Sexually Transmitted.

Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, human immunodeficiency virus (HIV), Treponema pallidum, Ureaplasma urealyticum, Mycoplasma hominis, other mycoplasmas, herpes simplex virus (HSV), and others may be acquired during sexual activity. In addition, other agents that cause genital tract disease and may be sexually transmitted include adenovirus, coxsackievirus, molluscum contagiosum virus (a member of the poxvirus group), the human papillomaviruses (HPVs) of genital warts (condylomata acuminata; types 6, 11, and others), and those associated with cervical carcinoma (predominantly types 16 and 18, but numerous others are also implicated), Klebsiella granulomatis, and ectoparasites such as scabies and lice. Some of these agents are not routinely isolated from clinical specimens. Infections with more than one agent may occur; therefore, dual or concurrent infections should always be considered.

An individual’s sexual habits and practices dictate potential sites of infection. Homosexual practices and increasingly common heterosexual practices of anal-genital or oral-genital intercourse allow for transmission of a genital tract infection to other body sites such as the pharynx or anorectic region. In addition, these practices have required that other gastrointestinal and systemic pathogens also be considered etiologic agents of STDs. The intestinal protozoa Giardia lamblia, Entamoeba histolytica, and Cryptosporidium spp. are significant causes of STDs, especially among homosexual populations. In the same group of patients, fecal pathogens, such as Salmonella, Shigella, Campylobacter, and Microsporidium, are often transmitted sexually. Oral-genital practices may provide an opportunity for N. meningitidis to colonize and infect the genital tract. Viruses shed in secretions or present in blood (cytomegalovirus [CMV]; hepatitis B, possibly C and E; other non-A, non-B hepatitis viruses; human T-cell lymphotropic virus type I [HTLV-I]; and HIV) are spread by sexual practices.

Certain infections that are sexually transmitted occur on the surface epithelium of or near the lower genital tract. The major pathogens of these types of infections include HSV, Haemophilus ducreyi, and T. pallidum.

Other Routes.

Organisms may also be introduced into the genital tract by instrumentation, presence of a foreign body, or irritation and can subsequently cause infection. These infections are often a result of infection with the same organisms capable of causing skin or wound infections. Infection can also be transmitted from mother to infant either in vivo (within the living body) or during delivery. For example, transplacental infection may occur with syphilis, HIV, CMV, or HSV. Infection in the newborn can also be acquired during delivery by direct contact with an infectious lesion or discharge in the mother and a susceptible mucous membrane such as the eye in the infant. STDs, such as HSV, C. trachomatis, and N. gonorrhoeae, may be transmitted from mother to newborn in this manner. Other organisms, such as group B streptococci, Escherichia coli, and Listeria monocytogenes originating from the mother may also be transmitted to the infant before, during, or after birth. (Infections in the fetus and newborn are discussed later in this chapter.)

Asymptomatic.

Although symptoms of genital tract infections generally cause the patient to seek medical attention, a patient with an STD, especially a female, may be free of symptoms (i.e., asymptomatic). For example, gonorrhea (Neisseria gonorrhoeae) or chlamydia (Chlamydia trachomatis) infection in the male is usually obvious because of a urethral discharge, yet females with either or both of these infections may have either minimal symptoms or no symptoms at all. Also, the primary lesion of syphilis (chancre) can be unremarkable and go unnoticed by the patient. Therefore, the lack of symptoms does not guarantee the absence of disease. Unfortunately, these asymptomatic individuals can serve as reservoirs for infection and unknowingly spread the pathogen to other individuals. Asymptomatic infections in the female caused by N. gonorrhoeae or C. trachomatis that go untreated can lead to serious sequelae such as pelvic inflammatory disease or infertility.

Dysuria.

Although a frequent presenting symptom associated with urinary tract infection, dysuria (painful urination) can commonly result from an STD caused by organisms such as N. gonorrhoeae, C. trachomatis, and HSV.

