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.

Bartholinitis.

In adult women, the Bartholin’s gland is a 1-cm mucus-producing gland on each side of the vaginal orifice. Each gland has a 2-cm duct that opens on the inner surface of the labia minora. If infected, this duct can become blocked and result in a Bartholin’s gland abscess. Although N. gonorrhoeae and C. trachomatis can cause infection, anaerobic and polymicrobic infections originating from normal genital flora are more common.

Females.

Infection of the female reproductive organs (i.e., uterus, fallopian tubes, ovaries, and even the abdominal cavity) can occur. The organisms spread as they ascend from lower-tract sites of infection. Organisms may also be introduced to the reproductive organs by surgery, instrumentation, or during childbirth.

Males.

Infections in male reproductive organs can also occur and include epididymitis, prostatitis, and orchitis (testicular swelling). Epididymitis, an inflammation of the epididymis, is commonly seen in sexually active men. Patients complain of fever and pain and swelling of the testicle. N. gonorrhoeae and C. trachomatis are common causes of epididymitis. However, enterics and coagulase-negative staphylococci can also cause infection in men older than 35 years of age and in homosexual men; these infections are often associated with obstruction by the prostate gland.

Prostatitis is a term to clinically describe adult male patients who have perineal, lower back, or lower abdominal pain, urinary discomfort, or ejaculatory complaints. Prostatitis is caused by both infectious and noninfectious means. Bacteria can cause an acute or chronic prostatitis. Patients with acute bacterial prostatitis have dysuria and urinary frequency, symptoms typically associated with lower urinary tract infection. Frequently, these patients have systemic signs of illness such as fever. Chronic bacterial prostatitis is an important cause of persistent bacteriuria in the male that leads to recurrent bacterial urinary tract infections. The common causes of these infections are similar to the bacterial causes of lower urinary tract infections such as Escherichia coli and other enterics.

Finally, inflammation of the testicles, orchitis, is uncommon and generally acquired by the blood-borne dissemination of viruses. Mumps is associated with most cases. Patients exhibit testicular pain and swelling following infection. Infections range from mild to severe.

Urethral.

Urethral discharge may occur in both males and females infected with pathogens such as Neisseria gonorrhoeae and Trichomonas vaginalis. The presence of infection is more likely to be asymptomatic in females because the discharge is usually less profuse and may be masked by normal vaginal secretions. Ureaplasma urealyticum can also be isolated from male urethral discharge.

A urogenital swab designed expressly for collection of such specimens should be used. These swabs are made of cotton or rayon treated with charcoal to adsorb material toxic to gonococci and wrapped tightly over one end of a thin wire shaft. Cotton- or rayon-tipped swabs on a thin wire may also be used to collect specimens for isolation of mycoplasmas and chlamydiae. Calcium alginate swabs are generally more toxic for HSV, gonococci, chlamydiae, and mycoplasmas than are treated cotton swabs. Because Dacron swabs are least toxic, they are recommended for viral specimens. Dacron-tipped swabs on plastic shafts are also acceptable for chlamydiae and genital mycoplasmas.

To obtain a urethral specimen, a swab is inserted approximately 2 cm into the urethra and rotated gently before withdrawing. Because chlamydiae are intracellular pathogens, it is important to remove epithelial cells (with the swab) from the urethral mucosa. Separate swabs for cultivation of gonococci, chlamydiae, and ureaplasma are required. When profuse urethral discharge is present, particularly in males, the discharge may be collected externally without inserting a sampling device into the urethra. However, a urethral swab for chlamydiae must be collected on males. A few drops of first-voided urine have also been used successfully to detect gonococci in males.

