INDIVIDUAL PATHOGENS

GONORRHEA

Microbiology

N. gonorrhoeae, the causative agent of gonorrhea, is a gram-negative, nonmotile, non-spore-forming organism that grows singly and in pairs (i.e., as diplococci).

Epidemiology

The ∼450,000 cases reported in the United States in 2016 probably represent only half the true number of cases because of underreporting, self-treatment, and nonspecific treatment without a laboratory diagnosis.

More than 70% of reported cases in the United States occur in 15- to 24-year-old women and 20- to 29-year-old men.
Gonorrhea is transmitted from males to females more efficiently than in the opposite direction, with 50–70% of women acquiring gonorrhea during a single unprotected sexual encounter with an infected man. Roughly two-thirds of all infected men are asymptomatic.
Drug-resistant strains are widespread. Penicillin, ampicillin, and tetracycline are no longer reliable therapeutic agents, and oral cephalosporins and fluoroquinolones are no longer routinely recommended. In addition, strains highly resistant to ceftriaxone and azithromycin have been isolated in several countries, and combined resistance may contribute to the failure of the currently recommended dual therapy (see below).

Clinical Manifestations

Except in disseminated disease, the sites of infection typically reflect areas involved in sexual contact.

Urethritis and cervicitis have an incubation period of 2–7 days and ∼10 days, respectively. See above for details.
Anorectal gonorrhea can cause acute proctitis in women (due to the spread of cervical exudate to the rectum) and MSM.
Pharyngeal gonorrhea is usually mild or asymptomatic and results from oral–genital sexual exposure (typically fellatio). Pharyngeal infection almost always coexists with genital infection, resolves spontaneously, and is rarely transmitted to sexual contacts.
Ocular gonorrhea is typically caused by autoinoculation and presents as a markedly swollen eyelid, hyperemia, chemosis, and profuse purulent discharge.
Gonorrhea in pregnancy can have serious consequences for both the mother and the infant.
- Salpingitis and PID are associated with fetal loss.
- Third-trimester disease can cause prolonged rupture of membranes, premature delivery, chorioamnionitis, funisitis, and neonatal sepsis.
- Ophthalmia neonatorum, the most common form of gonorrhea among neonates, is preventable by prophylactic ophthalmic ointments (e.g., containing erythromycin or tetracycline), but treatment requires systemic antibiotics.
Gonococcal arthritis results from dissemination of organisms due to gonococcal bacteremia. Pts present during a bacteremic phase (relatively uncommon) or with suppurative arthritis involving one or two joints (most commonly the knees, wrists, ankles, and elbows), with tenosynovitis and skin lesions. Menstruation and complement deficiencies of the membrane attack complex (C5–C9) are risk factors for disseminated disease.

Diagnosis

NAATs, culture, and microscopic examination (for intracellular diplococci) of urogenital samples are used to diagnose gonorrhea; NAAT of urine samples is most sensitive. A single culture of endocervical discharge has a sensitivity of 80–90%.

Treatment: Gonorrhea

See Table 86-2.

TABLE 86-2: Recommended Treatment for Gonococcal Infections: Adapted from the 2015 Guidelines of the Centers for Disease Control and Prevention
DIAGNOSIS	TREATMENT OF CHOICE^a
Uncomplicated gonococcal infection of the cervix, urethra, pharynx^b, or rectum
First-line regimen	Ceftriaxone (250 mg IM, single dose) *plus* Azithromycin (1 g PO, single dose)
Alternative regimens^c	Cefixime (400 mg PO, single dose) or ceftizoxime (500 mg IM, single dose) or cefotaxime (500 mg IM, single dose) or spectinomycin (2 g IM, single dose)^d,eor cefotetan (1 g IM, single dose) plus probenecid (1 g PO, single dose)^dor cefoxitin (2 g IM, single dose) plus probenecid (1 g PO, single dose)^d *plus* Azithromycin (1 g PO, single dose)
Epididymitis	Ceftriaxone (250 mg IM once) followed by doxycycline (100 mg PO bid for 10 days)
Pelvic inflammatory disease	See text on specific syndrome
Gonococcal conjunctivitis in an adult	Ceftriaxone (1 g IM, single dose)^f
Ophthalmia neonatorum^g	Ceftriaxone (25–50 mg/kg IV, single dose, not to exceed 125 mg)
Disseminated gonococcal infection^h
Initial therapyⁱ
Pt tolerant of β-lactam drugs	Ceftriaxone (1 g IM or IV q24h; recommended) or cefotaxime (1 g IV q8h) or ceftizoxime (1 g IV q8h)
Pts allergic to β-lactam drugs	Spectinomycin (2 g IM q12h)^d
Continuation therapyⁱ	Cefixime (400 mg PO bid)
Meningitis or endocarditis	See text for specific recommendations^j

^aTrue failure of treatment with a recommended regimen is rare and should prompt an evaluation for reinfection, infection with a drug-resistant strain, or an alternative diagnosis.

^bCeftriaxone and azithromycin are the only agents recommended for treatment of pharyngeal infection.

^cSee text for follow-up of persons with infection who are treated with alternative regimens.

^dSpectinomycin, cefotetan, and cefoxitin, which are alternative agents, currently are unavailable or in short supply in the United States.

^eSpectinomycin may be ineffective for the treatment of pharyngeal gonorrhea.

^fPlus lavage of the infected eye with saline solution (once).

^gProphylactic regimens are discussed in the text.

^hHospitalization is indicated if the diagnosis is uncertain, if the pt has frank arthritis with an effusion, or if the pt cannot be relied on to adhere to treatment.

ⁱAll initial regimens should also include azithromycin (1 g PO, single dose) and should be continued for 24–48 h after clinical improvement begins, at which time the switch may be made to an oral agent (e.g., cefixime) if antimicrobial susceptibility can be documented by culture of the causative organism. If no organism is isolated and the diagnosis is secure, then treatment with ceftriaxone should be continued for at least 1 week.

^jHospitalization is indicated to exclude suspected meningitis or endocarditis.

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