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Chlamydia trachomatis

Chlamydia trachomatis. The Biology of a Sexually Transmitted Bacterium. Chlamydial Life Cycle. Reticulate body, obligately intracellular in eukaryotic cells Elementary body, metabolically inert, an extracellular spore-like state 48-72 hour cycle. Chlamydial Biology. Prokaryotes

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Chlamydia trachomatis

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  1. Chlamydia trachomatis The Biology of a Sexually Transmitted Bacterium

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

  3. Chlamydial Biology • Prokaryotes • Gram negative with LPS • Lack peptidoglycans? • Obligate intracellular life cycle

  4. 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

  5. Chlamydia trachomatis: Disease Presentations • Perinatal infections • Genitourinary tract infections • Trachoma

  6. 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

  7. Serious Consequences of C. trachomatis STI's • Tubal infertility • Ectopic pregnancy • Reactive arthritis (Reiter's syndrome)

  8. C. trachomatis Perinatal Infections • Neonatal inclusion conjunctivitis (20-45% of infants from infected mothers) • Infant pneumonia (10-20% of infants from infected mothers)

  9. C. trachomatis and Trachoma • Blinding conjunctival infection • 600 million cases worldwide • Develops over years, chronic inflammation • Endemic in Middle East, Asia

  10. C. trachomatis: Diagnosis • Serology (MIF=microimmunofluorescence) • Culture • EIAs/DFA (direct fluorescent antibody) • Direct hybridization • Nucleic acid amplification (PCR, LCR, others)

  11. C. trachomatis: NA Amplification • Nucleic acid amplification can be used on urine, cervical/urethral specimens • Vaginal specimens also have been used • Sensitivity, 90%+, specificity >99% • Identifying more male cases, providing easier specimen collections

  12. C. trachomatis: Treatment • Azithromycin, (single 1000 mg dose acceptable) • Tetracyclines (erythromycin in children)

  13. 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

  14. C. pneumoniae: Disease Presentations • Pharyngitis, bronchitis • Pneumonia (7-10% of cases) • Other syndromes (otitis media, endocarditis)

  15. C. pneumoniae and Chronic Diseases • Atherosclerosis (seroepidemiologic studies, experimental disease) • Asthma • Neurological disease? (MS, Alzheimer’s)

  16. C. pneumoniae: Diagnosis • Serology (MIF = microimmunofluorescence) • Culture • PCR

  17. C. pneumoniae: Treatment • Azithromycin/clarithromycin (macrolides) • Erythromycin • Tetracycline/doxycycline

  18. 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

  19. Chlamydophila psittaci: Clinical Disease/Dx/Tx • Severe pneumonia • Endocarditis, other systemic presentations • Diagnosis by serology, culture • Prolonged therapy with tetracycline

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