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Every year a small devilish bacteria, Chlamydia trachomatis, attacks nearly 3 million Americans.  It especially targets young, sexually active women.  Unfortunately the overwhelming majority of people harboring this organism experience no symptoms warning that something is amiss.  Only months, years or even decades later chronic pelvic pain, discomfort during sexual intercourse or infertility appear as sequelae to a long forgotten liaison.  Understanding Chlamydia its symptoms and complications focuses attention toward early diagnosis, treatment and avoidance of complications.


Generally considered a sexually transmitted infection or STI, nearly 140 million cases of Chlamydia will occur this year throughout the world compared to nearly 80 million cases of gonorrhea.  While impressive, these figures pale in comparison to the 140 million trichomonas, 400 million genital herpes and 300 million HPV infections anticipated within the next 12 months.  Estimates suggest 1 million STIs will occur today.

Chlamydia only infect humans and seem to enjoy a special attraction to young women between ages 15-25.  Among sexually active women in this age group, as many as 1 in 10 will be eventually infected at least once.  A considerably higher prevalence exists among African Americans than whites by a ratio as great as 6-10 to 1.

Unfortunately a prior infection fails to confer any immunity against subsequent re-infection.  As many as 1 in 5 women be re-infected within the 12 months following an initial infection.


A high rate of transmission almost guarantees infection during relations with an infected individual.  A solitary sexual episode passes the bacteria to its new host in as many as 25-70% of contacts.  Chlamydia readily pass from men to women and in the opposite direction.  Gays, both male and female, experience high rates of infection.

The bacteria spread through vaginal and anal sex more readily than during oral sex.  During oral sex infection passes more easily from male to female.  With homosexual activities, oral infection strikes the receptive partner rather than the insertive individual.  Ejaculation is not necessary for transmission.

While toilet seats and shaking hands pose no threat, contaminated sex toys readily spread the infection.

Chlamydia require moist mucous membranes for transmission.  In young girls and adolescents, especially susceptible columnar cells line a portion of the external cervix.  With maturation, typically in women in their mid-20s, these cells retract into the cervical canal and become somewhat less easily infected by the Chlamydia.  Vaginal tissues appear only slightly less hospitable.

Other tissues that seem to entice Chlamydia include the urethra, fallopian tubes, anus, rectum, throat and inner eyelids.

More than 75% of women infected with the bacteria fail to experience any symptoms; among men 50% remain asymptomatic.  Although the body ultimately casts off the bacteria, they may linger for months to years hidden in the tissues, silent, multiplying and capable of passing to a new liaison.


Incubation requires 1-3 weeks.  In 20-25% of women, symptoms characteristically relate to cervical involvement.  Manifestations include a white, cloudy or watery cervical/vaginal discharge which alternatively may be thick and milky.  Discomfort during sex medically referred to as dyspareunia may occur.  Bleeding or simply spotting after intercourse often results from irritation of the friable, delicate tissues of the cervix.

A number of processes allow the bacteria to ascend through the cervix to attack the wall of the uterus where endometritis may develop.  This rarely causes significant concern as the lining of this organ sheds periodically during menstruation.

Of more concern, the next site involves the relatively fragile Fallopian tubes which serve as a channel between the ovary and uterus.  Infection and its accompanying inflammation lead to abdominal, pelvic and low back pain together with low grade fever.

As the inflammation resolves and the tissues heal, deposits of connective or scar tissue tend to form.  Not infrequently this results in occlusion or blockage of the Fallopian tube which dramatically increases the risk for infertility or tubal pregnancy.

Infection of the urethra causes urethritis which results in symptoms reminiscent of a urinary tract infection: burning, frequency and urgency.  Rectal involvement is often acquired either through anal intercourse.  In women another avenue of infection occurs with contamination of the area during cleansing after a bowel movement from front to back.  Proctitis manifests as localized pain, rectal discharge or possibly blood on the stool or toilet tissue.

Even the conjunctiva may be involved generally as a result of hand-eye contact during sexual activities.  Although mostly asymptomatic, some women develop oral infection manifest as sore thrnaatoat or redness of the tonsillar area.  Inflammation of the lungs or pneumonitis is another complication.

Rarely the bacteria ascend through the Fallopian tubes and attack the capsule lining the liver.  Right upper abdominal pain that increases with deep breathing, coughing or laughing are characteristic.  Interestingly pain may radiate to the right shoulder.  Fortunately the Fitz-Hugh-Curtis syndrome does not necessarily cause symptoms.


More recent investigations suggest Chlamydia acting in concert with HPV infection may dramatically increase the risk of cervical cancer.  While HPV infections are extraordinarily common, they appear to need some additional factor to tip a simple bland infection toward cancer.  Synergistic activity of the HPV with Chlamydia may fill that niche.  Years to decades pass prior to the appearance of clinical manifestations.  Further research will establish or refute this association.

