Chlamydia trachomatis The Biology of a Sexually Transmitted

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 purinepyrimidine 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