A review on infection with Chlamydia trachomatis

Best Practice & Research Clinical Obstetrics and Gynaecology Vol. 20, No. 6, pp. 941e951, 2006 doi:10.1016/j.bpobgyn.2006.06.003 available online at http://www.sciencedirect.com

7 A review on infection with Chlamydia trachomatis Kaveh Manavi

MD, MRCP(Ed), DipGUM, DFFP, DipHIV Department of Genitourinary Medicine, Whittall Street Clinic, Whittall Street, Birmingham B4 6DH, UK

Infection with Chlamydia trachomatis accounts for the most common bacterial sexually transmitted infection in the UK. Men between 20 and 24 years and women between 16 and 19 years have the highest prevalence of chlamydial infection. Because the majority of women with chlamydial infection are asymptomatic, a proportion remains untreated and eventually develops pelvic inflammatory disease (PID). PID can result in ectopic pregnancy, infertility and chronic pelvic pain. Screening for chlamydial infection might reduce the incidence of complications of PID. The advent of nucleic acid amplification tests and single-dose therapy for chlamydial infection has made home testing and easy treatment possible. Key words: chlamydia; diagnosis methods; nucleic acid amplification tests; screening; singledose therapy.

Questions and Literature Sources Questions  Population: women attending sexual health clinics  Interventions: tests and treatments for Chlamydia; contact tracing  Outcomes: accuracy of tests against suitable gold standards and cure rates, etc Literature sources  Electronic databases: MEDLINE, EMBASE, Cochrane Library, Best Evidence  Manual search: personal files of articles available with authors, reference lists of all known primary and traditional review articles  Contact with experts

E-mail address: [email protected] (K. Manavi). 1521-6934/$ - see front matter ª 2006 Elsevier Ltd. All rights reserved.

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INTRODUCTION Infection with Chlamydia trachomatis accounts for the most common bacterial sexually transmitted infection in the UK. Untreated cases of chlamydial infection can lead to pelvic inflammatory disease (PID), ectopic pregnancy, infertility and chronic pelvic pain in women. Untreated chlamydial infection during labour can be vertically transmitted and cause conjunctivitis and pnuemonitis in infants. Untreated chlamydial infections in men can lead to epididymo-orchitis. The economic impact of chlamydial infection on health service is enormous. In 1990, the total cost of treatment of chlamydial infection in the US was estimated to have exceeded $4 billion.1 The cost of the management of female complications of infection accounted for most of that bill. Because of the impact of chlamydial infection on the health of young people, it is important to identify and treat infected patients and their partners. Although screening programmes managed by genitourinary medicine physicians are essential, it is important that gynaecologists, urologists and general practitioners to have sufficient knowledge and training to manage chlamydial infection and its complications. THE BIOVARS AND SEROVARS OF CHLAMYDIA TRACHOMATIS Chlamydial species are Gram-negative, aerobic, obligate, intracellular pathogens. Because they are unable to synthesize their ATP, they have to use their host cell’s energy resources. For this reason chlamydiae were once considered viruses. Of the three species of chlamydia, Chlamydia trachomatis and C. pneumoniae are known human pathogens. Genetic mapping of these two chlamydial species, has, however confirmed little similarity between the two species as 70 genes in C. trachomatis do not exist in C. pneumoniae. C. trachomatis has several serovariants based on the features of their major membrane proteins. Serovars A, B and C cause trachoma. Serovars D to K infect ophthalmic, genital and rectal columnar epithelial cells leading to conjunctivitis, urethritis, cervicitis and proctitis, respectively. These serovars also infect respiratory epithelial cells and cause infant pnuemonitis. Serovars L1eL3 cause lymphogranuloma venereum (LGV), a sexually transmitted infection (STI) that occurs mostly in tropical countries. In the UK, LGV mainly occurs in men who have sex with men (MSM). THE LIFE CYCLE OF CHLAMYDIA TRACHOMATIS The chlamydial life cycle consists of two distinct phases. During the infectious phase outside its target cells, C. trachomatis forms elementary bodies that act like fungal spores and are responsible for transmission of infection. Chlamydia does not replicate in the form of elementary bodies. Inside its target cells, it forms the reticulate bodies that are capable of replication through binary fission. Reticulate bodies are not infectious. Chlamydial elementary bodies infect non-ciliated columnar cells and macrophages. Once in contact with the surface of the host cell, chlamydia induces its own endocytosis. Inside the cell, the elementary bodies germinate and form the reticulate bodies that, after an incubation of 7e21 days, begin to replicate every 3 hours. The reticulate bodies so produced then convert into elementary bodies and shed off the cell membrane through exocytosis. It is thought that chlamydia’s ability to survive phagocytosis and destruction by lysosomal enzymes is due to its unique cell-wall structure. This cell