In April 2018 at the American Association for Cancer Research annual meeting information from the National Cancer Institute linked antibodies against Chlamydia with a doubling of the rate of ovarian cancer.  Once again further investigation will establish or refute this link.


Women face pregnancy related complications arising as a consequence of both ongoing and former Chlamydia infections.  More than 50% of newborns passing through a birth canal harboring Chlamydia will become infected.  While the mother may be unaware of the organism’s presence, the bacteria can target both the eye, throat and lungs of the infant.

Manifestations of the eye disease, ophthalmia neonatorum, include swelling of the eyelids, discharge and redness usually appearing between 1-2 weeks after delivery.  This time differential distinguishes it from the more immediate chemical conjunctivitis related to eye drops instilled shortly following delivery.  A similar clinical situation due to the bacteria responsible for gonorrhea presents between days 2-5.

Chlamydia frequently infect the newborn’s lungs causing a pneumonitis sometime referred to as afebrile pneumonia syndrome.  This delayed sign of infection customarily remains dormant for 1-3 months before making its appearance known.

Other relatively common issues related to Chlamydia and pregnancy include spontaneous abortion, premature rupture of the membranes and inflammation of the uterus known also as endometritis.  Premature delivery and low birth weight are further issues.


While the incidence among men pales in comparison to women, this mostly relates to an artifact of testing.  Routine guidelines encourage yearly screening for young women but fail to address the issue among men.  Recent investigations suggest only a minimal sex difference exits in the rate of Chlamydia between men and women.  While transmission more readily occurs from men to women, the bacterium seems equally content in either sex.

Only 1 in 2 infected men develop symptoms; the rest continue to shed Chlamydia but experience no symptoms.  Among those with clinical manifestations, urethritis ranks as the most frequent and distressing.  Men complain of urinary difficulties including burning sometimes in addition to a white, cloudy, watery or mucoid discharge.  At times the meatus or penile opening becomes reddened and irritated.

Chlamydia not infrequently attack the epididymis located immediately behind the testicles.  The onset may be gradual; manifestations include pain and discomfort in the scrotum.  Even after treatment, chronic soreness may linger and be mistaken for prostatitis.  Most cases of epididymitis arising in men between ages 14-35 trace their origin to either gonorrhea or Chlamydia.

As with women, proctitis may result; the cause almost always involves receptive sexual relations.  Conjunctivitis and oral infection occur less frequently among men compared to women.


Chlamydia may trigger Reactive Arthritis previously referred to as Reiter’s Syndrome.  The condition generally affects fewer than 5 large joints with a proclivity toward the knee and sacro-iliac joints.  Involvement may also target the ankles and small joints of the fingers and toes.  Heel pain characteristically involves inflammation at the site of insertion of the Achilles tendon into the bone.

This classic condition although infrequent tends to occur with or shortly after Chlamydia infection and attacks men more often than women.  Reactive arthritis mimics rheumatoid arthritis or less commonly osteoarthritis.  The entire classic triad of urethritis, conjunctivitis and arthritis need not be present.  Although generally short lived, the disease may become chronic.


In order to minimize transmission, formal guidelines urge all sexually active women less than age 25 to undergo yearly blood screening.

Others at increased risk are similarly encouraged to routinely seek testing at appropriate intervals.  This includes individuals with a previous sexually transmitted infection, those with new or multiple sex partners and people whose sex partner previously suffered a STI or had multiple sex partners.

Additional indications for testing include sexual intimacy without routine and consistent employment of condoms.  Women seeking emergency contraception and those who also might be pregnant are candidates for testing.

Routine testing of women likely to become pregnant allows early detection, treatment and avoidance of obstetric complications.  At a minimum screening should be undertaken at the first prenatal visit with re-testing during the third trimester irrespective of results from the original examination.

Among men, no uniform recommendations exist for testing.  Experts suggest targeting those at increased risk such as attendees at adolescent healthcare or sexually transmitted disease clinics, men incarcerated in correctional facilities and men having sex with men.  Others who believe themselves to be at high risk for infection should request screening.


Technological advances in screening over the past several decades offers laboratory analysis with little chance of error.  Since the bacteria almost always limit their growth to within human cells, culture poses many challenges.  Culture may be an essential test to document infection when certain legal issues exist.  Unfortunately negative culture results do not guarantee freedom from infection.

Routine laboratory monitoring regularly failed to identify the presence of infection in nearly 50% of those tested with older methods.  Currently the nucleic acid amplification test or NAAT allows accurate and reliable detection of infection.  Approved for use with vaginal or cervical swabs and urine specimens, some commercial products combine testing for both Chlamydia and the organism responsible for gonorrhea.

