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HCET Home > On-line Training > RVIPP Self Study Manual: Chlamydia > Chlamydia Trachomatis Overview
1. Chlamydia Trachomatis Overview
Introduction
Chlamydia trachomatis (CT) is the most common bacterial infection of the genital tract in most developed countries and in many developing countries. An estimated 2.8 million new infections occur annually in the United States.5 Acute symptomatic infections result in substantial costs, both in terms of morbidity and dollars. However, untreated asymptomatic infections may cost even more in terms of sequelae including infertility and ectopic pregnancy. In the developing world, certain strains also cause trachoma, one of the most common, potentially preventable, causes of blindness.Etiology
CT is an obligate intracellular bacterium with a two phase life cycle. The infectious form, elementary bodies (EBs), attaches to and enters the host cell. After entering the cell, they reorganize into the metabolically active and replicative reticulate bodies (RB). Using host-derived adenosine triphosphate (ATP) as an energy source, the RBs divide by binary fission producing up to several hundred progeny in a large cytoplasmic inclusion within the cell. After replication the RBs reorganize into the infectious EBs, which are released by the host cell. The reproductive cycle takes 48 to 72 hours in tissue culture; however, the reproductive cycle probably takes longer in the body.Epidemiology
Where CT has been reported and studied in comparison with gonorrhea (GC), the incidence of CT exceeds that of GC. Conservative estimates indicate that 1 in every 20 sexually active women of childbearing age and 1 in every 10 adolescent girls are infected with CT.6 The prevalence of CT infection in men ranges from 4% to 10% in asymptomatic populations and from 15% to 20% in young men attending STD clinics.7,8 Incidence rates for CT are highest in the 15 -19 year age range and 74% of reported positives are in individuals under 25 years.9 The chlamydial infection rate increases through the teenage years and into the early twenties and then declines.8 To some extent these trends parallel rates of high risk sexual activity (i.e. unprotected sex, multiple partners, etc.), but even if this is taken into account, it still appears that the rate of infection falls with age suggesting the possibility of acquired immunity. Populations at an increased risk of infection include men and women who are sexually active under the age of 25, use condoms inconsistently, and/or have multiple partners.1 Heterosexual women and men are at higher risk than their homosexual counterparts. The risk of acquiring chlamydial infection from an infected partner has been difficult to define because infection is so often asymptomatic and data from single encounters with an infected person are sparse. However, the risk of infection has been found as high as 65% for a woman who has had multiple contacts with an infected partner.10 It is important to note that people with GC infections are frequently co-infected with CT; in some populations the reverse is true as well. Clinical presentations which identify women infected with or highly likely to be diagnosed with CT include:- pelvic inflammatory disease (PID)
- gonorrhea (GC)
- urethral syndrome (pain on urination with inflammation but no significant number of bacteria culturable from the urine)
- urethritis (gonococcal or nongonococcal)
- epididymitis
Pathogenesis
In women the initial site of infection is usually the endocervical columnar epithelial cells. Due to the presence of columnar epithelia on the ectocervix (ectopia) in adolescents and in oral contraceptive users, these women are more susceptible to infection with CT. Squamous epithelia, such are present in the vagina, are resistant, and thus adult women are less likely to develop chlamydial vaginitis. However, the transitional cell epithelia of the prepubertal female is susceptible and chlamydial vaginitis and urethritis may occur.1 Infection leads to cervicitis in most if not all women. Cervicitis may resolve spontaneously or leave a low-grade chronic infection with minimal signs of inflammation. However, infection frequently ascends to the upper genital tract to involve the endometrium and fallopian tubes producing endometritis and chronic salpingitis. The severity and the chronicity of chlamydial infections appear to be highly variable. Infection in women is typically subclinical or asymptomatic. However, if left untreated, infection may be associated with the same sequelae as clinically diagnosed salpingitis, that is, inflammation and scarring of the fallopian tubes leading to pelvic pain, fever, tubal obstruction, infertility, and high risk of having ectopic pregnancy. Acute chlamydial salpingitis is characterized by mucosal edema and inflammatory changes that may involve all layers of the tubes. When symptomatic, acute endocervical infection with CT is frequently characterized by purulent discharge, which at times may be perceived as a vaginal discharge. In men infections usually remain localized to the urethra but may spread retrograde to cause epididymitis or perhaps prostatitis. A new infection usually results in an acute inflammatory response similar to that associated with gonococcal urethritis but often with fewer white cells and less discharge. The natural course of untreated infection in men is unknown although some appear to develop a chronic low-grade urethritis. As many as 50% of sexually active men have asymptomatic or minimally symptomatic chlamydial infections, these infections may resolve spontaneously, but the duration of subclinical infection is unknown.1Complications of Infection in Females
Urethral SyndromeChlamydial infection occasionally causes urethral syndrome, which is defined as dysuria with or without pyuria in the absence of significant bacteriuria. CT can also be isolated from the urethra of women without urethral symptoms and negative endocervical cultures. It is believed that these women have endocervical infection but that it is not detected by culture.
