Chapter 21 – Chlamydia, Mycoplasma, & Ureaplasma Species

1. Chapter 21 – Chlamydia, Mycoplasma, & Ureaplasma Species MLAB 2434 – Clinical Microbiology Cecile Sanders & Keri Brophy-Martinez

2. Chlamydia Characteristics • Unique growth cycle because they are deficient in independent energy metabolism; therefore they are obligate intracellular parasites • Replication involves elementary body (EB) and reticulate body (RB)

3. Life Cycle of Chlamydia • EB infects host cell by inducing energy-requiring active phagocytosis • EB organize into large, reticulating initial bodies, which divert the cells’ synthesizing functions to their own needs and begin to multiply by binary fission • Organisms begin reorganizing into infective EBs. • Disrupted host cell dies, releasing new EBs

4. Life Cycle of Chlamydia

5. Chlamydia pneumoniae • Most recognized species of Chlamydia • Important respiratory pathogen (acute respiratory disease, pneumonia, and pharyngitis) • Implicated in asthma • Risk factor for Guillain-Barre’ syndrome

6. Chlamydia pneumoniae (cont’d) • Common (50% of adults have antibodies) • College age students most susceptible • Reinfection common • Prolonged sore throat and hoarseness, followed by flu-like lower respiratory symptoms • Can be following by pneumonia and bronchitis • Third most common respiratory infection

7. Chlamydia pneumoniae (cont’d) • If cultured, must be in cells (obligate intracellular pathogen) and then visualized with fluorescein-conjugated antibodies • Serologic tests are method of choice for detection (Four-fold rise in titer)

8. Chlamydia trachomatis • Most commonly sexually transmitted bacterial pathogen in U.S. • Only HPV is a more commonly sexually transmitted disease • Adult males • Non-gonococcal urethritis (NGU) • Epididymitis and prostatitis

9. Chlamydia trachomatis (cont’d) • Adult females • Urethritis, follicular cervicitis, endometritis, proctitis, salpingitis, PID and perihepatitis (Fitz-Hugh-Curtis syndrome) • Major cause of sterility in U.S. • May be transmitted to newborns during delivery

10. Chlamydia trachomatis (cont’d) • Other sites of infection • Trachoma – infection of the conjunctiva, resulting in scarring and blindness (Mostly in India and Egypt) • Lymphogranuloma verereum – STD found in immigrants

11. Chlamydia trachomatis (cont’d) • Laboratory Diagnosis • Direct microscopic examination to find EBs (p. 646) • Cell culture • Enzyme immunoassay • Nucleic acid probes with and without amplification (PCR) • Serologic (antibody) assay

12. Chlamydia psittaci • Causes psittacosis (parrot fever) • Identification based on history of close contact with birds and serologic evaluation

13. Mycoplasma and Ureaplasma Species • General Characteristics • Once thought to be viruses because of size • Mycoplasmas are the smallest free-living organism in nature • Three human pathogens • Mycoplasma pneumoniae - respiratory • Mycoplasma hominis - urogenital • Ureaplasma urealyticum - urogenital

14. Mycoplasma and Ureaplasma Species (cont’d) • Pleomorphic organisms – do not have a cell wall (resistant to cell-wall-active antibiotics) • Slow growing, highly fastidious, facultative anaerobes • Require complex media for growth

15. Clinical Infections • Mycoplasma pneumoniae • Causes bronchitis, pharyngitis, or primary atypical pneumonia (a.k.a. “walking pneumonia”) • Usually infects school-age children and young adults in close quarters (dorms, military barracks, etc.) • 50% of infections produce “cold agglutinins” • Most often diagnosed by serologic evaluation

16. M. hominis & U. urealyticum • Most often associated with urogenital tract infections • May be isolated from asymptomatic individuals • Can be transmitted to the fetus at delivery

17. Laboratory Diagnosis • Cultures must be delivered immediately to the lab, because the organisms are very susceptible to drying • Should be placed in transport media • If not plated immediately, should be frozen at -70°C • Most infections detected via serologic evaluation