Chlamydia and Gonorrhea

Chlamydia and gonorrhea are the two most commonly reported bacterial sexually transmitted infections, caused respectively by Chlamydia trachomatis and Neisseria gonorrhoeae. Both are heavily concentrated in adolescents and young adults, frequently cause no symptoms, and can lead to serious reproductive complications if untreated. This topic describes the two infections, why they are routinely paired in screening, and the public-health concern of antimicrobial resistance in gonorrhea.

Definition

Chlamydia is infection with the obligate intracellular bacterium Chlamydia trachomatis, and gonorrhea is infection with the bacterium Neisseria gonorrhoeae; both are sexually transmitted, commonly infect the genital tract (and the rectum and pharynx), and are frequently asymptomatic.

Scope

The topic covers the two organisms and the genital, rectal, and pharyngeal infections they cause; their often-asymptomatic course in adolescents; the reproductive sequelae they can produce; and the public-health rationale for paired screening. It also notes the growing problem of antimicrobial-resistant gonorrhea. It is descriptive reference material and does not give diagnostic or treatment instructions.

Core questions

• Why are chlamydia and gonorrhea routinely tested together?
• What reproductive complications can untreated infection cause?
• Why does asymptomatic infection make these among the most under-recognized STIs?
• Why is antimicrobial resistance a particular concern for gonorrhea?

Key concepts

• Chlamydia trachomatis
• Neisseria gonorrhoeae
• Asymptomatic infection
• Pelvic inflammatory disease
• Tubal-factor infertility and ectopic pregnancy
• Extragenital (rectal and pharyngeal) infection
• Antimicrobial-resistant gonorrhea
• Nucleic acid amplification testing
• Co-infection and paired screening

Mechanisms

Both organisms infect columnar and transitional epithelium of the genital tract and can ascend from the cervix or urethra. In women, ascending infection can cause pelvic inflammatory disease, with scarring that predisposes to tubal-factor infertility and ectopic pregnancy. Many infections, particularly chlamydial cervical infection in young women, produce no symptoms, so infection persists and is transmitted silently. The two infections frequently co-occur and are detected by the same nucleic acid amplification platforms, which is why they are commonly screened as a pair. Neisseria gonorrhoeae has progressively developed resistance to successive antibiotic classes, making resistance surveillance a central public-health concern.

Clinical relevance

These infections account for much of the routinely reported STI burden and most of the screening rationale in adolescent care, so understanding them is central to interpreting screening guidelines and surveillance. This entry is educational and describes the infections and their population-level management strategy; it is not a guide to diagnosing or treating any individual.

Epidemiology

Chlamydia and gonorrhea are among the most frequently reported notifiable infections, with incidence and prevalence concentrated in adolescents and young adults, as reflected in national estimates such as those of Satterwhite and colleagues. This burden underlies recommendations for routine screening of sexually active young women, and antimicrobial-resistance trends in Neisseria gonorrhoeae are monitored as an emerging threat.

History

Gonorrhea has been recognized clinically since antiquity, while Chlamydia trachomatis was identified as a major sexually transmitted pathogen in the twentieth century. The introduction of nucleic acid amplification testing transformed detection by enabling sensitive, non-invasive screening, and the successive loss of effective antibiotics against gonorrhea has reshaped treatment guidance over recent decades.

Debates

How should antimicrobial-resistant gonorrhea be contained?

The steady erosion of effective antibiotics against Neisseria gonorrhoeae raises ongoing questions about treatment strategy, resistance surveillance, and stewardship, which national guidelines revise as resistance evolves.

Seminal works

• uspstf-2021-chlamydia
• workowski-2021
• satterwhite-2013

Frequently asked questions

Why are chlamydia and gonorrhea tested together?

They share transmission routes, frequently co-occur, and are detected by the same nucleic acid amplification tests, so combined testing is efficient and reflects their overlapping epidemiology.

What happens if these infections are left untreated?

Untreated infection can ascend in the female reproductive tract and cause pelvic inflammatory disease, which can lead to tubal-factor infertility and ectopic pregnancy; both infections can also be transmitted onward.