Sexually Transmitted Infections



Sexually Transmitted Infections



Rosemary A. Jadack


Key Questions



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An epidemic of sexually transmitted infections (STIs) currently exists in the United States.1,2 The Centers for Disease Control and Prevention (CDC) estimate that there are 19 million new infections every year.3 More than 300,000 cases of gonococcal infections and 1.3 million chlamydial infections were reported in 2010.3 However, the true incidence of these infections is likely to be significantly higher inasmuch as many sexually transmitted infections are unreported. The cost of STIs is extremely high. It is estimated that STIs cost the health care system $17 billion every year.3 In addition, the personal costs to the individual experiencing an STI may include pain, disfigurement, psychosocial difficulties, and reproductive problems. Because of the epidemic status of these diseases and the enormous costs associated with them, it is imperative that health care providers become sufficiently knowledgeable to assess their patients’ STI status and educate them about STIs in an accurate and compassionate manner.


The term sexually transmitted infections refers to a large group of disease syndromes that can be transmitted sexually, regardless of whether the disease has manifestations in genital structures.1 In older texts, STIs are referred to as sexually transmitted diseases (STDs) and venereal diseases. Although STIs are more prevalent in the 15- to 25-year-old age group, they can occur at any age. These diseases are sometimes contracted by nonsexual transmission, as when a newborn infant contracts an STI from an infected mother during passage through the birth canal.1


A list of sexually transmitted organisms grouped according to type of pathogen is found in Box 34-1. A useful approach to learning the complex pathophysiologic processes of STIs is to group STIs according to the disease manifestations that the patient is most likely to exhibit when first seen by the health care provider. These categories of STIs and the disease manifestations associated with them are listed in Table 34-1. This chapter describes each of these categories and the pathophysiologic processes associated with each relevant STI.




Some diseases listed in Table 34-1 are discussed elsewhere in this text but have been included here for completeness. In particular, the reader may wish to refer to Chapter 33 for more detailed information on pelvic inflammatory disease and vulvovaginitis. Also, certain systemic infections are potentially transmitted by sexual contact. Cytomegalovirus infection, hepatitis A and hepatitis B, and human immunodeficiency virus (HIV) have the potential for sexual transmission. These diseases are covered in detail in Units III and IX, along with more in-depth information concerning infectious processes and immune responses. Before studying this chapter, the reader may wish to refer to Chapters 8 and 9 for a review of basic terminology such as incubation period and period of communicability. Health care providers caring for persons at risk for STIs should be aware of the potential for acquisition of systemic diseases by sexual contact and include assessment of these diseases as part of their overall clinical evaluation.


Urethritis, Cervicitis, Salpingitis, and Pelvic Inflammatory Disease


Three types of STI are manifested by urethritis (inflammation of the urethra), cervicitis (inflammation of the uterine cervix), and/or salpingitis (inflammation of the oviduct or fallopian tube). Gonorrhea is an inflammation of epithelial tissue by the organism Neisseria gonorrhoeae. In men, nongonococcal urethritis refers to urethritis resulting from a pathogen other than the gonococcus, which is usually Chlamydia trachomatis. In women, mucopurulent cervicitis refers to an inflammation of the cervix, which is usually caused by either Chlamydia trachomatis or Neisseria gonorrhoeae. Pelvic inflammatory disease, which was described in Chapter 33, is usually the result of acute salpingitis caused by gonococcal or chlamydial infection that has extended into nearby pelvic tissue.1,3,4


Gonococcal Infection


Gonorrhea is associated with the gram-negative diplococcus Neisseria gonorrhoeae.


Etiology and clinical manifestations

In gonorrhea, disease transmission occurs through contact with exudates from the mucous membranes of infected persons, usually by direct contact. The gonococcus then attaches to and penetrates columnar epithelium and produces a patchy inflammatory response in the submucosa. Although usually asymptomatic in women, gonorrhea may produce purulent vaginal discharge, dysuria, and abnormal vaginal bleeding. The most commonly affected areas in women are the cervix, the urethra, the Skene and Bartholin glands, and the anus. Among females, adolescents (ages 15 to 19 years) and young adults (ages 20 to 24 years) now have the highest rates of gonorrhea.3 In men, symptoms of urethritis, including dysuria and a purulent urethral discharge accompanied by redness and swelling at the site of infection, usually occur after a 3- to 6-day incubation period. Among males, young adults (ages 20 to 24 years) have the highest rates of gonorrhea.3 In both genders, infection and inflammation of the pharynx, conjunctivae, and anus may be present. Direct extension of the infection with gonococci occurs by way of the lymphatic system. In the female, extension may spread unilaterally or bilaterally to the oviducts, with subsequent salpingitis. In the male, direct extension of the infection most frequently occurs to the epididymis.1,3


Once gonococcal infection has spread to other areas, localized infection occurs and may cause the formation of cysts and abscesses. Purulent exudate containing the organism causes damage to tissue, and fibrous tissue replaces inflamed tissue. This hardened, fibrous tissue may result in scarring and narrowing of the urethra, epididymis, or oviducts. In women, partial or complete closure of the oviducts results in sterility. Infection of the oviducts may also result in pelvic inflammatory disease if exudate is released into the peritoneal cavity.1,5,6 As described in Chapter 33, pelvic inflammatory disease may be an acute or chronic condition causing widespread damage to the pelvic organs in the female.