Because T. vaginalis may be present in urethral discharge, material for culture should be collected by swab as described and another specimen collected on a swab and placed into a tube containing 0.5 mL of sterile physiologic saline. This specimen should be delivered to the laboratory immediately. Direct wet mounts and cultures for T. vaginalis can be performed from this second specimen. Commercial media for culture of Trichomonas are available. The first few drops of voided urine is a suitable specimen for recovery of Trichomonas from infected males, if it is inoculated into culture media immediately. Alternatively, material may be smeared onto a slide for a fluorescent antibody stain. Plastic envelopes for direct examination and subsequent culture are also available (InPouch TV, BIOMED, White City, Oregon); sensitivity of this system is superior to other available methods, and organism viability is maintained up to 48 hours (Figure 74-4). In addition, several other techniques are available, including enzyme immunoassay, latex agglutination tests, and the Affirm VPIII probe (Becton Dickinson, Cockeysville, Maryland); polymerase chain reaction (PCR) has also been used to detect T. vaginalis directly in clinical specimens.

N. gonorrhoeae may be detected from clinical specimens using nucleic acid-based methods, including PACE 2 and APTIMA GC (Hologic/GenProbe, San Diego, CA) using a DNA probe that hybridizes to organismal rRNA. Additional nucleic acid-based tests include Roche AMPLICOR (Roche Diagnostics, Indianapolis, IN) and the BD ProbeTecET (BD Diagnostics, Sparks, MD). Fully automated systems for complete sample processing are now available that reduce technical time, such as the BD Viper System (BD Diagnostics, Sparks, MD) and the PANTHER System (Hologic/GenProbe, San Diego, CA). These tests are widely used for quick detection of N. gonorrhoeae from vaginal, urethral, thin-prep, and urine specimens.

Cervical/Vaginal.

Organisms that cause purulent vaginal discharge (vaginitis) include T. vaginalis, gonococci, and, rarely, beta-hemolytic streptococci. The same organisms that cause purulent infections in the urethra may also infect the epithelial cells in the cervical opening (os), as can HSV. Mucus is removed by gently rubbing the area with a cotton ball. The urethral swab is inserted into the cervical canal and rotated and moved from side to side for 30 seconds before removal.

Swabs are handled as previously described for urethral swabs for isolation of Trichomonas and gonococci. Chlamydiae cause a mucopurulent cervicitis with discharge. Endocervical specimens are obtained after the cervix has been exposed with a speculum, which allows visualization of vaginal and cervical architecture, and after ectocervical mucus has been adequately removed. The speculum is moistened with warm water, because many lubricants contain antibacterial agents. Because normal vaginal secretions contain great quantities of bacteria, care must be taken to avoid or minimize contaminating swabs for culture by contact with these secretions. A small, nylon-bristled cytology brush, or Cytobrush, may be used to ensure that cellular material is collected. Collection may result in patient discomfort and bleeding.

In addition to cervical specimens, which are particularly useful for isolating herpes, gonococci, mycoplasmas, and chlamydiae, vaginal discharge specimens may be collected. Organisms likely to cause vaginal discharge include Trichomonas, yeast, and the agents of BV. Swabs for diagnosis of BV are dipped into the fluid that collects in the posterior fornix of the vagina.

Genital tract infections caused by sexually transmitted agents in children (preadolescents) are most often the result of sexual abuse. Because of medico-legal implications, the laboratory should treat specimens from such patients with extreme care, carefully identifying and documenting all isolates. Although nucleic acid-based testing methods are available for the identification of organisms associated with sexual abuse cases, culture remains the preferred method of detection for C. trachomatis and N. gonorrhoeae. In addition, cultivation of the isolate may be required to link the specific isolate to the perpetrator using epidemiologic studies.

Because it is impossible to exclude contamination with vaginal flora, obtaining swabs of Bartholin gland exudate is not recommended. Infected Bartholin glands should be aspirated with needle and syringe after careful skin preparation, and cultures should be evaluated for anaerobes and aerobes.

Transport.

Swabs collected for isolation of gonococci may be transported to the laboratory in modified Stuart’s or Amies’ charcoal transport media and held at room temperature until inoculated to culture media. Good recovery of gonococci is possible if swabs are cultured within 12 hours of collection. Material that must be held longer than 12 hours should be inoculated directly to one of the commercial systems designed for recovery of gonococci, described later in this chapter.