A review of infection with Chlamydia trachomatis 943

wall is rich in cysteine and lipopolysacharide, and protects chlamydia within and out of cells. The immune response to chlamydial infection consists of polymorphonuclear and lymphocytic infiltration leading to follicle formation and fibrotic reaction. The host immune reaction does not provide long-term immunity and consequent chlamydial reinfection can occur. EPIDEMIOLOGY C. trachomatis is the cause of infections with several serious complications. Because the majority of patients infected with C. trachomatis are asymptomatic, a significant proportion of them remain undiagnosed and can develop complications of infection. C. trachomatis is transmitted through infected secretions and mucous membranes of urethra, cervix, rectum, conjunctivae and throat. In addition, an infected mother can infect her baby during vaginal delivery. As a sexually transmitted infection, C. trachomatis is the most common bacterial STI in the world, and in the UK. It has been reported that 10.3% of women and 13.3% of men <25 years of age in the UK are infected with chlamydia.2 The number of diagnosed episodes of chlamydial infection has been rising over the past 10 years (Figure 1). In 2004, women aged between 16 and 19, and men aged between 20 and 24, had the highest prevalence of chlamydial infection in the UK.3 The behavioural factors associated with chlamydial infection have been identified as involvement in unprotected sex and having multiple partners. In the UK, the risk factors of chlamydial infection in women have been reported as non-white ethnicity, aged between 16 and 19, and having had more than one sexual partner. For men, non-white ethnicity and age between 20 and 24 years have been identified as risk factors of infection.2 Identification and treatment of chlamydial infection can reduce the transmission of HIV as a significant association between chlamydial infection and HIV viral shedding has been reported.4 Men

Women 1400

Rate per 100,000 population

1400 1200 1000

<16 16-19 20-24 25-34 35-44 45+

1200 1000

800

800

600

600

400

400

200

200 0

0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004

Data sources: KC60 and STISS/ISD(D)5 returns from GUM clinics, United Kingdom

Figure 1. Rates of genital chlamydial infection by sex and age group. (With permission of the Health Protection Agency, London.)

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The role of chlamydial infection in causing PID is well documented. It has been estimated that 50% of all cases of salpingitis and infertility in the UK are caused by chlamydial infection.5 Early diagnosis and treatment of PID can reduce the prevalence of its late complications. Regular screening of young women for chlamydial infection has been reported to result in a significant reduction in the incidence of PID6 and ectopic pregnancy.7 CLINICAL MANIFESTATIONS OF CHLAMYDIA TRACHOMATIS Urogenital manifestations of uncomplicated infection Chlamydial infection in women can cause urethritis, cervicitis and salpingitis. In men it can cause urethritis and epididymo-orchitis. Chlamydial infection of the rectal mucosa can cause proctitis with rectal pain, discharge and bleeding. One of the challenges of the diagnosis of chlamydial infection is that at least 50% of infected men and 70% of infected women are asymptomatic. A significant proportion of infected patients do not, therefore, seek early medical advice. In symptomatic patients, the incubation period is between 1 and 3 weeks. In women, non-specific symptoms such as abnormal vaginal discharge, intermenstrual bleeding, dysuria or pyuria can develop. In men, dysuria or perimeatal tingling are the most common presentations. Pelvic inflammatory disease Untreated chlamydial infection leads to PID in 20e40% of infected women.8 Other micro-organisms, including Neisseriae gonorrhoeae, enteric Gram-negative rods, Streptococcus agalactiae, cytomegalovirus (CMV), Mycoplasma hominis, and Ureaplasma urealyticum, have been identified as causes of PID. PID is the result of postinfectious inflammation of female upper genital tract that includes salpingitis, endometritis and inflammation of fallopian tubes. PID will eventually lead to infertility, ectopic pregnancy9 and/or chronic pelvic pain if untreated. There are no data on how long it takes untreated chlamydial infection to develop PID. The clinical symptoms of PID are non-specific and can be easily missed in women with mild symptoms. Unfortunately, there might not be a relationship between the severity of symptoms and the severity of the disease progression. The most common symptoms of PID are lower abdominal pain, dyspareunia, abnormal vaginal discharge or bleeding. Occasionally, patients also complain of chills and fever. It is important to note that a significant proportion of women with PID never experience any symptoms and hence have subclinical PID. It has been shown that a proportion of women with tubal factor infertility and no history of acute PID have had chlamydial or gonococcal infections in the past.10 A history of new sex partner(s), unprotected sex, the use of intrauterine device (IUD), previous chlamydial or gonococcal infection or previous gynaecological operations in the presence of the above symptoms is also suggestive of an increased risk of PID. The clinical diagnosis of PID is imprecise. No single historical, physical or laboratory feature with high sensitivity and specificity for diagnosis of PID has yet been identified. Because of the possibility of subclinical PID, and the devastating impact of untreated

