In infants, infection with C. trachomatis is the most common cause of conjunctivitis and early pneumonia. Transmission of bacteria to neonates occurs during perinatal exposure to the mother’s infected cervix. Ocular prophylaxis with silver nitrate solution or antibiotic ointments prevents gonococcal ophthalmia, but not perinatal transmission. The eye, oropharynx, urogenital tract, and rectum are initially involved and can be asymptomatic. Most neonatal infections are realized by the development of conjunctivitis 5-12 days after birth, and any infant 30 days of age or younger with conjunctivitis should be suspect. Infection with C. trachomatis is also a common cause of subacute, afebrile pneumonia, with onset occurring between 1 and 3 months of age.9

In men, complications from chlamydia are relatively uncommon. When they do occur, resulting infections include urethritis, epididymitis, and in rare cases sterility or reactive arthritis. 


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Infection with chlamydia and other STDs increases the risk of both transmitting and acquiring HIV three- to fivefold.2,13 Screening and treating patients for chlamydia would aid in the prevention of these complications.

Prevention and barriers to care

The importance of screening cannot be overemphasized. Despite national guidelines recommending routine testing for chlamydia, screening rates remain low among enrollees in both commercial and Medicaid plans.14 According to the CDC, every dollar spent on prevention, screening, and treatment could save $12 in medical complications that result from untreated disease.15

Teenagers and young adults are at the highest behavioral risk for acquiring STDs, yet routine screening rates fall short of recommendations. Unfortunately, fewer than one third of young patients actually receive information about STD prevention and testing during regular clinic visits.16 Because chlamydia is asymptomatic in an overwhelming majority of cases, clinicians who wait for their patients to report any symptoms will not only miss diagnosing the infection, they will also miss valuable opportunities for counseling about sexual-risk behaviors.  

Numerous barriers contribute to the low rate of screening, including patient-, clinician-, and system-related factors. Conducting confidential sexual histories is essential to identify patients at risk. Once identified risk is established, clinicians and other members of the health-care team can be guided to screen, treat, and counsel patients. 

The biggest barrier for young adults is concern over confidentiality. This includes fear of discussing sexual activity if a parent is present or fear of having the bill for services sent to their parents. Clinicians should be aware of the public-health laws of their state. Many states have confidentiality laws that protect minors who seek treatment for STD-related care, i.e., minors do not need parental consent, and information cannot be revealed to anyone without patient consent.

Screening guidelines for chlamydia have been developed through the cooperation of the CDC, U.S. Preventive Services Task Force, and several other clinical organizations. The groups recommend that all sexually active women younger than 26 years of age, including those who are pregnant, be screened annually for chlamydia.9

Any person with a new sexual partner or multiple partners should also be screened, regardless of gender or age. In addition, all patients who seek screening or treatment for chlamydia should also be screened for gonorrhea, syphilis and offered screening for HIV.

Test options

The number of reported cases has risen sharply since reporting began in 1984. In 1987, a total of 20 states were reporting chlamydia to the CDC; by 2000, that number had increased to all 50 states. However, the growing number of reported cases is due not only to increased screening frequency but to improved sensitivity and specificity of available tests. 

The chlamydial cell culture is considered the official gold standard. It was one of the first diagnostic screening tests. In this test, a viable organism is inoculated with the collected specimen; 48-72 hours later, intracytoplasmic inclusions develop with high numbers of elementary and reticulate bodies. These are detected by staining the major outer membrane protein. The benefits of chlamydial culture are the ability to perform medication sensitivities, high specificity, and ability to test all potential sites of exposure. However, because of increased costs and relatively low sensitivity (70%), cultures are typically reserved for legal/child abuse cases. 

In the 1980s, direct fluorescent antibody (DFA) tests and enzyme-linked immunoassays (EIAs) were developed, followed by direct DNA probe assays. Most recently, nucleic acid amplification tests (NAATs) have been introduced. One advantage common to all these testing modalities over culture is that a viable organism is no longer required.

In DFA testing, a fluorescein microscope is used to seek fluorescein-labeled antibodies that bind to the C. trachomatis elementary bodies. This test has a few advantages over culture testing. First, it has been cleared by the FDA to detect C. trachomatis in endocervical cells from women, urethral swabs from men, and urine samples from both; conjunctival and rectal specimens can also be used. The quality of endocervical cells can also be assessed with DFA testing. Finally, specimens can be stored and transported without refrigeration for up to seven days once they are fixed in the slide well. Disadvantages of DFA testing include the need for an experienced microscopist to read results, the time-consuming aspects of testing, and lower sensitivities, depending on the experience of the laboratory. 

A variety of EIA tests have been marketed for detecting C. trachomatis. These tests rely on the linking of the C. trachomatis organism to an enzyme-labeled antibody. Color change indicating the antibody’s presence is detected by a spectrophotometer. EIA tests have been approved by the FDA for screening of endocervical cells and male urethral specimens (however, they are not approved for other sites), and a single swab can be tested for both gonorrhea and chlamydia. Like DFA tests, specimens can be stored and transported without refrigeration. However, EIA testing can be expensive. 

Two direct DNA probe assays have been approved to detect C. trachomatis and Neisseria gonorrhoeae from a single specimen: Gen-Probe PACE 2 and Digene Hybrid Capture II Assays. These tests detect DNA complementary to specific ribosomal RNA sequences of C. trachomatis. Screening can be done from endocervical swabs, urethral swabs, and conjunctival specimens. Other sites have not been approved. As with other non-culture tests, direct DNA probe assays can be stored and transported without refrigeration for up to seven days. Specificity is low with this modality.