MEDICAL DIAGNOSTIC LABORATORIES, L.L.C. Leukorrhea Panel Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis The incubation period for C. trachomatis is 6-14 days. In Chlamydia trachomatis women, the primary site of infection is the cervix; specifically, EPIDEMIOLOGY columnar cells in the transitional zone and the endocervix. For this reason, it will not cause infections of the ectocervix Chlamydia is the most or vaginal walls. Cervical ectopy, or abnormal positioning common bacterial sexually of the cervix, can predispose one to chlamydial infection transmitted disease in the by exposing susceptible columnar epithelial cells. It is world with an estimated 90 estimated that 60% to 80% of sexually active adolescent million new cases annually females have cervical ectopy (1). This phenomenon may (1). It is the number one also account for the association between oral contraceptive reported disease in the use and chlamydia since women taking oral contraceptives United States (5). An estimated 3 million new cases occur are prone to cervical ectopy (1). each year in the U.S. alone (4). Rates of infection in the U.S. have steadily increased in the last 15 years. 1998- 2002 saw a higher incidence in the southern portion of the CLINICAL SIGNIFICANCE U.S. than in other regions (5). The highest incidence was in It is estimated that 80% of all infected individuals are adolescents and young adults, 15 to 24 years of age (4). In asymptomatic (3). Due to the lack of signs or symptoms 2004, a national study conducted from the University of North in some patients, it is believed that of all infected Carolina at Chapel Hill determined that 4.9% of young adults individuals, 25% of men and 40% of infected women in the U.S. were infected with chlamydia (15). Risk factors will go undiagnosed (6). Women who are symptomatic for infection include low socioeconomic status, young age, may experience abnormal vaginal discharge or a burning non-white race, unmarried, multiple sex partners, new sex sensation when urinating. If infection progresses into the partner, history of gonorrhea infection, and lack of barrier upper genital tract, they may experience lower abdominal contraceptive devices. pain, lower back pain, painful intercourse, nausea, fever, or bleeding between menstrual cycles. The appearance of PATHOGENESIS an infected cervix can vary greatly, from completely normal upon examination, to the presence of severe hypertrophic Chlamydia trachomatis, the cause of the sexually transmitted erosions and mucopurulent endocervical discharge. disease chlamydia, is an obligate intracellular parasite. This organism is unique, in that it is similar to both bacteria and In women, the most common manifestation of infection viruses. It is similar to bacteria because it contains RNA and is mucopurulent cervicitis. It is estimated that 20% of DNA and has a rigid cell wall. It is similar to viruses because women with mucopurulent cervicitis will harbor Chlamydia it is an obligate intracellular parasite that depends on the trachomatis (14). Lack of proper treatment of infection hosts cells for nutrients and energy. Much of the fibrosis and of the lower genital tract can progress to upper genital scarring associated with C. trachomatis infection is thought to tract infection and pelvic inflammatory disease (PID), be due, in large part, by a cell-mediated immune response. as well as other very serious complications, such as, Chlamydial heat-shock proteins (HSPS) share antigens with tubal factor infertility, ectopic pregnancy, chronic pelvic other bacterial and human HSPS. Therefore, the immune pain, lymphogranuloma venereum (LGV), endometritis, response cannot only target chlamydia, but host cells and salpingitis, and urethritis. Chlamydia infection can also tissues as well. The cytokine production associated with C. increase the risk for acquisition of HIV (2). trachomatis is one that is delayed and prolonged, as opposed to the quick short production associated with other pathogens. In pregnant women, chlamydia can have very serious Both of these characteristics, in combination with the often consequences including preterm delivery, low birth persistent infections of chlamydia, may account for many of weight, premature rupture of the membranes (PROM), the severe complications, including tubal factor infertility (1). and postpartum endometritis. There is a 60% to 70% risk of transmission of chlamydia to a neonate if it passes through the birth canal of an infected mother (1). It is antibody is used to stain the system for the evaluation estimated that 25% to 50% of exposed infants will develop of characteristic intracytoplasmic inclusions containing inclusion conjunctivitis within two weeks of birth and 10% to elementary and reticulate bodies