Swabs for isolation of chlamydiae and mycoplasmas are transported in specific transport media containing antibiotics and other essential components. Specimens for chlamydia culture should be transported on ice. (Specimens transported at room temperature should be inoculated within 15 minutes of collection.) Specimens can be stored at 4° C for up to 24 hours. If culture inoculation will be delayed more than 24 hours, specimens should be quick-frozen in a dry ice and 95% ethanol bath and stored at −70° C until cultured. If collected and transported in specific transport media, specimens for genital mycoplasma culture may be transported on ice or at room temperature. If not in genital mycoplasma transport media, specimens should be transported on ice to suppress the growth of contaminating flora.

Miscellaneous Infections

Infections of the male prostate, epididymis, and testes are usually bacterial. In younger men, chlamydia predominates as the cause of epididymitis and possibly of prostatitis. Urine or discharge collected via the urethra is the specimen of choice unless an abscess is drained surgically or by needle and syringe. The first few milliliters of voided urine may be collected before and after prostatic massage to try to pinpoint the anatomic site of the infection. Cultures are inoculated to support the growth of anaerobic, facultative, and aerobic bacteria, as well as gonococci.

Infections of Neonates and Human Products of Conception

Suspected infections acquired by the fetus as a result of a maternal infection that crosses the placenta (congenital infection) can be diagnosed culturally or serologically in the newborn. Because maternal IgG crosses the placenta, serologic tests are often difficult to interpret (see Chapter 10). For culturable agents, the most definitive diagnoses involve recovery of the pathogen in culture. HSV, varicella-zoster virus (VZV), enteroviruses, and cytomegalovirus (CMV) can be cultured easily, as can most bacterial agents. Rubella and parvovirus B19 are more difficult to culture. Nasal and urine specimens offer the greatest yield for viral isolation, although blood, cerebrospinal fluid, and material from a lesion can also be productive. Systemic neonatal herpes without lesions may be difficult to diagnose unless tissue biopsy material is examined, because the viruses may not be present in cerebrospinal fluid or blood. Bacteria and fungi can be isolated from lesions, blood, and other normally sterile sites.

Determining the presence of fetal immunoglobulin M (IgM) directed against the agent in question establishes the serologic diagnosis of congenital infection. Until recently, ultracentrifugation was required for separation of IgM from IgG, the only definitive means of preventing false-positive results caused by maternal IgG or fetal rheumatoid factor. Ion-exchange chromatography columns, antihuman IgG, and bacterial proteins that bind to IgG are commercially available for removing cross-reactive IgG and rheumatoid factor to obtain more homogeneous IgM for differentiation of fetal antibody. Indirect fluorescent antibody and enzyme-linked immunosorbent assay (ELISA) test systems are commercially available to detect IgM against T. gondii, rubella, CMV, HSV, and VZV. Interference by rheumatoid factor is still a consideration in most commercial IgM test systems (see Chapter 9). Our ability to detect viral inclusions in tissue, conjunctiva scrapings, and vesicular lesions, traditionally performed with Giemsa stain, has been improved as a result of monoclonal and polyclonal fluorescent antibody reagents, which are described in the chapters that discuss individual agents.

Infections that infants can acquire as they pass through an infected birth canal or are related to difficult labor, premature birth, premature rupture of the membranes, or other events include the following:

In the laboratory, these infections are diagnosed by direct detection or culturing for the agents when possible, or by performing serologic tests. The appropriate specimens (e.g., cerebrospinal fluid, serum, pus, tracheal aspirate) should be examined and inoculated immediately. Routine body surface cultures of infants in intensive care have not been shown to be helpful for predicting subsequent disease.

Finally, certain infectious agents are known to cause fetal infection and even abortion. For example, Listeria monocytogenes, although usually the causative agent of mild flulike symptoms in the mother, can cause extensive disease and abortion of the fetus if infection occurs late in the pregnancy. Therefore, isolation of the organism from the placenta and from tissues of the fetus is important.