chlamydia

武功密笈

小黃藏書

chlamydia

~ Chlamydial Infection in Pregnancy ~

　

§ Risk Factors for C trachomatis infections:

j Young age

k Single marital status

l Young age at onset of coitus

m Multiple sex contacts

n Mucopurulent cervicitis

o Oral contraceptive use

　

§ Serious consequences of C trachomatis infections:

³ In nonpregnant women:

j Salpingitis

k Acute urethral syndrome

l Bartholinitis

m Proctitis

n Tubal factor infertility

o Chronic pelvic pain

³ In pregnant women:

j Postpartum and postabortal endometritis

k Transmission to the neonate through vertical transmission from endocervical infection:

- Conjunctivitis (18% to 50%)

- Pneumonia (11% to 18%)

l Spontaneous abortion

m Poor prognosis of in vitro fertilization

n Premature rupture of membrane

o Preterm labor

p Low birthweight

³ In men:

j Urethritis

k Epididymitis

　

§ Pathophysiology:

³ C trachomatis is an obligate intracellular bacterium that depends on host cells

for nutrients and energy.

³ C trachomatis is transmitted to the glandular epithelium of the endocervix and

can persist there for many months. Ascent to the endometrium, the fallopian

tubes, and peritoneal cavity can occur, even in the absence of symptoms.

ø Risk factors for development of upper-tract disease are poorly defined:

- Repeated exposure to sexually transmitted organisms, as a result of high-risk sexual behavior.

- Vaginal douching: mechanically introducing the organism to upper-tract

ø Cause of tubal obstruction after C trachomatis infection:

- Delayed hypersensitivity reaction after repeated exposure to C trachomatis

³ Infection occurs as the following sequence:

Metabolically inactive elementary body

Attaching to the host cells

Ingested by host cells with phagocytosis

Metabolically active elementary body

Dividing

Reticulate body

Dividing for 8-24 hours

Elementary bodies

48-72 hours later

Host cells bursts or releases the pathogens to spread infection

　

§ Clinical manifestations:

³ During recent decades, genital Chlamydial trachomatis infection has become

the most prevalent sexually transmitted bacterial pathogen in the United

States.

³ Most genital C trahomatis infections are asymptomatic.

The remainder are associated with non-specific symptoms such as vaginal

discharge, intermenstural bleeding, dysuria, and pelvic pain.

³ A negative endocervical C trachomatis culture does not exclude infection of

the urethra or fallopian tubes.

　

§ Diagnosis:

³ Cell culture:

The “gold standard” for diagnosis

Dependent on the viability of the organisms in transport media

- False negative results can occur if cells die during transport from the office to the laboratory.

Sensitivity: 70% to 80%

³ DFA (direct fluorescent antigen testing):

Sensitivity: 90%

Specificity: 98%

³ EIA (enzyme immunoassay):

Sensitivity: 92% to 97%

Specificity: 67% to 91%

The EIA’s low specificity makes it necessary to confirm positive results with another test,

usually the DFA test.

³ Rapid enzyme tests:

Lower sensitivity and specificity

May be performed in the office

³ DNA detection:

By PCR (polymerase chain reaction) or LCR (ligase chain reaction)

May be used in specimens from cervical swabs, urine, or vaginal introitus swabs

Sensitivity: 98%

Specificity: 99%

　

§ Treatment:

³ First-line treatment in pregnancy:

Erythromycin base 500mg qid for 7 days

If GI disturbance (leading to discontinuance of therapy 15% to 20%)

Amoxicillin (Amoxil^R) (250) 2# tid for 7 days

or

Azithromycin 1g for single-dose

³ Medications ought to be avoided in pregnancy:

Erythromycin estolate: risk of drug-related hepatotoxicity

Doxycycline: altering fetal tooth and bone development

Ofloxacin (Tarivid^R): associated with fetal cartilage defects in animal studies

³ For successful treatment:

The sexual contacts of infected women should be treated.

A routine test-of-cure (culture test) 3 weeks after treatment is recommended

³ Outcome associated treatment of C trachomatis infections:

Improved pregnancy outcomes:

Reduction in preterm PROM, preterm labor, SGA infants, and low-birth-weight infants

Improved neonatal survival

　

§ Neonatal chlamydial infections:

³ Inclusion conjunctivitis:

Seen in 35% to 50% of infants born to untreated mothers with cervical C trachomatis

infection

Onset of symptom/sign: 5^th to 12^th days of life

Clinical findings:

mucoid discharge Ò more purulent discharge

Ò edema of the eyelids with erythema of both the palpebral and bulbar conjunctivas

³ Chlamydial pneumonia:

Seen in 11% to 20% of infants born to untreated mothers

Onset of symptom/sign: 2^nd to 6^th weeks of life

Clinical findings: tachycardia with a staccato cough and rales

CxR: hyperexpansion, with diffuse interstitial and patchy alveolar infiltrates

³ Treatment of neonatal Chlamydial infections:

Oral erythromycin to clear all colonization sites, including the nasopharynx, which is not

accomplished with only topical antibiotic therapy.

³ Neonatal prophylaxis for Chlamydial conjunctivitis:

Most effectively method is screening and treating pregnant women before delivery

　

§ References:

1. Chlamydia trachomatis infections in pregnancy. Abner P. Korn, MD.

Contemporary OB/GYN April 2000: 65-82

Filename: Chlamydial Infection in Pregnancy