New evidence suggests that a seven-day course of doxycycline may be more appropriate as a first-line treatment for chlamydia infection than a stat dose of azithromycin. Although a seven-day treatment is less suitable for patients, increased use of doxycycline may help reduce the high rates of transmission and re-infection with chlamydia. Pharyngeal swabs should be considered for chlamydia and gonorrhea testing due to the increase in pharyngeal gonorrhea infection rates, especially in abnormal sexual intercourse such as having sex with men.
The highest Chlamydia trachomatis infection rates have been reported in young people; Between 2013 and 2017, 82% of the cases reported to the Environmental Science and Research Institute (ESR) were in persons aged 15-29. For example, data show that one in three women and one in five men in New Zealand by the age of 38 have at least one chlamydia infection.
Re-Infection is Common
Reinfection rates are high for chlamydia. For example, data collected from laboratory testing services covering the Wellington region between 2012 and 2015 found that 18% of people who tested positive for chlamydia or gonorrhea infection tested positive again in the next six weeks to six months. And untreated rectal chlamydia can be an important source of reinfection in kins.
Men who have sex with men (MSM) have typically been the center of attention to investigate rectal chlamydia infection. However, data from studies over the past decade suggest that rectal chlamydia in women can be an overlooked source of reinfection.
Most patients with genital chlamydia also have a rectal infection. A meta-analysis of 14 studies conducted in the UK, USA, Canada, Australia and Europe found that an average of 68% of women with genital chlamydia infection were also positive for rectal infection. Conversely, rectal infection is rare in the absence of genital infection; About 2% of the women in these studies tested positive for rectal infection, but not for genital infection.
Most people with rectal chlamydia infections are asymptomatic: At least 90% of women and 70% of MSM with rectal chlamydia infection are asymptomatic. Rectal infection in women is not related to sexual practices: Research has not found an association between rectal chlamydia infection and whether or not women have anal intercourse. This suggests that rectal infection occurs in many women, not from sexual practices, but due to the spread of the genital infection to the rectal tissue.
Is Doxycycline Effective in the Treatment of Rectal Chlamydia?
A single dose of stat azithromycin is currently the recommended first-line antibiotic regimen for the treatment of genital chlamydia infection and is effective in 94% of patients. An alternative treatment is a seven-day course of doxycycline that is effective in 97% of patients with genital chlamydia infection. Because both regimens offer similar efficacy and azithromycin is usually a one-time dose given in the clinic at the time of appointment, it has often been used as a treatment for patients with genital chlamydia infection and as a first-line treatment for sexual contacts.
However, azithromycin is less effective than doxycycline in treating rectal chlamydia infection. One meta-analysis reported that the average efficacy of a stat dose of azithromycin for the treatment of rectal chlamydia was 83% compared to> 99% for a seven-day course of doxycycline.
Azithromycin Use May Cause Resistance to Other STIs
Mycoplasma genitalium is an emerging cause of STIs such as persistent urethritis in men and cervicitis and pelvic inflammatory disease in women. 1 Data suggest that the use of single dose azithromycin regimens may result in the emergence of resistance in M. genitalium. Therefore, reducing the use of azithromycin as first-line therapy for chlamydia infection may help prevent resistance in M.genitalium, as this organism shares similar infection sites with chlamydia.
Routine Treatment of Chlamydia Infection in Women
The emerging evidence that asymptomatic rectal chlamydia infection is common in women and azithromycin responds less to the stat dose than genital infection suggests that this may be a major cause of recurrent or persistent chlamydia infection.
The first step is to consider prescribing 100 mg of doxycycline twice daily for seven days. This regimen is estimated to be effective in approximately 97% of patients with genital or rectal chlamydia. Although azithromycin is less effective, it still results in clearance for most patients and may be a viable option if there is concern that the seven-day course of doxycycline will not be complete.
New evidence poses a dilemma for testing in women: Anorectal swabs are currently recommended for women who report having anal intercourse. Additionally, current guidelines recommend retesting for treatment in rectal chlamydia patients. However, the data indicate that reported sexual practices are not a useful guide for deciding whether rectal swabbing is necessary.