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PID on women’s reproductive health, it is imperative to have a low threshold for diagnosis and treatment of PID.11 The diagnosis of PID is currently based on the presence of adnexal/uterine tenderness, or cervical excitation on bimanual examination. These criteria improve the sensitivity at the cost of reduced specificity. As the result, some women without PID might be treated unnecessarily. Patients with PID can also have fever, a high number of polymorphonuclear cells (PMN) on Gram-stained microscopic examination of their vaginal material, elevated C-reactive protein and erythrocyte sedimentation rate (ESR) and increased erythrocyte aggression.12 Differential diagnoses of signs and symptoms of PID include pregnancy, ruptured ovarian cyst, appendicitis, pyelonephritis and diverticulitis. Although laparoscopy remains the gold standard diagnostic method of PID caused by salpingitis, it is unable to detect cases of endometritis and inflammation within the fallopian tubes. In addition, it is impractical to perform laparoscopy on every woman suspected of having PID. Other methods of diagnosis of PID include, endometrial biopsy and detection of plasma cell endometritis13, transvaginal ultrasound detecting thickened, fluid-filled fallopian tubes14, and MRI confirming endometrial thickening.15 Lymphogranuloma venereum A recent outbreak of LGV among MSM, including a significant number of HIV-infected patients in Western Europe, has become a cause of concern.16 Lack of standard assay for mass screening of C. trachomatis serotype L1eL3 might have led to an underestimate of the outbreak. LGV starts as single, asymptomatic genital ulcer after an incubation period of 3e30 days. If untreated, marked inflammation leads to blockage of lymphatic drainage and development of painful buboes that can form sinus tracts on drainage. LGV proctitis cam cause rectal bleeding, discharge and pain. It can be wrongly diagnosed as inflammatory bowel disease (IBD).17 Ocular manifestations of Chlamydia trachomatis Repeated conjunctival infection with C. trachomatis leads to chronic inflammation of the conjunctiva and follicle formation over its entire surface. The roughness of the conjunctival surface is pathognomonic of the infection and disrupts the flow of tears. The subsequent scarring of conjunctiva causes the eye lid to turn in and to scar the cornea; it can result in blindness if untreated. Patients with urogenital chlamydial infection can also develop inclusion conjunctivitis characterized by mucopurulent discharge and corneal scarring in chronic cases. Patients with LGV can occasionally develop conjunctivitis with lymphadenopathy. Epididymo-orchitis Inflammation of the epididymis and testes usually occurs unilaterally and is the result of ascending urogenital infections. C. trachomatis is the most common cause of epididymo-orchitis in men <35 years in the UK.18 Epididymo-orchitis presents as testicular pain and swelling with tender induration of epididymis on palpation.

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Other clinical manifestations of chlamydial infection C. trachomatis is a common cause of postgonococcal urethritis. As the incubation period of gonorrhoea is shorter than that of chlamydial infection, patients can develop dysuria after their treatment for gonorrhoea. Because concomitant gonococcal and chlamydial infections have been reported in one-third of gonococcal cases.19 Patients with gonorrhoea should be routinely treated for chlamydia. Sexually acquired reactive arthritis (SARA) is a syndrome of polyarthritis with conjunctivitis and genital chlamydial infection; it mostly affects male patients. This syndrome is associated with HLA-B27. Neonatal chlamydial infection occurs through delivery through infected birth canal. Infants infected with C. trachomatis can develop neonatal conjunctivitis after 5e12 days of birth. Some infants develop ear infections and even pneumonia characterized by wheezing and cough, but without fever.

