INTRODUCTION – AGENTS

Sexually transmitted diseases are best divided into two major groups: those that cause ulcerative lesions (see Chapter 17, Ulcerative Sexually Transmitted Diseases) and those that do not. Diseases that fall into this latter group include chlamydial infections, gonococcal infections, nongonococcal urethritis, and human papilloma virus (HPV). Although new tests make diagnosis easier, results are often not available during an acute care visit, and empiric treatment with appropriate follow-up is often the best approach.

CHLAMYDIA

Epidemiology

Chlamydia trachomatis, when sexually transmitted, most commonly causes urethritis in men and cervicitis in women. The incidence of this infection is 3 to 5 million cases annually, making it the most common sexually transmitted infection in the United States.

Clinical Features

In men, C. trachomatis most commonly causes urethritis with dysuria and/or a clear urethral discharge (Table 18.1). Women, in contrast, are asymptomatic in 70–80% of cases, though rare complaints include dysuria, vaginal discharge, and spotting.

Differential Diagnosis

The differential diagnosis for Chlamydia includes:

Urethritis:

• Neisseria gonorrhoeae

• Mycoplasma genitalium

• Ureaplasma urealyticum

• adenovirus

• herpes simplex virus

• Trichomonas vaginalis

Noninfectious causes such as Reiter's syndrome and contact dermatitis from topical preparations or latex condoms should also be considered in the differential diagnosis.

Cervicitis:

C. trachomatis and N. gonorrhoeae are the most common causes of acute cervicitis. As mentioned above, noninfectious causes, including contact dermatitis from douches, scented tampons, vaginal creams, or latex condoms should also be considered.