	32/56 (57)	31/32 (97)	1/32 (3)	7/56 (13)

Follow-up: women enrolled at follow-up for recently diagnosed urogenital chlamydia infection or presenting 3 months post treatment for a test of cure; contact: women who presented as a contact of chlamydia infection; symptoms: women presenting with symptoms suggestive of urogenital chlamydia or pelvic inflammatory disease.

There was no significant difference in rectal chlamydia (χ², p > 0.05) by age, employment, ethnicity, sexual orientation, number or partners, anal sex history, sex-toy use, symptoms or drug use/incarceration (self or partner; Table 1).

Discussion

This study demonstrated a substantially higher rate of positive rectal chlamydia results in women than previously reported in a range of other countries,^{2,4–9,15–18} and over three times higher than that reported in women identified as high-risk by a range of criteria.^2,8,9,16 Our finding that positive urogenital testing is associated with positive rectal testing, whilst past history of anal sex and rectal symptoms are not, is consistent with previous reports.^5–8

The relatively high prevalence of positive rectal chlamydia results in this study likely reflects the much greater burden of genitourinary chlamydia selected in our study participants (67% vs 5.4–16%^{4–7,9,15–18}). The design of this study deliberately selected women with known chlamydia infection, or at high risk of chlamydia infection through sexual contact with another person known to have chlamydia, or symptoms consistent with chlamydia.

The lack of association between rectal chlamydia infection and history of anal sex could reflect under-reporting of anal sexual activity. However, in our study 80% of women reported a history of anal sex or anal play; 34% reporting anal sex in the past six months, 27% anal sex more than six months ago, 20% any anal play and 5% the use of sex toys in or around the anus. Alternatively the rectum in women may become infected through the natural tracking of either semen or vaginal secretions to the rectum.^{4–7,9,15–19} Another possibility is that the positive rectal tests reflect contamination of the swab with vaginal secretions during the sampling process rather than true rectal infection. Given that our specimens were patient-collected it is difficult to estimate the likelihood of cross-contamination. However, one of the women enrolled in our study had an isolated rectal chlamydia, whilst another remained positive in the rectum but not the vagina following treatment with a single 1-g dose of azithromycin, so not all positive rectal results can be explained by cross-contamination by vaginal secretions.

If the positive rectal chlamydia results obtained in this study do reflect true infection, the current Australian approach to screening for chlamydia in women (based on a history of anal sex, anal penetration during sexual assault or anal symptoms¹¹) may miss isolated rectal infections and lead to the undertreatment of rectal and urogenital co-infection. In this study-group rectal screening based on rectal symptoms, a history of anal intercourse in the past six months, or either rectal symptoms or a history of anal sex in the past six months, would have missed 94%, 66% and 59% of positive rectal chlamydia cases, respectively. This raises the question of whether current screening recommendations should be changed.

This study was relatively small and included only women with a high probability of chlamydia infection; a larger study, or one involving a broader cross-section of women, might identify variables associated with positive rectal chlamydia results that could be used to target testing. In the absence of variables that can reliably be used to inform rectal screening in women one option would be to extend an offer of rectal chlamydia testing to all women seeking chlamydia testing, and another would be to treat all women with a positive chlamydia test as though they had rectal chlamydia.

The option of treating all women with chlamydia as if they had concurrent rectal infection then raises the question of optimal treatment. Current Australian guidelines recommend a single dose of azithromycin 1 g PO in uncomplicated urogenital infection and either doxycycline 100 mg PO BD for seven days (recommended) or azithromycin 1 g PO × 2 doses given one week apart (alternative) for rectal chlamydia.¹¹ Studies comparing the efficacy of a single dose of azithromycin 1 g PO vs doxycycline 100 mg PO twice daily for seven days for rectal chlamydia have had variable outcomes.²⁰

In order to better inform current chlamydia screening and treatment strategies, further research is needed to determine the prevalence of rectal chlamydia in women generally, to identify variables that are associated with a high probability of rectal chlamydia and can be used to target testing, if these exist, and the most effective and acceptable management for rectal chlamydia in women.

Ethics approval

Canberra Hospital and Australian National University Ethics Committees.

Footnotes

Acknowledgements

The authors thank the staff and patients of the Canberra Sexual Health Centre for their involvement in this study.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

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