1. Mycoplasmas and Actinomycetes
Presented by
د. آصف احمد محمد جي مان فطاني
بكاالوريوس الطب والجراحة (جامعة الملك عبدالعزيز)
ماجستير الكائنات الدقيقة الطبية والجزيئية (جامعة مانشستر)
دكتوراه الكائنات الدقيقة الطبية (جامعة مانشستر – بريطانيا)
Dr Asif Jiman-Fatani, MB ChB, MSc, PhD (UK)
Assistant Professor in Medical Microbiology,
Faculty of Medicine, King Abdulaziz University
Consultant Microbiologist
Head, Clinical Microbiology Laboratories
King Abdulaziz University Hospital

2. MYCOPLASMAS Characteristics
Lacking cell wall
Resistant to antibacterials that inhibit cell wall synthesis
Gram’s stain : Not useful
Pleomorphic
Cannot be classified as either cocci or bacilli
Enclosed in a plasma membrane
Lipid bilayer membrane containing sterols
Smallest free-living organisms
Pass through bacteriologic filters
Can be cultured in vitro.

3. MYCOPLASMAS Mycoplasma pneumoniae → Atypical Pneumonia
Mycoplasma hominis → STI: Non-gonococcal Urethritis, Cervicitis, PID
Ureaplasma urealyticum → STI: Non-gonococcal Urethritis, Cervicitis, PID

4. Mycoplasma pneumoniae (Eaton’s reagent) Habitat and Transmission
Habitat is the human respiratory tract.
Transmission : Respiratory droplets.

5. Mycoplasma pneumoniae Pathogenesis
P1 adhesion protein
M. pneumoniae binds to respiratory ciliated epithelium
Adherence results in ciliostasis & cell destruction → reduced ciliated clearance
Bacteria then gain access to the lower respiratory tract
Produces hydrogen peroxide : may damage the respiratory tract.
No exotoxins produced.
No endotoxin because there is no cell wall.

6. Mycoplasma pneumoniae Diseases
Atypical pneumonia :
Clinical Features: Fever – Dry cough “or scantily productive cough”
Walking pneumonia
Complications: Mild hemolytic anaemia
Upper Respiratory Diseases :
Otitis Media
Pharyngitis
Tracheobronchitis

7. Mycoplasma pneumoniae Laboratory Diagnosis
Specimens: but scanty sputum
Gram stain : not useful.
Culture: on special bacteriologic media. Takes at least 10 days to grow (too long to be clinically useful).
Colonie: Fried egg appearance
Serology
A cold-agglutinin titer of 1:128 or higher is indicative of recent infection
Cold agglutinin: IgM autoantibodies against red blood cells that agglutinate these cells at 4 °C but not at 37 °C
Complement fixation test for antibodies to Mycoplasma pneumoniae is more specific.
PCR
Note : Diagnosis relies on clinical findings

8. Mycoplasma pneumoniae Treatment
Erythromycin or …
Tetracycline.
Prevention
No vaccine or drug is available

10. Genital Mycoplasmas
Mycoplasma hominis → STD: Non-gonococcal Urethritis, Cervicitis, PID
Ureaplasma urealyticum → STD: Non-gonococcal Urethritis, Cervicitis, PID

12. Actinomycetes

13. Actinomycetes Gram positive bacteria Filamentous branching bacilli
Superficially resemble fungi on morphologic grounds
They are prokaryotes
Has bacterial size

14. Actinomycetes Few are pathogenic to human, the most important are :
Actinomyces israelii
Nocardia astroides

15. ACTINOMYCETES Actinomyces israelii
Gram-positive filamentous branching bacilli
Anaerobic
Grows slowly

16. Actinomyces israelii Habitat and Transmission
Habitat : Found as scanty normal commensal in the:
Mouth, especially anaerobic crevices around the teeth
Colon
Vagina
Disease begins when these normal flora enter adjacent sterile tissue e.g, by trauma, surgery
Transmission into tissues occurs during :
Dental extraction - Poor dental hygiene
Trauma (mouth – uterus)
Organism also aspirated into lungs, causing thoracic actinomycosis.

17. Actinomyces israelii Pathogenesis
Infections occur in both :
Normal hosts
Immunocompromised patients
No toxins or virulence factors known.
Organism forms sinus tracts that open onto skin and contain yellow “sulfur granules”
Sulfur granules : are made up of large masses of
organisms microcolonies of filamentous bacteria

18. Actinomyces israelii Disease
Actinomycosis (abscesses with draining sinus tracts)
Chronic suppurative abscess
The lesion (Mycetoma) :
Begins as a hard red swelling
Ddevelops slowly, becomes filled with pus
Draining with sinus formation
Sites:
Oral-facial abscesses (> 50% of cases)
Often associated with trauma or dental extraction
Abdominal infections:
Abscess. Many after appendicitis
Uterine infection :
Associated with intrauterine contraceptive devices
Chest infection
Invasive infections in immunocompromised patients

19. Actinomyces israelii Laboratory Diagnosis
Specimen: Pus
Filaments may aggregate to form visible granules “Sulphur granules” in pus: Yellowish particles
No sulphur
Microscopy:
Sulfur Granules : Gram-positive filamentous, branching rods
Culture:
Anaerobic culture on blood agar plate (10 days)
Molar teeth colonies
No serologic tests.

20. Actinomyces israelii Treatment
Penicillin
For up to 3-12 months
Tetracyclin or Clindamycin
For penicillin-allergic patients
Surgical drainage
Prevention
Good oral hygiene
Prophylactic antibiotics in association with GIT or oral trauma or surgery
No vaccine is available.

21. ACTINOMYCETES
Nocardia asteroides

22. Nocardia asteroides Disease
Nocardiosis (especially lung and brain abscesses).

23. Nocardia asteroides Characteristics
Gram positive filamentous, branching rods.
Aerobic
Acid-fast (weakly)

24. Nocardia asteroides Habitat and Transmission
Habitat is the soil.
Transmission :
Airborne particles, which are inhaled into the lungs
Implantation : by contamination of skin wounds

25. Nocardia asteroides Pathogenesis
Predisposing Factors:
Immunosuppression
HIV
Cancer
No toxins or virulence factors known.

26. Nocardia asteroides Diseases
Diseases: Abscesses in:
Lung
Brain
Kidney

27. Nocardia asteroides Laboratory Diagnosis
Specimen : Pus
Microscopy :
Gram-stained smear : Gram positive filamentous, branching rods
Ziehl-Neelsen stain (modified) : weakly AFB (branching)
Culture :
Aerobic culture on blood agar plate.
No serologic tests.

28. Nocardia asteroides Treatment
Sulfonamides
Long duration
Nocardia is resistant to penicillin
Prevention
No vaccine is available.

29. Differences between Actinomyces israelii & Nocardia astroides
Aerobic
Anaerobic
Growth Atmosphere
Soil
Mouth, Colon, Vagina
Habitat
Inhalation or implantation
Trauma (Tooth extraction, Jaw fracture, Intrauterine Contr. Dev.)
Transmission No
Yes
Sulfur granules
Yes (weakly acid-fast(
Acid-Fastness
Nocardiosis (abscess in brain & kidneys in immunodeficient patients – Pneumonia)
Actinomycosis (abscess with draining sinuses) Cervicofacial, Thorasic, Abd, Pelvic
Disease
Sulfonamides
Penicillin
Treatment