1. Chlamydia
Dr. Hala Al-Daghistani

2. C. trachomatis C. psittaci C. pneumoniae
Chlamydia is a genus of pathogenic bacteria that are obligate intracellular parasites of mammals and birds.
Classification – order chlamydiales – contains one medically important genus – chlamydia
Chlamydia infections are the most common bacterial Sexually transmitted diseases in humans and are the leading cause of Infectious blindness worldwide.
Reported rates 3 times higher in females than in males.
contain DNA and RNA, and ribosomes, lack ATP, biosynthetic pathways, non motile. Multiply in the cytoplasm of the host cell. Three important spp.,
C. trachomatis
C. psittaci
C. pneumoniae

3. Transmission Transmission is sexual or vertical Highly transmissible
Incubation period 7-21 days
Significant asymptomatic reservoir exists in the population
Re-infection is common
Perinatal transmission results in neonatal conjunctivitis in 30%-50% of exposed babies

4. Have a complex developmental cycle
The infectious form is called an Elementary Body (EB) which is circular in form and is taken into the cell by induced phagocytosis.
Inside the phagocytic vesicle replication takes place.
Over the next 6-8 hours, the EB reorganizes into the noninfectious, but metabolically active Reticulate Body (RB) which is larger and less dense than the EB.
For hours the RB synthesized new materials and divides by binary division to form Inclusion Bodies that reorganize and condense into EBs.
Between hours, the cell lyses and releases the EB which begin the cycle again.

5. Elementary body Reticulate Body 0.25 - 0.3 um diameter
electron-dense nucleoid
Released from ruptured infected cells. Human to human
& bird to human.
Reticulate Body
Intracytoplasmic form um
Replication and growth. ( Inclusion body )
without a dense center.

7. Chlamydia inclusion bodies

8. Chlamydiaceae Family Species (genus) Disease
C. Trachomatis (many serotypes)
Trachoma, NGU, PID, neonatal conjunctivitis, inclusion conjunctivitis,
Infant pneumonia, LGV
C. Pneumoniae (TWAR) Taiwan acute respiratory agent 
Pharyngitis, bronchitis, pneumonia
C. psittaci
(many serotypes)
Psittacosis(influenza-like illness)

9. Clinical significance
1. Chlamydia trachomatis
Genital tract infection– is sexually transmitted and frequently found concomitantly with N. gonorrhoeae (In males symptoms include urethritis, dysuria and it sometimes progresses to epididymitis; In females symptoms include mucopurulent cervical inflammation which can progress to salpingitis and PID).
Inclusion conjunctivitis –occurs in both newborns and adults and a genital tract infection is the source of the infection. It is self-limited conjunctivitis which heals with no scarring. Newborns are infected during the birth process, with a mucopurulent discharge. In adults causes an acute follicular conjunctivitis with little discharge (autoinoculation).
Trachoma, greatest cause of blindness in underdeveloped countries. (Transmission is by direct contact and in poor, less developed countries, children may be infected in the first three months of life.
Lymphogranuloma venereum is a venereal disease that occurs in poor, tropical areas. painless lesion occurs at the site of entry with symptoms of regional suppurative lymphadenopathy (buboes)

10. Chlamydia psittaci Chlamydia pneumoniae
naturally infects avian species causing mild to severe illness.
In man causes psittacosis (ornithosis) and is acquired by contact with an infected animal.
Infection can range from subclinical to fatal pneumonia.
Most commonly causes an Atypical pneumonia with fever, chills, dry cough, headache, sore throat, nausea, and vomiting.
Chlamydia pneumoniae
This bacterium was first recognized as a respiratory pathogen, after isolation from pharyngitis case.
Pneumonia or Bronchitis, gradual onset of cough with little or no fever. Less common presentations are Pharyngitis, Laryngitis, and Sinusitis

12. Pathogenesis - Chlamydiae have a hemagglutinin that may facilitate attachment to cells. - An endotoxin-like toxin has been described.
Laboratory Diagnosis
Culture
Non-culture tests
Nucleic Acid Amplification Tests
Non-Nucleic Acid Amplification Tests including Direct fluorescent antibody (DFA), Enzyme immunoassay (EIA), and Nucleic acid hybridization (NA probe)
Serology

13. Nature of the infection
Prevention
Nature of the infection
Chlamydia is commonly asymptomatic in men and women.
In women, there is an increased risk of upper reproductive tract damage with re-infection.
Transmission issues
Abstain from sexual intercourse until partners are treated and for 7 days after a single dose of azithromycin