Urethral Discharge.

The presence of an inflammatory exudate at the tip of the urethral meatus is generally observed in males; the symptoms of urethral infection in females are infrequently localized. Most males complain of discomfort at the penile tip as well as dysuria. Urethritis (swelling and irritation of the urethra) may be gonococcal, caused by N. gonorrhoeae, or nongonococcal. Nongonococcal urethritis can be caused by C. trachomatis, Trichomonas vaginalis (less frequently), and genital mycoplasmas such as Mycoplasma hominis, Mycoplasma genitalium, and Ureaplasma urealyticum.

Lesions of the Skin and Mucous Membranes.

Numerous organisms can cause genital lesions that are diverse in both their appearance and their associated symptoms (Figure 74-2). The agents and their features of infection are summarized in Table 74-2. Some of these infections, such as genital herpes (caused by HSV) or genital warts (caused by HPVs and discussed in Chapter 66), are common, whereas others, such as lymphogranuloma venereum and granuloma inguinale, are uncommon in the United States. Specific HPV genotypes infect mucosal cells in the cervix and can cause a progressive spectrum of abnormalities classified as low-grade and high-grade squamous intraepithelial neoplasia (process of rapid cell growth that is faster than normal and continues to grow, i.e., a tumor) and in some cases, progress to invasive cervical cancer.

Vaginitis.

Inflammation of the vaginal mucosa, called vaginitis, is a common clinical syndrome accounting for approximately 10 million office visits each year. Women who present with vaginal symptoms often complain of an abnormal discharge and additional symptoms such as an offensive odor or itching. Vulvitis, local irritation of external genitalia, may be associated with vaginitis. The three most common causes of vaginitis in premenopausal women are vaginal candidiasis, bacterial vaginosis (group B streptococci, E. coli, and enterococci), and trichomoniasis.

Candida albicans causes about 80% to 90% of cases of vaginal candidiasis; other species of Candida account for the remaining cases. Yeast can be carried vaginally in small numbers and produce no symptoms. Most patients experiencing candidiasis complain of perivaginal itching, often with little or no discharge. Irritating symptoms such as erythema are also associated with candidiasis. Frequently, discharge is classically thick and “cheesy” in appearance.

Vaginal infection with T. vaginalis, a protozoan parasite, produces a profuse, slightly offensive, yellow-green discharge; patients frequently complain of itching. About 25% of women carrying trichomonads are asymptomatic. The World Health Organization has ranked trichomoniasis as the most prevalent, nonviral, sexually transmitted disease in the world with an estimated 172 million new cases a year.

In addition to vaginitis caused by these two organisms, there is a third type referred to as bacterial vaginosis (BV). Initially, BV was thought to be associated with Gardnerella vaginalis infection, but G. vaginalis was isolated from 40% of women without vaginitis. Bacterial vaginosis is polymicrobial in etiology, involving G. vaginalis and other facultative and anaerobic organisms. A study using three different molecular methods, including broad-range polymerase chain reaction (PCR) amplification of the 16S rDNA gene, confirms the bacterial diversity of organisms involved in this infection; 35 unique bacterial species were detected including many newly recognized species in women with BV. This study also confirmed the loss of vaginal lactobacilli and concomitant overgrowth of anaerobic and facultative bacteria. The exact mechanism for the onset of BV is unknown, although it appears to be associated with a reduction in lactobacilli and hydrogen peroxide production, a rise in the vaginal pH, and the overgrowth of BV-associated organisms. Synergistic activity of various anaerobic organisms, including Prevotella spp., Porphyromonas spp., Bacteroides spp., Peptostreptococcus spp., Mobiluncus spp. (curved, motile rods), and Mycoplasma spp., as well as G. vaginalis, seems to contribute to the pathology of BV. BV is characterized by perivaginal irritation that is considerably milder than trichomoniasis or candidiasis and is usually associated with a foul-smelling discharge often described as having a “fishy” odor. This odor is a result of products of bacterial metabolism (polyamines) being volatilized by vaginal fluids. Some patients also complain of abdominal discomfort. It appears that BV and trichomoniasis frequently coexist. Because BV can recur in the absence of sexual reexposure and other settings (e.g., nonsexually active women, virgins), BV is not exclusively sexually transmitted. BV also increases a woman’s risk of acquiring HIV, is associated with increased complications in pregnancy, and may be involved in the pathogenesis of pelvic inflammatory disease.

