Porth's Essentials of Pathophysiology, 4e

1059

Sexually Transmitted Infections

C h a p t e r 4 1

Diagnosis andTreatment Diagnosis is based on the history of sexual exposure and symptoms. The presence of N . gonorrhea may be confirmed by identification of the organism on a gram stain or culture, but more rapid testing that can be done from a urine sample is becoming preferred. While cul- ture remains the gold standard, detection by NAATs is possible using urine and urethral swab specimens. 29 The sensitivity of these tests is similar to that of culture, and they are cost effective in high-risk populations. Updated recommendations from the U.S. Preventive Services Task Force (USPSTF) suggest that clinicians screen for gonorrhea in all sexually active men and women who are at increased risk for infection (i.e., younger than 25 years of age, new or multiple sexual partners, inconsistent condom use, sex work, men who have sex with men, or drug use). 31 Testing for other STIs, particularly syphilis and chlamydial infection, is sug- gested at the time of examination. Pregnant women are routinely screened at the time of their first prenatal visit; high-risk populations should have repeat cultures during the third trimester. Neonates are routinely treated with various antibacterial agents applied to the conjunctiva within 1 hour of birth to protect against undiagnosed gonorrhea and other diseases. Strains of N. gonorrhoeae that are resistant to penicil- lin, tetracycline, and quinolone are prevalent worldwide, and strains with other kinds of antibiotic resistance con- tinue to evolve and spread. The current treatment recom- mendation to combat penicillin- and tetracycline-resistant strains is ceftriaxone or cefixime in a single injection. 28,29 While a single injection of cefixime is still the standard treatment, some strains of N. gonorrhoeae have begun to show resistance to this dose. At this time the organ- ism is responding to higher dosing (up to 1 gm) of cefix- ime. Because gonorrhea and chlamydia frequently occur together, treatment of cefixime should be followed with azithromycin or doxycycline for chlamydia. All sex part- ners within 60 days prior to discovery of the infection should be contacted, tested, and treated. Test of cure is not required with observed single-dose therapy. Patients are instructed to refrain from intercourse until therapy is completed and symptoms are no longer present. 4 Syphilis After declining every year from 1990 to 2000, the rates of primary and secondary syphilis have been increas- ing. 32,33 The CDC estimates that 55,400 people in the United States develop syphilis each year. 32 Increased rates were primarily in men, with men who have sex with men being particularly affected. 32 There has also been an increase in congenital syphilis. 32,33 Etiology and Pathogenesis Syphilis is caused by a spirochete, Treponema pallidum. 9,10 T. pallidum is spread by direct contact with an infectious moist lesion, usually through sexual intercourse. Bacteria- laden secretions may transfer the organism during kissing

or intimate contact. Skin abrasions provide another pos- sible portal of entry. There is rapid transplacental trans- mission of the organism from the mother to the fetus after 16 weeks’ gestation, so that active infection in the mother during pregnancy can produce congenital syphilis in the fetus. Untreated syphilis can cause prematurity, stillbirth, and congenital defects and active infection in the infant (Fig. 41-8). Because the manifestations of maternal syphi- lis may be subtle, testing for syphilis is mandatory in all pregnancies. Once treated for syphilis, a pregnant woman usually is followed throughout pregnancy by repeat test- ing of serum titers. The clinical disease is divided into three stages: primary, secondary, and tertiary. Primary syphilis is character- ized by the appearance of a chancre at the site of expo- sure. 9,32–34 Chancres typically appear within 3 weeks of exposure but may incubate for 1 week to 3 months. The primary chancre begins as a single, indurated, buttonlike papule up to several centimeters in diameter that erodes to create a round or oval clean-based ulcerated lesion on an elevated base. These lesions usually are painless and located at the site of sexual contact. Primary syphilis is readily apparent in the male, where the lesion is on the scrotum or penis (Fig. 41-9). Although chancres can develop on the external genitalia in females, they are more common on the vagina or cervix, and primary syphilis therefore may go untreated. There usually is an accompa- nying regional lymphadenopathy. The infection is highly

FIGURE 41-8. Infant who presented with congenital facial syphilitic lesions. (From the Centers for Disease Control and Prevention Public Health Image Library. No. 3503. Courtesy of Dr. Joseph Caldwell.)