DIAGNOSIS OF CHLAMYDIAL INFECTION AND ITS COMPLICATIONS Several different methods to diagnose chlamydial infection are available. These are generally divided into culture and non-culture methods. Culture methods for the detection of Chlamydia trachomatis Chlamydia culture is considered as the gold standard method as it has near 100% specificity.20 Because only viable infectious chlamydial elementary bodies are detected by culture, this is the method of choice for medico-legal issues. Culture methods can also be used for conduction of antibiotics susceptibility testing. The method depends on inoculation of specimens on monolayer cells susceptible to C. trachomatis. Infected cells develop intracytoplasmic inclusion bodies after 48e72 hours. The inclusion bodies contain large numbers of elementary and reticulate bodies. They are detected by direct fluorescent staining with monoclonal antibodies (DFA) against major outer membrane protein (MOMP) of C. trachomatis. The disadvantages of culture include its low sensitivity and that it depends on the laboratory inter-personnel experience. Non-culture methods for the detection of Chlamydia trachomatis The non-culture methods include enzyme immunoassay (EIA), DFA, nucleic acid hybridization techniques and nucleic acid amplification tests (NAAT). EIA uses enzyme-labelled antibodies against lipopolysaccharide (LPS) on the membrane of chlamydial elementary bodies. Because antibodies cross-react with other chlamydial species, EIAs can produce false-positive results.21 In addition, EIAs are less sensitive than the chlamydial culture method. DFA is based on direct visualization of chlamydial elementary bodies through binding of monoclonal antibodies to the MOMP molecules on their membrane. DFA is highly specific but is not suitable for large quantities of specimens because it is time consuming and labour intensive. DFA has a sensitivity of 80e90% and a specificity of 99% compared to culture.22

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Nucleic acid hybridization techniques detect chlamydial rRNA with a complementary DNA probe. The performance of this technique is not better than EIA and has a sensitivity of 85% and a specificity of 99%.20 Nucleic acid amplification tests (NAAT) The advent of nucleic acid amplification tests (NAAT) has revolutionized the diagnosis of chlamydial infection. These assays amplify and detect the nucleic sequences unique to C. trachomatis in specimens and have high sensitivity and specificity. These assays do not need viable micro-organisms and some can detect the presence of even a single nucleic sequence in the specimen. Several NAAT assays are available. They are based on different technologies and include polymerase chain reaction (PCR), strand displacement amplification (SDA), transcription-mediated amplification (TMA), nucleic acid sequence based amplification (NASBA) and molecular beacons. Their advantages in the diagnosis of chlamydial infection include their high performance (sensitivity of more than 90% and specificity of more than 99%) and their ability to produce reliable results with non-invasive specimens such as urine and self-collecting specimens such as urine23, vulvovaginal swabs24 and tampons25, making them acceptable to most patients. Because these assays are automated they can be used for screening programmes. The disadvantages of NAATs are their cost, their reduced performance in the presence of inhibitors (oestrogens, nitrates, crystals) with urine samples26 and the need to freeze urine specimens to improve the performance of the test. Pooling of specimens has reduced the cost of NAATs programmes. SCREENING FOR CHLAMYDIAL INFECTION Because the majority of patients with chlamydial infection are asymptomatic, they might not seek medical care. In view of the high prevalence of chlamydial infection, screening programmes offer a viable option for early diagnosis and management of patients. Such programmes need to be cost-effective and acceptable to patients. The assay used must therefore have a high performance. Screening of non-invasive samples alleviates the need for pelvic examination and urethral swab taking and might be more acceptable to patients. The other advantage of non-invasive sampling is that they can be collected at patients’ home and at their convenience. NAATs are automated, with high sensitivity and specificity. They have made chlamydial screening programmes of large number of patients possible.2 The detailed requirements of chlamydial screening programmes are given elsewhere.27 Use of non-invasive samples have been reported to improve the sensitivity of NAATs.23 Screening programmes have successfully used urine28 or vulvovaginal samples.29 Chlamydia screening programmes using self-collecting specimens seem to be more acceptable to patients and those screened using self-collecting specimens have been reported to have lower rate of PID than patients screened with conventional swabtaking after 1 year.30 MANAGEMENT OF UNCOMPLICATED CHLAMYDIAL INFECTION Like other STIs, the management of chlamydial infection is based on treatment of the patient and his or her infected sexual partner(s). It is therefore important to screen