EndometritisEndometritis is common in women with chlamydial infection. Endometritis may be symptomatic or asymptomatic. It persists despite shedding of the endometrium with menses. Symptoms usually consist of low-grade fever, abdominal pain, cramping and bleeding between menstrual periods. A histopathologic or microbiological diagnosis may be made by endometrial biopsy. However, the organism recovered may represent contamination from the endocervix. Testing of the endometrium may be more sensitive than testing of the endocervix for diagnosis of chlamydial infection; however, endometrial sampling is not a routine procedure.
Salpingitis and Acute Pelvic Inflammatory DiseaseCT may spread from the endometrium to the fallopian tubes to produce acute salpingitis or PID. Symptoms include abdominal or pelvic pain, fever, nausea, vomiting or other systemic manifestations. Physical examination reveals tenderness on movement of the cervix (the chandelier sign) and in the adnexa or uterine fundus. Occasionally, right upper quadrant pain dominates the clinical picture as a result of perihepatitis (Fitz-Hugh-Curtis syndrome) in which adhesions to the liver capsule are seen at laparoscopy. Acute symptomatic chlamydial PID is more frequent in younger women. More commonly, chlamydial PID is clinically chronic and associated with mild to moderate abdominal pain and less impressive tenderness on pelvic examination. However, such women may have significant tubal inflammation and adhesions at laparoscopy. The nature of the symptoms and the paucity of physical findings may delay diagnosis.
The chance of becoming infertile after symptomatic PID increases with the severity and number of episodes and ranges from 5.8% to 60%.11,12 However, most women who have tubal infertility have no history of salpingitis. They may have serologic evidence of a prior chlamydial infection, presumably reflecting subacute or chronic salpingitis. In some cases they appear to have persistent infection since CT is recovered from the fallopian tubes of about 15% of infertile women undergoing microtuboplasty for tubal infertility.13 The likelihood of infertility after asymptomatic untreated infection is unknown.Infection in Neonates
An infant born to a woman with chlamydial infection has about a 55% chance of being infected, but many are asymptomatic. About 20-50% of infants born to infected women develop neonatal inclusion conjunctivitis and 10-20% of infants develop pneumonia.14-16 Conjunctivitis typically presents 5 to 12 days after birth with erythematous conjunctivae and an ocular discharge that may be purulent. In infants who have received topical antibiotic prophylaxis at birth this tends to develop later. Spontaneous resolution can occur without significant sequelae; however, conjunctival scarring has been reported, and blindness can occur if not aggressively treated. Pneumonia usually presents 3-11 weeks after delivery with a cough and tachypnea with little or no fever. CT can be recovered from sputum or the nasopharnyx. If untreated the course is usually protracted with gradual resolution of symptoms over several weeks; however, it can be life-threatening. Although chlamydial infections in infants may be relatively benign, there is some evidence that pneumonia in the first 6 months of life may be associated with reactive airway disease in childhood.Infection in Males