Nongonococcal Infection


Etiology

Nongonococcal urethritis and cervicitis are often caused by strains of C. trachomatis that act on columnar epithelium in a manner similar to that noted for the gonococcus. The symptoms of infection with Chlamydia are generally less severe than those of gonorrhea. As with gonorrhea, the infection may spread by extension to the oviducts, and pelvic inflammatory disease may eventually result. Upper reproductive tract infection, whether symptomatic or subclinical, is an important cause of infertility and ectopic pregnancy.7 Transmission of Chlamydia during birth may result in ophthalmia neonatorum, or infection of the eyes in the newborn.1


Treatment

The resistance of N. gonorrhoeae to antimicrobial agents continues to spread and intensify. Newer antimicrobial agents such as ceftriaxone, cefixime, spectinomycin, and cephalosporin are now being used to manage uncomplicated gonococcal infections. In 2007 the Centers for Disease Control and Prevention no longer recommended fluoroquinolones for treatment of gonococcal infections because of fluoroquinolone resistance to N. gonorrheae.8,9 Increased resistance to cephalosporin is also currently being monitored.10,11 Unless chlamydial infection is ruled out, dual therapy for gonococcal and chlamydial infection consisting of azithromycin or doxycycline added to one of the aforementioned agents is recommended.8 Pelvic inflammatory disease is also generally managed with two agents to cover potential chlamydial and gonorrheal infection. A number of organizations now recommend Chlamydia (as well as gonorrhea) screening for sexually active adolescents and women through age 25 who have no symptoms in order to reduce the sequelae of infection.12



Diseases with Systemic Involvement


Several STIs cause a distinctive ulcerative lesion and disseminate throughout the body to affect multiple organ systems. Most prominent of this type of STI are syphilis, herpesvirus infections, and lymphogranuloma venereum.


Syphilis


Syphilis is a systemic infection of the vascular system consisting of five distinct stages: incubation, primary and secondary stages, latency, and late syphilis.3 Syphilis is communicable by persons with primary, secondary, or early latent syphilis.1,3 The incidence of syphilis has varied in the United States since reporting began in 1941. The rate of primary and secondary syphilis decreased during the 1990s to its lowest levels since 1941. However, overall rates increased again between 2001 and 2009, before decreasing again in 2010.4 Increased incidence rates were attributed primarily to men who have sex with men (MSM) and to men and women who engage in high-risk sexual behavior.4 An estimated 1.1 cases of primary and secondary syphilis per 100,000 population occurred in 2010.4


Etiology

Syphilis is caused by Treponema pallidum, an anaerobic spirochete. Syphilis is acquired when T. pallidum penetrates intact mucous membranes or abraded skin during sexual contact. (The process of transmission of congenital syphilis is described later.) Some of the T. pallidum pathogens remain at the original invasion site, whereas others migrate to regional lymph nodes within hours. During this incubation phase, T. pallidum is disseminated throughout the body and can invade and multiply in any organ system.1,3


Pathogenesis

During all stages of syphilis, invasion of tissue by T. pallidum results in pathologic changes in the vascular system. The inflammatory response in endothelial tissue causes the infiltration of lymphocytes and plasma cells, with subsequent endothelial swelling. The terminal arterioles and small arteries may become obliterated and no longer functional. Finally, long-term inflammation of vascular tissue results in the formation of hardened, fibrous thickening in the blood vessels and eventually tissue necrosis.1,3


After the initial incubation period of 10 to 90 days, the primary phase begins with the formation of a chancre, a painless, ulcerative lesion that arises at the original spirochete portal of entry (Figure 34-1). The chancre may remain unnoticed in a female if it occurs on the cervix or in the vagina; in fact, most cases of syphilis in women are undiagnosed until recognized by positive testing of the blood in the latent phase. In males, the chancre may form on the genitalia; in both genders, chancres may erupt on the anus, fingers, lips, tongue, nipples, tonsils, or eyelids.1,3


Sep 3, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Sexually Transmitted Infections
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