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 Gram negative with LPS Lack peptidoglycans? Obligate intracellular life cycle

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

Chlamydia trachomatis: Disease Presentations Perinatal infections Genitourinary tract infections Trachoma

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

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

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

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

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

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

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

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

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

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

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

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

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

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