Chlamydia species infection
Introduction
The family Chlamydiaceae have 3 medically important species
1. Genus Chlamydia:
Chlamydia trachomatis
2. Genus Chlamydophilia:
Chlamydia pneumoniae
Chlamydia psittaci
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Introduction 2
Chlamydia species are small obligate intracellular parasites which contain DNA, RNA and ribosome and make their own proteins and nucleic acids. However they are unable to make their own ATP.
They have a special growth cycle and replicate by binary fission. They possess a rigid cell wall like gram negative bacteria, but very difficult to stain as such.
Chlamydia are sensitive to antibiotics and respond to wide-spectrum antibiotics, but not to penicillin (because they lack peptidoglycan).
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Introduction 3
Chlamydia trachomatis only infects human epithelial cells (except biovar mouse). They are typically coccoid, or rod shaped and require growing cells to remain viable.
Three biovars (biological variants) exist:
•Biovar Trachoma (14 serologic types)
•Biovar lymphogranuloma venereum, LGV (4 serologic types)
•Biovar mouse
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Pathogenesis
Chlamydia species invades the body via minute abrasions and lacerations
• Primarily infect non-ciliated columnar, cuboidal, or transitional epithelial cells (found in the urethra, endocervix, endometrium, fallopian tube, anorectum, respiratory tract, conjunctiva)
• LGV biovar replicates in mononuclear phagocytes in lymphatic system (forming granuloma, abscesses or sinus tracts in lymph nodes draining the site of primary infection)
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Pathogenesis 2
• This infection stimulates a severe inflammatory response (attracting neutrophils, lymphocytes and plasma cells) causing destruction of cells during replication.
• Re-infection induces a vigorous inflammatory response with subsequent tissue damage (blindness and sterility).
• It stimulates the infiltration of polymorphonuclear cells and lymphocytes which leads to lymphoid follicle formation and fibrotic changes.
• There is no long-lasting immunity acquired after infection.
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Clinical presentations
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Chlamydia trachomatis
This infections only occurs in humans, two biovars (trachoma and LGV) and 19 serotypes.
Serotypes Disease
A to C Trachoma
D to K Urethritis, cervicitis Inclusion conjunctivitis Neonatal conjunctivitis Infant pneumonia
L1 to L3 Lymphogranuloma venereum
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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1. Trachoma
This is a chronic suppurative eye disease caused by serotypes A, B, Ba and C.
Follicular conjunctivitis → scar → corneal ulceration → pannus formation (invasion of vessels into the cornea) → blindness.
Transmission is by transfer of eye discharge by hands, contaminated clothing, flies or by passage through an infected birth canal.
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Trachoma 2
This is a worldwide infection primarily in areas where there is poor sanitation and overcrowding, infections occur most commonly in the children.
It is endemic in the Middle East, North Africa and India (dry and sandy regions).
It is the leading global cause of blindness (500 million infected, 7 to 9 million blinded).
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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2. Sexually transmitted infections
Venereal infections are caused by serotypes D to K about 50 million cases are reported worldwide.
It is the most common sexually transmitted bacterial infection in the United states of America, where 2.8 million new cases are reported annually, largely urethritis in males.
In men about 25% present asymptomatically with nongonococcal urethritis (NGU).
In women, 80% present asymptomatically with Bartholinitis, cervicitis and pelvic inflammatory disease, which can lead to sterility and ectopic pregnancy.
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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3. Inclusion Conjunctivitis
Adult inclusion conjunctivitis presents as an acute follicular conjunctivitis with mucopurulent eye discharge. This mostly occurs in sexually active adults (between the ages of 18-30 years) with genital infection with serotypes A, B, Ba, D to K. Mode of transmission is by auto-inoculation between oral and genital anatomy.
About 25% infants’ infection are acquired from mothers with active genital infections. There is a muco-purulent eye discharge from the 4th day after birth.
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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4. Infant Pneumonia
This is a long term (>12 months) disease course and if untreated infants are at risk of Chlamydia trachomatis infant pneumonia.
This is a diffuse interstitial pneumonia that occurs in 10-20% of infants that are exposed to the pathogen at birth.
They present with rhinitis and staccato cough (but are afebrile).
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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5. Lymphogranuloma Venerum
This is a chronic sexually transmitted infection caused by Chlamydia trachomatis L1, L2, L2a, L3. It is more common in men, and male homosexuals are the major reservoir.
Presents as small, painless lesions at site of infection (genitalia) associated with fever, headache and myalgia. There is swelling of regional (inguinal) lymph nodes making painful buboes which may later rupture. Proctitis is common in women.
It may resolve spontaneously or progress to ulceration or genital elephantiasis.
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Laboratory diagnosis
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Chlamydophilia pneumoniae
The organism was first isolated from the conjunctiva of a child in Taiwan - TWAR stain. It turned out to be an important cause of bronchitis, pneumonia and sinusitis.
It is a common cause of atypical community acquired pneumonia in 3-10% of adult population and transmitted from person-to-person by respiratory secretions.
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Chlamydophilia pneumoniae
Most infections are asymptomatic or mild with a persistent cough.
It cannot be differentiated from other atypical pneumonia - Mycoplasma pneumoniae, Legionella pneumophila and respiratory viruses.
Detected in atherosclerotic lesions in blood vessels. However, the role in the development of atherosclerosis is not clear.
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Laboratory diagnosis
• Diagnosis is very difficult
• Organism does not grow in cell lines.
• Nucleic Acid Amplification Techniques (NAATs) are used.
• Complement fixation test (CFT) may be used but it is not specific.
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Treatment
Azithromycin 1 g orally in a single dose OR
Doxycycline 100 mg orally twice daily for 7 days.
Erythromycin 500 mg orally 4 times a day for 7 days, OR
Ofloxacin 300 mg orally twice a day for 7 days, OR
Levofloxacin 500 mg orally once a day for 7 days.
Treatment coupled with improved sanitation to prevent reinfection is the best way to control infection.
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Thank you
Thank you for paying attention
Dr. Jonah Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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