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