Samples may be obtained by the health care practitioner or by the individual.  Depending on practice setting and location, this allows the individual being tested to obtain the swab in the privacy of a restroom or while at home much akin to the current standards for colon cancer stool tests.

Unfortunately as with all modern tests, laboratory costs for NAAT tend to range between $100-$150 in routine commercial laboratories unaffiliated with hospitals or medical offices.  A positive test detects the presence of bacterial nucleic acids.  This means that for up to several weeks after successful treatment the results will remain positive.  This indicates retesting shortly after therapy is unreliable and should not be performed.

Lacking the ability to generate energy and obtain certain nutrients, Chlamydia must grow within human cells.  Basically this obligate intracellular bacteria alternates between two forms.  An infectious extracellular spore-like Elementary Body maintains the ability to enter the human host cell.  Once inside, it resides in a special enclosure referred to as a parasitophorous vesicle or simply an inclusion and morphs into a metabolically active but non-infectious Reticulate Body.


Over a short period and multiple replications some of the Reticulate Bodies transform back into Elementary Bodies.  At this stage, the inclusion either merges with the cell membrane and sheds its contents to the extracellular space; alternatively the host cell may simply cease function and degenerate.  Either produces a similar result from the bacteria’s standpoint and allows the cycle to begin anew.

In the extracellular space, Chlamydia trigger the body’s immune reaction which may or may not rise to the level of symptoms.  Despite a lack of clinical awareness, the inflammatory process induced by the bacteria may permanently damage the female reproductive tract.  Screening currently appears the only way to confirm one’s status either as infected or not.


Since the symptoms when present appear non-specific, a variety of other causes must be considered.  Depending on the circumstances the clinical manifestations suggest any of the multiple causes of urethritis, vaginitis, cervicitis, pelvic inflammatory disease, salpingitis, endometritis, prostatitis, epididymitis, orchitis, arthritis,  conjunctivitis and even pneumonitis.  Symptoms may also mimic a urinary tract infection or Bacterial Vaginosis.

Multiple sexually transmitted diseases tend to congregate together.  As a result co-infections frequently occur and include Chlamydia together with herpes, trichomonas, Mycoplasma genitalium, Ureaplasma urealyticum or Candida.

Among the most frequent pairs of STIs are Chlamydia and Neisseria gonorrhoaea the organism responsible for gonorrhea.  Adding to the confusion, either or both of the organisms may remain silent and infect sexual consorts who in turn may or may not become symptomatic but nevertheless may be infectious.

Infection with Chlamydia confers increased susceptibility to HIV transmission.  Chlamydia related irritation of the columnar lined surface of the cervix allows expedited passage of the AIDS virus.


Prevention of Chlamydia infection requires abstinence or a long term monogamous relationship with an individual testing negative for the bacteria.  An alternative but widely ignored choice includes regular use of a barrier method – in other words a condom – for traditional sexual activities combined with a similar method of protection for any oral encounters.

Neither hormonal contraceptives nor intrauterine devices provide protection.  In choosing a condom, only those with natural rubber (latex) or polyurethane suffice.  Natural membrane condoms consisting of animal intestine lack the same protective abilities.  Obviously any product must be properly in place before any sexual intimacy begins.


Uncomplicated infections may be managed with a single oral 1 gram dose of Azithromycin or a seven day course of twice daily doxycycline.  Doxycycline appears slightly more effective.  Second line antibiotics include tetracycline, erythromycin, Levaquin or Oroflox.  Selection depends on convenience, cost and availability.

For pregnant women Azithromycin, erythromycin or amoxicillin are preferred agents.  Doxycycline and tetracycline may harm the fetus.  Doxycycline remains the first choice for rectal disease, men having sex with men and sex workers.


Unlike most diseases where each person at risk should be examined, Expedited Partner Therapy or EPT appears acceptable for Chlamydia.  Those diagnosed with the infection may receive antibiotics to be dispensed to their sexual partners without the need for theses contacts to appear at an office or clinic for evaluation.  Current recommendations suggest treatment for all sex partners within the two months prior to diagnosis.  In the absence of sexual relations within that period, the last sex partner should be treated.

Due to the high risk of multiple diseases including HIV, men having sex with men should be evaluated in person rather than given EPT.


Routine treatment in hospitals of all newborn infants with prophylactic eye drops prevents ophthalmic infection with either Chlamydia or gonorrhea.


Retesting after three months and then yearly as long as risk exists seems wise.  Lifestyle issues suggest individuals with a history of infection will often experience another episode within the first year following treatment.

An enormous number of infectious organisms populate our world and readily take advantage of opportunities presented to them.  Chlamydia remains a prime example.  Similar to the natural flora of the gut, skin and oral cavity, Chlamydia often lurks without eliciting any symptoms.  However the mere presence of this bacteria frequently results in long term complications.  For this reason testing and treatment seems the most prudent option.

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