1. Mycoplasma and Ureaplasma
Dr. Hala Al Daghistani

2. MYCOPLASMA Smallest free-living micro organisms, lack cell wall.
Many can pass through a bacterial filter.
Called “pleuropneumonia like organisms”(PPLO).
1956- PPLO replaced by Mycoplasma.
Myco : fungus like branching filaments
Plasma : plasticity
highly pleomorphic – no fixed shape or size .

3. Morphology and Physiology
Small genome size (M. pneumoniae is ~800 Kbp)
Require complex media for growth including sterols
Facultative anaerobes
Except M. pneumoniae - strict aerobe
are resistant to penicillins, cephalosporins and vancomycin, etc.
Grow slowly and reproduced by binary fission
Doubling time can be as long as hours, extended incubation needed

4. Mycoplasmas of Humans Parasitic Established pathogens: M. pneumonia
Presumed pathogens: M. hominis, U. urealyticum
Non pathogenic: M. orale, M. buccale, M. genitalium, M. fermentans
Saprophytic – present mainly on skin & in mouth.

5. Pathogenicity
Produce surface infections – adhere to the mucosa of respiratory, gastrointestinal & genitourinary tracts with the help of adhesin.
Two types of diseases:
Atypical Pneumonia
Genital infections

6. Adherence
P1 pili (M. pneumoniae)
Toxic metabolic products
Peroxide and superoxide
Inhibition of catalase produced by WBCs
Immunopathogenesis
Stimulate cytokine production
Inflammatory cells migrate to infection and release TNF-a then IL-1 and IL-6

7. Mycoplasma pneumoniae
Also called Primary Atypical Pneumonia/ Walking pneumonia.
Seen in all ages
Incubation period: 1-3 weeks
Transmission: airborne droplets of nasopharyngeal secretions, close contacts (families, military recruits).
Gradual onset with fever, malaise, chills, headache & sore throat.
Severe cough with blood tinged sputum
Complications: otitis media, meningitis, encephalitis, hemolytic anemia

8. Diseases Caused by Mycoplasma
Organism Disease M. pneumoniae Atypical pneumonia , Upper respiratory tract disease, tracheobronchitis M. hominis Genital infection, Pyelonephritis, pelvic inflammatory disease, postpartum fever M. genitalium Nongonococcal urethritis U. urealyticum Nongonococcal urethritis, (pneumonia and chronic lung disease in premature infants) Both M. hominis, U. urealyticum Also associated with infertility, abortion, postpartum fever, chorioamnionitis & low birth weight infants

9. Laboratory Diagnosis Specimens – throat swabs, respiratory secretions.
Highly pleomorphic
Gram negative, but better stained with Giemsa, Dienes’ stain,
Isolation of Mycoplasma (Culture)
Enriched medium containing 20% horse or human serum (as a source of cholesterol & other lipids)
Incubate aerobically for days with 5–10% CO2 at 35-37°C
Typical “fried egg” appearance of colonies - Central opaque granular area of growth extending into the depth of the medium, surrounded by a translucent peripheral zone.
Produce beta hemolytic colonies

10. Dr Ekta,Microbiology, GMCA
Fried egg colonies
Dr Ekta,Microbiology, GMCA

11. Identification of Isolates
Growth Inhibition Test – inhibition of growth around discs impregnated with specific antisera.
Immunofluorescence
Molecular diagnosis
Non specific serological tests – cold agglutination tests (Abs agglutinate human group O red cells at low temperature, 4C). 1:32 titer or above is significant.

12. Dr Ekta,Microbiology, GMCA
19/02/2008
Dr Ekta,Microbiology, GMCA