1. Mycoplasma and Ureaplasma

2. Family: Mycoplasmataceae
Genus: Mycoplasma
Species: M. pneumoniae
Species: M. hominis
Species: M. genitalium
Genus: Ureaplasma
Species: U. urealyticum

3. Diseases Caused by Mycoplasma
N.B. Other organisms infect humans but their disease association is not known.

4. Morphology and Physiology
Smallest free-living bacteria ( :m)
Small genome size
Require complex media for growth
Facultative anaerobes
Except M. pneumoniae - strict aerobe
Lack a cell wall
Grow slowly by binary fission
“Fried egg” colonies
M. pneumoniae colonies have a granular appearance

5. “Fried Egg” Colonies of Mycoplasmas

6. Morphology and Physiology
Smallest free-living bacteria
Small genome size
Require complex media for growth
Facultative anaerobes
Except M.. pneumoniae - strict aerobe
Lack a cell wall
Grow slowly by binary fission
“Fried egg” colonies
Ureaplasma - T strains
Require sterols for growth

7. Differentiation of Species
M. pneumoniae - glucose
M. hominis - arginine
U. urealyticum - urea
M. genitalium - difficult to culture

8. Pathogenesis - Mycoplasma
Adherence
P1 pili (M. pneumoniae)
Movement of cilia ceases
Clearance mechanism stops resulting in cough
Toxic metabolic products
Peroxide and superoxide
Inhibition of catalase
Immunopathogenesis
Activate macrophages
Stimulate cytokine production
Suprerantigen (M. pneumoniae)

9. Mycoplasma pneumoniae
Tracheobronchitis
Atypical pneumonia (walking pneumonia)

10. Epidemiology - M. pneumoniae
Occurs worldwide
No seasonal variation
Proportionally higher in summer and fall
Epidemics occur every 4-8 year

11. Epidemiology - M. pneumoniae
Spread by aerosol route (Confined populations)
Disease of the young (5-20 years), although all ages are at risk

12. Epidemiology - M. pneumoniae
Estimated pneumonia in USA per year – 2 million
Estimated respiratory disease in USA per year – 20 million
Non-reportable disease

13. Clinical Syndrome - M. pneumoniae
Tracheobronchitis
70-80% of infections
Pneumonia
Approximately 10% of infections
Mild disease but long duration
“Primary atypical pneumonia”
“Walking pneumonia”

14. Clinical Syndrome - M. pneumoniae
Incubation weeks
Fever, headache and malaise
Persistent non-productive cough
Respiratory symptoms
Radiological signs precede symptoms
Organisms persist
Slow resolution
Rarely fatal

15. Immunity - M. pneumoniae
Complement activation
Alternative pathway
Phagocytic cells
Antibodies
IgA important
Delayed type hypersensitivity
More severe disease (immunopathogenesis)

16. Laboratory Diagnosis - M. pneumoniae
Microscopy
Difficult to stain
Can help eliminate other organisms
Culture (definitive diagnosis)
Sputum (usually scant) or throat washings
Special transport medium needed
Must suspect M. pneumoniae
May take 2-3 weeks

17. Laboratory Diagnosis - M. pneumoniae
Serology
Complement fixation
May take 4-6 weeks
Fourfold rise in titer
Cold agglutinins
1/3 - 2/3 of patients
I antigen
Appear first
Non-specific
Presumptive diagnosis
ELISA
Not commercially available

18. Laboratory Diagnosis - M. pneumoniae
Molecular diagnosis
PCR-based tests are being developed and these are expected to be the diagnostic test of choice in the future.

19. Treatment and Prevention M. pneumoniae
Tetracycline or erythromycin
Newer fluoroquinolones
Can’t use cell wall synthesis inhibitors
Prevention
Avoid close contact
No vaccine

20. M. hominis, M. genitalium and U. urealyticum
Clinical syndromes
M. hominis - pyleonephritis, pelvic inflammatory disease and postpartum fever
M. genitalium - nongonococcal urethritis
U. urealyticum - nongonococcal urethritis
Epidemiology
Colonization at birth - usually cleared
Colonization with M. hominis - 15%
Colonization with U. urealyticum - 45% -75%
Colonization with M. genitalium - ??

21. M. hominis, M. genitalium and U. urealyticum
Laboratory diagnosis
Culture (except M. genitalium)
Treatment and prevention
Treatment
Tetracycline or erythromycin
Prevention
Abstinence or barrier protection
No vaccine