VOL 47: NOVEMBER • NOVEMBRE 2001❖Canadian Family Physician•Le Médecin de famille canadien 2229
clinical challenge
❖défi clinique
Just the Berries
John Hickey,MD
Diagnosing Chlamydia trachomatis
C
hlamydia trachomatis is the most prevalent bacterial pathogen causing sexually transmit- ted disease (STD) in the western world. It often goes undiagnosed and is sometimes inadequately treated when it is diagnosed. Some of the reason for underdiagnosis is that chlamydial infections often have no symptoms and only mild, non- specific signs. If left untreated, infection can per- sist for at least 15 months1 and can have potentially serious lifetime consequences. The main burden of morbidity falls on women.2Large reservoirs of the disease can be found in both asymptomatic men3and women.4 In fact, up to 25% of infected men and 50% to 70% of infected women are asymptomatic. Consequently, the chal- lenge of chlamydia control remains identification of asymptomatic individuals.
How do we identify patients who might be at risk for chlamydia infection? As with most condi- tions, we have to maintain a high index of suspi- cion. We know that certain patient populations are at higher risk5:
• patients with contacts known to have STDs,
• people with new partners in the past 2 months,
• people with more than two partners in the past 12 months,
• people using non- barrier methods of contraception,
• young people on the streets,
• intravenous drug users,
• commercial sex workers,
• people who have engaged in sex in countries where certain STDs are epidemic, and
• homosexual men.
Once a patient has been identified at high risk, the question of diagnosis arises. There are prob- lems, however, with current methods of testing.
We usually do cervical swabs but, to be accurate, endocervical epithelial cells must be included on the swab because C trachomatis is an obligate intracellular parasite. Unfortunately, many swabs include only mucus; one study estimated that 10%
to 35% of endocer vical specimens were inade- quate.6 Newer DNA amplification tests (poly- merase chain reaction and ligase chain reaction) that can be used to test urine as well as cervical swabs are becoming available. Overall sensitivities of amplified DNA tests are in the range of 90% to 95% compared with a sensitivity of only 60% to 65%
for culture.
Tips for collecting intraurethral specimens
• Warn patients that there will be some discomfort.
• Use a thin swab with a flexible wire shaft.
• Take swabs when patients have not voided for 2 hours because void- ing reduces the amount of exudate and might decrease the ability to detect organisms.
• Moisten the swab with water before insertion to reduce discomfort.
• Introduce the swab slowly (3 to 4 cm in
“Just the Berries” for Family Physicians originated at St Martha’s Regional Hospital in 1991 as a newsletter for members of the Department of Family Medicine. Its purpose was to provide useful, practical, and current informa- tion to busy family physicians. It is now distributed by the Medical Society of Nova Scotia to all family physicians in Nova Scotia. Topics discussed are suggested by family physicians and, in many cases, articles are researched and written by family physicians.
Just the Berries has been available on the Internet for several years. You can find it at www.theberries.ns.ca.Visit the site and browse the Archives and the Berries of the Week. We are always looking for articles on topics of interest to family physicians. If you are interested in contributing an arti- cle, contact us through the site. Articles should be short (350 to 1200 words), must be referenced, and must include levels of evidence and the resources searched for the data. All articles will be peer reviewed before publication.
Dr Hickey, a family physician in Antigonish, NS, has been in practice for 26 years and is editor of “Just the Berries” for Family Physicians.
2230 Canadian Family Physician•Le Médecin de famille canadien❖VOL 47: NOVEMBER • NOVEMBRE 2001
clinical challenge
❖défi clinique
men and 1 to 2 cm in women), rotate it slowly, and withdraw it gently.
• Immediately inoculate the culture medium or place the swab in the transport medium.
Tips for collecting cer vical specimens
• View the cer vix and remove any overlying mucous and vaginal secretions.
• Insert a sterile cotton tip swab 1 to 2 cm into the endocer vical canal and rotate.
• Rotate for 10 to 30 seconds and withdraw.
• Immediately inoculate the culture medium or place the swab in the transport medium.
Screening and treating
The question of generalized screen- ing remains controversial. Some studies suggest that screening all women younger than 30 is cost- ef fective in some patient popula- tions,7,8but for most regions, this is
impractical. Two groups that should be screened are pregnant women and semen donors.
This article discusses chlamydia only. For practical purposes, if you are testing for chlamydia, you should probably look for gonorrhea as well.
Treatment of C trachomatis at the early stage is simple and ef fective using 100 mg of doxycycline orally twice daily for 7 days, 500 mg of ery- thromycin four times daily for 7 days, or 1 g of azithromycin as a single wit- nessed dose (probably better for compliance). Patients and contacts should refrain from unprotected intercourse until the treatment is completed: 7 days for single-dose treatment. Failure to treat could lead to such consequences as infertility, ectopic pregnancy, and chronic pelvic pain.
Acknowledgment
I thank Dr Kevin Forward, Service Chief in the Division of Microbiolgy at the Queen Elizabeth II Health Science Centre in Halifax,
NS, and Professor in the Departments of Pathology and Microbiology and Immunology at Dalhousie University, for reviewing the draft of this article.
References
1. McCormack WM, Alpert S, McComb DE, Nichols RI, Semine DZ, Zinner SH. Fifteen-month follow-up study of women infected with Chlamydia trachomatis. N Engl J Med1979;300:123-5.
2. Thompson SE, Washington AE. Epidemiology of sexual- ly transmitted Chlamydia trachomatis infections.
Epidemiol Rev1983;5:96-123.
3. Harry TC, Saravanamuttu KM, Rashid S, Shrestha TL.
Audit evaluating the value of routine screening of Chlamydia trachomatisurethral infections in men. Int J STD AIDS1994;5:374-5.
4. Hopwood J, Mallinson H, Agnew E. Chlamydia screen- ing—should it be offered as a routine? Br J Fam Plan 1990;16:59-67.
5. Canadian Task Force on Preventive Health Care.
Canadian STD guidelines. Ottawa, Ont: Canadian Task Force on Preventive Health Care; 1998.
6. Larson J, Wulf H, Friis-Moller A. Comparison of a fluo- rescent monoclonal antibody assay and a tissue culture assay for routine detection of infections caused by Chlamydia trachomatis. Eur J Clin Microbiol 1986;5:554- 8.
7. Scholes D, Stergachis A, Heidrich FE, Andrilla H, Holmes KK, Stamm WE. Prevention of pelvic inflamma- tory disease by screening for cervical chlamydial infec- tion. N Engl J Med 1996;334:1362—6.
8. Howell MR, Quinn TC, Gaydos CA. Screening for Chlamydia trachomatisin asymptomatic women attend- ing family planning clinics. Ann Intern Med 1998;128:277-84.
