Chlamydia trachomatis

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Chlamydia trachomatis

• The Biology of a Sexually Transmitted Bacterium

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Chlamydial Life Cycle

• Reticulate body, obligately intracellular in
  eukaryotic cells
• Elementary body, metabolically inert, an
  extracellular spore-like state
• 48-72 hour cycle

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Chlamydial Biology

• Prokaryotes
• Gram negative with LPS
• Lack peptidoglycans?
• Obligate intracellular life cycle

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Chlamydial Genome

• 1.043 million base pairs
• Missing genes for amino acid and
  purine-pyrimidine biosynthesis, anaerobic
  fermentation, and transformation competence
  proteins
• Contains genes for LPS, glycolysis, fatty acid
  and phospholipid synthesis, peptidoglycan
  synthesis

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Chlamydia trachomatis Disease Presentations

• Perinatal infections
• Genitourinary tract infections
• Trachoma

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Chlamydia trachomatis and Sexually Transmitted
Infections

• Urogenital infections cervicitis, urethritis,
  PID, epididymitis/prostatitis
• 4-6 million cases/year, U.S.
• Prevalence highest in young women, 3-11 (age
  15-24)
• Lymphogranuloma venereum

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Serious Consequences of C. trachomatis STI's

• Tubal infertility
• Ectopic pregnancy
• Reactive arthritis (Reiter's syndrome)

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C. trachomatis Perinatal Infections

• Neonatal inclusion conjunctivitis (20-45 of
  infants from infected mothers)
• Infant pneumonia (10-20 of infants from infected
  mothers)

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C. trachomatis and Trachoma

• Blinding conjunctival infection
• 600 million cases worldwide
• Develops over years,
  chronic inflammation
• Endemic in Middle East, Asia

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C. trachomatis Diagnosis

• Serology (MIFmicroimmunofluorescence)
• Culture
• EIAs/DFA (direct fluorescent antibody)
• Direct hybridization
• Nucleic acid amplification (PCR, LCR, others)

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C. trachomatis NA Amplification

• Nucleic acid amplification can be used on urine,
  cervical/urethral specimens
• Vaginal specimens also have been used
• Sensitivity, 90, specificity gt99
• Identifying more male cases, providing easier
  specimen collections

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C. trachomatis Treatment

• Azithromycin,
• (single 1000 mg dose acceptable)
• Tetracyclines (erythromycin in children)

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Chlamydia pneumoniae

• 1983, described as a distinct chlamydial pathogen
• Less than 10 DNA homology with C. trachomatis
• Similar life cycle but different cell wall
  construction

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C. pneumoniae Disease Presentations

• Pharyngitis, bronchitis
• Pneumonia (7-10 of cases)
• Other syndromes (otitis media,
  endocarditis)

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C. pneumoniae and Chronic Diseases

• Atherosclerosis (seroepidemiologic studies,
  experimental disease)
• Asthma
• Neurological disease? (MS, Alzheimers)

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C. pneumoniae Diagnosis

• Serology (MIF microimmunofluorescence
  )
• Culture
• PCR

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C. pneumoniae Treatment

• Azithromycin/clarithromycin (macrolides)
• Erythromycin
• Tetracycline/doxycycline

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Chlamydophila psittaci

• Recently distinguished as a separate genus using
  sequence phylogeny
• Zoonosis, typically from pet birds, occupational
  exposure
• 80 cases/year in the U.S

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Chlamydophila psittaci Clinical Disease/Dx/Tx

• Severe pneumonia
• Endocarditis, other systemic presentations
• Diagnosis by serology, culture
• Prolonged therapy with tetracycline