Chlamydia trachomatis infection: Clinical sciences

Chlamydia trachomatis is the most common bacterial sexually transmitted infection, and it’s a mandatory reportable infection as a public health measure. It can affect multiple anatomic sites, most commonly the urethra and cervix, but also the eyes, oropharynx, and rectum. Chlamydia is often asymptomatic, resulting in a large reservoir of untreated infections.

These infections can lead to pelvic inflammatory disease and increase the risk of infertility, ectopic pregnancy, and chronic pelvic pain. Additionally, chlamydia during pregnancy also increases the risk of prelabor rupture of membranes, preterm labor, and low birth weight infants, and transmission to the neonate may cause conjunctivitis, called ophthalmia neonatorum, and pneumonia.

Your first step in evaluating a patient who presents with a chief concern suggesting Chlamydia trachomatis infection is a focused history and physical exam. Let’s start with biologically male patients. Since chlamydia is a sexually transmitted infection, or STI, a complete sexual history is important including questions about new partners and both oral and anal intercourse.

A private, confidential discussion is important for all patients, including young patients like adolescents. Although it can be difficult, you should ask caregivers of young patients to step out of the room for this discussion. Additionally, whenever a young patient has a positive sexual activity history, always consider sexual assault or abuse, especially if the patient is a child. If there is abuse going on, you will need to follow up with allegations of abuse in accordance with your State’s law.

Once sexual history is complete, you can move on to signs and symptoms. Patients may report symptoms at various anatomic sites. They may have a sore, itchy throat or difficulty swallowing. Or they may report genitourinary symptoms such as lower abdominal pain, dysuria, pyuria, and testicular pain or swelling. Lastly, anal and rectal symptoms include painful bowel movements or rectal spotting.

Here is a high-yield fact! The majority of chlamydia infections are asymptomatic. Therefore, screening is recommended for high-risk populations, such as sexually active women under the age of 25 and men who have sex with men.

Now back to our physical exam. The findings here might also vary based on the anatomic site. So, you might find signs of conjunctivitis, such as erythema of the conjunctiva, swelling of the eyelid, or purulent ocular discharge. Next, pharyngitis presents as an erythematous throat and cervical lymphadenopathy. Then, urethritis may present with a mucoid or watery urethral discharge.

Some patients might report signs of epididymitis including unilateral swelling and tenderness of a testicle, as well as lower abdominal tenderness. Prostatitis presents with a firm, tender, and edematous prostate on digital rectal exam. Lastly, proctitis may present with swollen, tender, and erythematous rectal mucosa. If you see any of these signs in sexually active individuals, you should suspect chlamydia trachomatis infection.

And here is another high-yield fact! Even though patients most commonly present with some of these signs, in some rare cases you might see patients with genital ulcers caused by chlamydia. In fact, three strains of chlamydia, called serotypes L1, L2, and L3, can cause lymphogranuloma venereum, which is an uncommon but invasive genital ulcer disease that can lead to lymphadenopathy and proctocolitis. Keep in mind that these are different from the serotypes that cause genitourinary infections, which are types D to K, and those that infect conjunctival cells and can lead to blindness, which are serotypes A to C.

Alright, if you suspect chlamydia trachomatis infection, the next step is a nucleic acid amplification test, or NAAT, for chlamydia. Although historically culture was used for diagnosis, culture is rarely performed today. Rather, NAATs are used for screening and diagnosis. Sexual history, symptoms, and physical exam findings guide testing sites. You can swab the affected area, which can include the eye, throat, urethral meatus, or rectum. First-void urine can also be sent to diagnose urogenital infections.

Okay, let’s talk about some results. First of all, if the NAAT is negative, consider an alternative diagnosis. On the other hand, If the NAAT is positive, you have made your diagnosis of chlamydia trachomatis infection.

Treat the patient with an antibiotic, such as doxycycline. To ensure compliance, treat patients on-site or refer to an STI clinic for same-day treatment. After administering antibiotics to your patient, be sure to refer all sexual partners for evaluation and treatment as well. Counsel patients to abstain from intercourse until 7 days following completion of treatment. Additionally, they should abstain from intercourse until symptoms have resolved and all partners are treated.

Now, patients with any STI are logically at risk of other STIs. So, remember to perform additional STI testing to screen these patients for HIV, gonorrhea, and syphilis. Men who have sex with men who are HIV-negative should be offered HIV pre-exposure prophylaxis, or PrEP, to reduce the risk of acquiring HIV. Finally, retest all patients 12 weeks after treatment, because there’s a high prevalence of chlamydia among patients who have previously tested positive, largely due to reinfection.

Here is a clinical pearl. If sexual partners cannot access services for evaluation and treatment, consider expedited partner therapy, or EPT, where permitted by law. EPT allows treating sexual partners with prescriptions or medications without examining them first.

Now that we are done treating biologically male patients, let’s move on to biologically female patients. Again, start with a confidential sexual history including questions about new partners and anal, oral, or vaginal intercourse.