Most men with symptomatic CT infection present with pain on urination and discharge that ranges from clear to grossly purulent. The discharge is frequently noticed when it stains underwear and typically begins seven to ten days after a new sexual contact. Physical examination usually reveals a discharge, and “milking” or “stripping” the urethra (i.e. proximal to distal massage of the ventral penis) may increase detection. Inguinal lymph nodes are typically not enlarged or tender. A Gram stain of the exudate shows nongonococcal urethritis (NGU), i.e. the presence of neutrophils and no intracellular diplococci (in the absence of concomitant gonococcal infection). In most studies CT has been associated with 30-50% of all cases of NGU.17-19 No clinical features reliably distinguish chlamydial and nonchlamydial NGU. Symptoms and incubation periods are similar (7-21 days). However, CT co-infection is found in approximately 20-40% of men infected with GC.20-22 Other sexually transmitted pathogens that may cause non-chlamydial NGU include Mycoplasma hominis, Ureaplasma urealyticum, Herpes simplex viruses (HSV), and Trichomonas vaginalis. Urethritis may also occur in association with urinary tract infections, prostatitis, urethral strictures, phimosis, Reiter’s syndrome, or after instrumentation. EpididymitisEpididymitis presents as unilateral pain and swelling of the epididymis, inguinal pain and occasionally scrotal erythema or edema. Expressible urethral discharge may be present and is particularly common in men under the age of 35. Older men with epididymitis are more likely to be infected with coliform bacteria like Escherichia coli (E. coli) or Pseudomonas aeruginosa. GC also causes epididymitis in sexually active men.
Other Manifestations in MalesProstatitis has been reported in association with chlamydial infection but it is unclear whether it is a manifestation of infection. Reiter’s syndrome is an immune-mediated systematic illness that occurs more often in men than women. It is characterized by arthritis, conjunctivitis, and urethritis which occur about one month after CT or other genital infections.
Rare Manifestations
C. trachomatis has been associated with endocarditis, pleuritis, pneumonitis, mediastinal and supraclavicular lymphadenopathy, hepatitis, fever of unknown origin and dilated cardiomyopathy.Summary
Pathophysiology
- CT is an obligate, intracellular bacterium that replicates in 48-72 hours and incubates in 1-3 weeks.
- It preferentially infects columnar or transitional epithelia, such as the urethra or endo cervix.
- Infections are often chronic, asymptomatic and reinfection is common.
Clinical Presentation
Women- 1/2 – 2/3 asymptomatic
- Cervicitis
- PID
- Perihepatitis (Fitz-Hugh-Curtis Syndrome)
- Urethritis – Usually asymptomatic
- Vertical Transmission (pneumonia, conjunctivitis) to newborn
- Urethritis
- Reiter’s Syndrome
- Prostitis
- Epididymitis
Medical Overview Quiz
- All of the following statements concerning Chlamydia trachomatis (CT) are true EXCEPT:
It is the most common bacterial infection of the genital tract in most developed countries.
Ten million cases of CT genital infection occur annually in the United States.
Sequelae of asymptomatic infections include infertility and ectopic pregnancy. - Which of the following women would be considered most at risk for CT?
A 17-year-old woman who has been with her new partner for the past two months.
A 23-year-old woman in a mutually monogamous relationship who has an IUD.
A 25-year-old single woman who uses a diaphragm for contraception. - In women, the initial site of chlamydial infection is usually?
Cervical columnar epithelia
Cervical squamous epithelia
Uterine endometrial tissue
Vaginal mucosal epithelia - Most women who have tubal infertility have had previously diagnosed salpingitis.
True
False - A woman who has had three episodes of PID is no more likely to become infertile than a
woman who has had one episode of PID.
True
False
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