Although uncommon, there are other infectious causes of vaginitis. Three are briefly mentioned here because Gram stain of vaginal secretions may be helpful. First, Sobel described a number of premenopausal patients with a diffuse, exudative vaginitis with massive vaginal cell exfoliation, purulent vaginal discharge, and an occasional vaginal and cervical spotted rash. Laboratory findings included elevated pH of vaginal secretions. Also, numerous polymorphonuclear cells, an increased number of parabasal cells, the absence of gram-positive bacilli, and their replacement by occasional gram-positive cocci are observed on direct Gram stain (Figure 74-3). Basal cells appear as a result of the extensive exfoliation of epithelial cells. This clinical syndrome is referred to as desquamate inflammatory vaginitis. Symptoms associated with another disorder, lactobacillosis, resemble those of candidiasis and often follows antifungal therapy. Gram stain or wet mount typically reveals a large number of very long lactobacilli. These predominately anaerobic lactobacilli are 40 to 75 µ in length and are significantly longer than the average normal flora lactobacillus (5 to 15 µ). Finally, preexisting lesions due to other diseases may become secondarily infected with a mixed anaerobic flora of fusobacteria and spirochetes. This is referred to as fusiform-spirochete disease; this infection can progress rapidly. Gram stain examination reveals inflammatory cells in conjunction with gram-negative, fusiform bacterial morphotypes and spirochetes.

Cervicitis.

Polymorphonuclear neutrophils (PMNs) are normally present in the endocervix; however, an abnormally increased number of PMNs may be associated with cervicitis (inflammation of the cervix). Therefore, a purulent discharge from the endocervix can be observed in some cases of cervicitis. The endocervix is the site from which N. gonorrhoeae is most frequently isolated in women with gonococcal infections. In patients presenting with cervicitis, C. trachomatis can also be isolated; chlamydia have not been associated with vaginitis. Frequently, patients are infected with both pathogens. Because most women with cervicitis caused by gonococci or chlamydia are asymptomatic and cervical abnormalities are either subtle or absent in these women, an appropriate laboratory diagnosis to detect these organisms must be performed.

HSV and human papillomavirus (HPV) can also infect the cervix. In women with herpes cervicitis, the cervix is friable (bleeds easily) and may have ulcers. Affected patients may also have lower abdominal pain.

Anorectal Lesions.

As previously mentioned, because of the homosexual practice and increasingly common heterosexual practice of anal-genital intercourse, sites of infection in addition to those in the genital tract must be considered. The anorectum and pharynx are commonly infected with the classic STDs, including anal warts caused by HPV, as well as other viruses and parasites. Patients with symptoms of proctitis (inflammation of the rectum) caused by N. gonorrhoeae or C. trachomatis complain of itching, mucopurulent anal discharge, anal pain, bleeding, and tenesmus (painful straining during a bowel movement). Anorectal infection caused by HSV is associated with severe anal pain, rectal discharge, tenesmus, and systemic signs and symptoms such as fever, chills, and headaches.

In HIV-infected individuals and other immunocompromised patients, these infections tend to last longer, be more severe, and are more difficult to treat compared with infection in immunocompetent individuals. Anorectal lesions are common in HIV-infected patients and include anal condylomata, anal abscesses, and ulcers. Anal abscesses and ulcers can be due to various organisms, including CMV, Mycobacterium avium complex, HSV, Campylobacter spp., and Shigella, as well as traditional etiologic agents of STDs.