Collection of rectal swabs for all female patients will increase the invasiveness of the test and result in a large number of additional tests. In addition, if all women who test positive for rectal infection are asked to return for a treatment test, this will place an additional burden on patients due to the length and cost of re-hospitalization. A pragmatic approach would be:
• Genital swabs should be collected
• It should be assumed that women who test positive for genital chlamydia may also have rectal infection.
• 100 mg of doxycycline should be prescribed twice a day for seven days.
Healing testing using both genital and anorectal swabs can then be reserved for patients with risk of re-infection or the consequences of re-infection, such as not treating sexual contacts if insertion of an intrauterine device is planned. or there are concerns about adherence to a seven-day regimen.
A vulvovaginal NAAT swab (usually tested for both chlamydia and gonorrhea), plus a clinician-collected high vaginal culture swab if symptomatic, and an endocervical swab for gonorrhea culture (if available). To reduce re-infection, monitor and treat sexual contacts: Sexual contact should be maintained from the previous three months, treated empirically, preferably with a seven-day course of doxycycline, and testing for STIs should be recommended.
Routine Treatment of Chlamydia Infection in Men
Test recommendations for men who have sex with men do not change. Routine testing for rectal and pharyngeal chlamydia and gonorrhea infection as part of sexual health check remains appropriate in this high-risk population. Rectal chlamydia infection is more common in MSM than urethral infection, is usually asymptomatic and can increase the risk of HIV transmission. In addition to rectal swabs, it is recommended that swabs be collected to routinely test for pharyngeal chlamydia or gonorrhea infection on MSM. A recovery test is recommended for patients with positive rectal or pharyngeal test results. Doxycycline is also the recommended treatment for rectal chlamydia in men.
For heterosexual men with urethral chlamydia, it is probably preferable to prescribe a seven-day course of doxycycline, as the use of azithromycin may contribute to the development of resistance in M.genitalium, a cause of urethritis. Unlike heterosexual women, there are currently no data to suggest that heterosexual men with genital chlamydia have high rectal infection rates.
Increasing Rates of Gonorrhea, Including Pharyngeal Infection Rates
In New Zealand for the current example, the National gonorrhea infection rate is about 100 cases per 100,000 population, with higher rates for men than women. The incidence has increased in recent years, with a greater proportion of positive gonorrhea tests from pharyngeal swabs in men. One of the main reasons for increased gonorrhea rates, especially in large urban areas, is the higher likelihood of transmission among MSMs.
Pharyngeal infection is typically asymptomatic and is thought to play an important role in the development of antibiotic resistance in N. gonorrhea. This is because antibiotic therapy leads to the development of resistance in oral bacteria and can then pass the resistance genes to N. gonorrhoea in the pharynx.
Genital gonorrhea infection in men is usually symptomatic. Testing for asymptomatic infections in heterosexual men is not necessary, but should be recommended at least once a year as part of a routine sexual health checkup at MSM due to the high rates of gonorrhea in this population. Collected specimens should include rectal and pharyngeal NAAT swabs and the first blank urine specimen to test for chlamydia and gonorrhea infection. Taking pharyngeal swabs in heterosexual men may be appropriate if there is a high degree of suspicion, for example if they have had chlamydia or gonorrhea infection from sexual contact.
In women, testing for genital gonorrhea infection is recommended during sexual checkup, as up to 80% of women with genital gonorrhea infection are asymptomatic. If there is a high degree of suspicion, for example chlamydia or gonorrhea infection from sexual contact, it may be appropriate to take pharyngeal swabs.
The recommended primary treatment for gonorrhea infection is the same for genital, rectal or pharyngeal infections: ceftriaxone, 500 mg intramuscular injection and azithromycin, 1 g stat. The recommended first-line treatment for pharyngeal chlamydia infection is the same as for rectal chlamydia: doxycycline is 100 mg twice daily for seven days.
Author: Ozlem Guvenc Agaoglu