of C. trachomatis. There 20% will develop pneumonia within 3 to 4 months of birth are certain disadvantages to this technique. Specimen (1). Chlamydia trachomatis is implicated in 20% to 60% viability is greatly affected by collection techniques and of all pneumonias during the first six months of life (14). transport conditions. Results may take anywhere from 3 to Transmission is not known to occur in-utero. Therefore, 7 days depending on growth. Although specificity is nearly neonates delivered by C-section are not at risk unless there 100%, reported sensitivity is as low as 70% to 85% (3). is premature rupture of the membranes. Therefore, culture is not a good screening test. In men, symptoms include difficulty urinating, pain or burning Point-of-care tests have recently been introduced. They can upon urination, penile discharge, testicular tenderness, and typically be performed within 30 minutes in the physician’s redness or swelling of the urethral opening at the tip of office. In some settings, such as in clinics, it may be useful the penis. Complications can include prostatitis, proctitis, to have an immediate answer if it is anticipated that the epididymitis, sterility, or narrowing (stricture) of the urethra patient may not return. These tests use antibodies that that may require surgery to correct. target lipopolysaccharides (LPS) that are found in all chlamydia species as well as other microorganisms that Some complications can occur in both men and women. could produce false-positive results (4). Point-of-care Lymphogranuloma venereum is a manifestation of tests have the lowest reported sensitivity and specificity Chlamydia trachomatis that primarily infects the lymph of any test available, 52% to 85% and 95% respectively system. Although cases do occur sporadically in the (3). These tests are generally not recommended due to U.S., it is usually associated with recent travel to endemic the lack of quality control as well as poor performance countries. Reiter’s syndrome consists of a classic triad of characteristics. urethritis, conjunctivitis, and reactive arthritis. Patients may also exhibit characteristic mucocutaneous lesions. Other Table 1. Sensitivities of Chlamydia trachomatis detection tests. sites of infection can include the throat (pharyngitis), rectum Method Sensitivity (proctatitis), and eye (conjunctivitis). Gram Stain 20% DIAGNOSIS Cell Culture 70% - 85% Laboratory diagnosis of chlamydia is crucial for definitive Point-of-Care Testing 52% - 85% diagnosis. Gram stain is not possible due to the lack of Enzyme immunoassay (EIA) 60% - 80% peptidoglycan in the cell wall. Cytological techniques consist Direct Fluorescent assay (DFA) 60% - 80% of Giemsa-stained cell scrapings that are visually inspected Pace-2 GenProbe 75% for cells with inclusion bodies. This technique is only useful in diagnosing inclusion conjunctivitis in newborns. Studies Hybrid Capture-II (HCII) Digene 75% Transcription Mediated Amplification show that only 20% of cervical infections are detected in this 89% manner (1). (TMA) GenProbe APTIMA 2 Strand Displacement Technology (SDA) 84% Serological methods have a very limited value when Becton Dickinson BDProbeTec investigating uncomplicated genital tract infection (4). Ligase Chain Reaction (LCR) 86% They are often inconclusive due to the long-lasting Abbott LCx immune response that may be present from a previous Real-Time PCR Technology 99% infection and the cross-reactivity with other bacteria including other chlamydia species. Therefore, serological Enzyme immunoassays (EIA) use immunohistochemical assays, such as the complement fixation test and the reactions to detect chlamydial antigens. However, microimmunofluorescence test are not appropriate specimen viability can be affected by collection techniques screening methods. and transport conditions. The reported sensitivity of this assay is approximately 60% to 80% (10, 11). Many of these Due to the fact that Chlamydia trachomatis is an obligate assays also target lipopolysaccharides (LPS) that are found intracellular parasite, it cannot be cultured on artificial in all chlamydia species as well as other microorganisms media. Cell culture techniques are commonly utilized. that could produce false-positive results (4). Therefore The specimen is introduced into a susceptible cell line in a specificity is low as well. They require either blocking tissue culture system. A fluorescein-conjugated monoclonal assays or confirmatory assays for all positive specimens. Direct fluorescent antibody (DFA) techniques use with chemiluminescent DNA probes are used to visualize the fluoroscein-labeled specific antibodies to detect chlamydial rRNA amplification products spectrophotometrically. Due antigens. The specimen is applied