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the sexual partners and treat those who are infected. The aim of this practice is to treat the infected sexual network. Apart from NAATs, the advent of single-dose therapy has been the other significant development in management of chlamydial infection. As a result, patients are now diagnosed and treated with the highest convenience and reliability. Antimicrobial groups effective against C. trachomatis include the macrolides, tetracyclines, quinolones and penicillins. Macrolides Azithromycin is the antibiotic that made single-dose therapy of chlamydial infection a reality. This macrolide is an azalide that is resistant to gastric acid, has high tissue penetrability and a long half-life. A single dose of 1 g azithromycin is sufficient to treat uncomplicated urethral, cervical or rectal chlamydial infection.11 A single dose of azithromycin and a 7-day course of doxycycline has a similar microbiological and clinical cure rate.31 It should be noted that azithromycin is not licensed for use during pregnancy and is considered a category B drug. Observational data, however, suggest that its use during pregnancy is safe.32e34 Clarithromycin, roxithromycin and josamycin, are new macrolides with a potency against C. trachomatis that is similar to azithromycin; they need to be taken for at least 7 days. Erythromycin stearate 500 mg twice daily for 10 days is the treatment of choice for chlamydial infection during pregnancy. Erythromycin base 500 mg 6-hourly for 7 days is another treatment option. Poor compliance to the course of therapy due to gastrointestinal side effects has been the main reason for treatment failure with erythromycin. For this reason, patients treated with erythromycin should have a test of cure 3 weeks after completion of treatment. Tetracyclines The tetracyclines have been a standard treatment for chlamydial infection for a long time. Their side effects and duration of treatment can lead to poor compliance. A 7-day course of doxycycline 100 mg twice a day results in a more than 90% cure rate. Tetracyclines should not be used during pregnancy. Quinolones Despite its antichlamydial activity in vitro, ciprofloxacin does not have this effect in vivo and should not be used for chlamydial treatment. Ofloxacin 400 mg twice daily for 7 days is an extremely effective anti-chlamydial treatment.35 Quinolone-resistant C. trachomatis has been identified in vitro, a development that might have an impact on their use in future. Quinolones should not be used in pregnancy. Penicillins Amoxicillin 500 mg three times a day for 7e10 days is an alternative therapy for chlamydial infection during pregnancy. Treatment should be confirmed by a test of cure 3 weeks after therapy.

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TREATMENT OF COMPLICATED CHLAMYDIAL INFECTION Complications of chlamydial infections need longer treatment. Treatment of pelvic inflammatory disease Current guidelines suggest a 2-week course of ofloxacin 400 mg twice daily and metronidazole 400 mg twice a day for treatment of PID. Alternatively, doxycycline 100 mg twice a day can substitute for ofloxacin. Ceftriaxone 250 mg/i.m. stat should be added to the above regimen in case of gonococcal PID.11,36 Patients need to be followed-up and undergo repeat bimanual examination to ensure resolution of their physical signs. Because of clinical diagnosis of PID, sexual partners of patients with PID need to be treated for chlamydial infection irrespective of their female partners’ STI screening result. Lymphogranuloma venereum Patients with LGV should be treated with doxycycline 100 mg twice a day for 3 weeks. All patients need to be followed up for clinical improvement. SUMMARY Chlamydial infection affects young, sexually active patients. Multiple partners and not using condoms have been recognized as high risk factors. The diagnosis of PID is clinical and requires a high degree of suspicion and a low threshold for diagnosis. Patients with PID should have negative screening for sexually transmitted infections. Sexual partners of such patients still need to be treated for chlamydial infection. Nucleic acid amplification tests (NAAT) have the advantage of high performance and use of non-invasive specimens for diagnosis of chlamydial infection. Single-dose therapy with azithromycin 1 g stat is the treatment of choice for chlamydial infection.

Practice points  Diagnosis of chlamydial infection is best made by using nucleic acid amplification tests.  Single-dose therapy improves drug adherence and success of chlamydial treatment.  It is important to test and treat the partners of patients with chlamydial infection as soon as possible.  A low threshold for diagnosis and treatment of pelvic inflammatory disease is recommended.

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