Transcript Mycoplasma pneumoniae - جامعة الملك عبدالعزيز

Mycoplasmas and Actinomycetes
Presented by
‫ آصف احمد محمد جي مان فطاني‬.‫د‬
)‫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
MYCOPLASMAS
Characteristics
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Lacking cell wall
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Enclosed in a plasma membrane
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Lipid bilayer membrane containing sterols
Smallest free-living organisms
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Resistant to antibacterials that inhibit cell wall synthesis
Gram’s stain : Not useful
Pleomorphic
Cannot be classified as either cocci or bacilli
Pass through bacteriologic filters
Can be cultured in vitro.
MYCOPLASMAS
Mycoplasma pneumoniae → Atypical Pneumonia
Mycoplasma hominis
→ STI: Non-gonococcal
Urethritis, Cervicitis, PID
Ureaplasma urealyticum
→ STI: Non-gonococcal
Urethritis, Cervicitis, PID
Mycoplasma pneumoniae )Eaton’s reagent(
Habitat and Transmission
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Habitat is the human respiratory tract.
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Transmission : Respiratory droplets.
Mycoplasma pneumoniae
Pathogenesis
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P1 adhesion protein
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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
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Produces hydrogen peroxide : may damage the
respiratory tract.
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No exotoxins produced.
No endotoxin because there is no cell wall.
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Mycoplasma pneumoniae
Diseases
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Atypical pneumonia :
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Clinical Features: Fever – Dry cough “or scantily
productive cough”
Walking pneumonia
Complications: Mild hemolytic anaemia
Upper Respiratory Diseases :
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Otitis Media
Pharyngitis
Tracheobronchitis
Mycoplasma pneumoniae
Laboratory Diagnosis
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Specimens: but scanty sputum
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Gram stain : not useful.
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Culture: on special bacteriologic media. Takes at least 10 days to grow (too
long to be clinically useful).
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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
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Note : Diagnosis relies on clinical findings
Mycoplasma pneumoniae
Treatment
Erythromycin or …
 Tetracycline.
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Prevention
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No vaccine or drug is available
Genital Mycoplasmas
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Mycoplasma hominis
→
STD: Non-gonococcal
Urethritis, Cervicitis, PID
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Ureaplasma urealyticum →
STD: Non-gonococcal
Urethritis, Cervicitis, PID
Actinomycetes
Actinomycetes
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Gram positive bacteria
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Filamentous branching bacilli
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Superficially resemble fungi on morphologic grounds
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They are prokaryotes
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Has bacterial size
Actinomycetes
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Few are pathogenic to human, the most
important are :
Actinomyces israelii
 Nocardia astroides
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ACTINOMYCETES
Actinomyces israelii
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Gram-positive filamentous branching bacilli
Anaerobic
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Grows slowly
Actinomyces israelii
Habitat and Transmission
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Habitat : Found as scanty normal commensal in the:
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Mouth, especially anaerobic crevices around the teeth
Colon
Vagina
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Disease begins when these normal flora enter adjacent
sterile tissue e.g, by trauma, surgery
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Transmission into tissues occurs during :
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Dental extraction - Poor dental hygiene
Trauma (mouth – uterus)
Organism also aspirated into lungs, causing thoracic actinomycosis.
Actinomyces israelii
Pathogenesis
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Infections occur in both :
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Normal hosts
Immunocompromised patients
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No toxins or virulence factors known.
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Organism forms sinus tracts that open onto skin and contain
yellow “sulfur granules”
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Sulfur granules : are made up of large masses of
organisms microcolonies of filamentous bacteria
Actinomyces israelii
Disease
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Actinomycosis (abscesses with draining sinus tracts)
Chronic suppurative abscess
The lesion (Mycetoma) :
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Begins as a hard red swelling
Ddevelops slowly, becomes filled with pus
Draining with sinus formation
Sites:
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Oral-facial abscesses (> 50% of cases)
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Abdominal infections:
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Abscess. Many after appendicitis
Uterine infection :
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Often associated with trauma or dental extraction
Associated with intrauterine contraceptive devices
Chest infection
Invasive infections in immunocompromised patients
Actinomyces israelii
Laboratory Diagnosis
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Specimen: Pus
 Filaments may aggregate to form visible granules “Sulphur
granules” in pus: Yellowish particles
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Microscopy:
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Sulfur Granules : Gram-positive filamentous, branching rods
Culture:
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No sulphur
Anaerobic culture on blood agar plate (10 days)
Molar teeth colonies
No serologic tests.
Actinomyces israelii
Treatment
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Penicillin
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For up to 3-12 months
Tetracyclin or Clindamycin
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For penicillin-allergic patients
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Surgical drainage
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Prevention
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Good oral hygiene
Prophylactic antibiotics in association with GIT or oral
trauma or surgery
No vaccine is available.
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ACTINOMYCETES
Nocardia asteroides
Nocardia asteroides
Disease
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Nocardiosis (especially lung and brain abscesses).
Nocardia asteroides
Characteristics
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Gram positive filamentous, branching rods.
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Aerobic
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Acid-fast (weakly)
Nocardia asteroides
Habitat and Transmission
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Habitat is the soil.
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Transmission :
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Airborne particles, which are inhaled into the lungs
Implantation : by contamination of skin wounds
Nocardia asteroides
Pathogenesis
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Predisposing Factors:
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Immunosuppression
HIV
Cancer
No toxins or virulence factors known.
Nocardia asteroides
Diseases
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Diseases: Abscesses in:
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Lung
Brain
Kidney
Nocardia asteroides
Laboratory Diagnosis
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Specimen : Pus
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Microscopy :
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Culture :
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Gram-stained smear : Gram positive filamentous, branching rods
Ziehl-Neelsen stain (modified) : weakly AFB (branching)
Aerobic culture on blood agar plate.
No serologic tests.
Nocardia asteroides
Treatment
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Sulfonamides
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Long duration
Nocardia is resistant to penicillin
Prevention
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No vaccine is available.
Differences between Actinomyces israelii & Nocardia astroides
Actinomyces israelii
Nocardia astroides
Growth
Atmosphere
Anaerobic
Aerobic
Habitat
Mouth, Colon, Vagina
Soil
Transmission
Trauma (Tooth
Inhalation or implantation
extraction, Jaw fracture,
Intrauterine Contr. Dev.)
Sulfur granules
Yes
No
Acid-Fastness
No
Yes (weakly acid-fast(
Disease
Actinomycosis
(abscess with draining
sinuses) Cervicofacial,
Thorasic, Abd, Pelvic
Nocardiosis (abscess in
brain & kidneys in
immunodeficient patients
– Pneumonia)
Treatment
Penicillin
Sulfonamides