Chlamydia trachomatis The Biology of a Sexually Transmitted Bacterium ChlamydiaChlamydia ♦♦ThreeThree speciesspecies areare humanhuman pathogenspathogens ♦♦ChlamydiaChlamydia trachomatistrachomatis ♦♦ChlamydiaChlamydia pneumoniaepneumoniae ♦♦ChlamydophilaChlamydophila psittacipsittaci 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.