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

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.

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 Habitat is the human respiratory tract. Transmission : Respiratory droplets.

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.

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

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

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

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

Actinomycetes

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

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

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

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.

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

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

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.

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.

ACTINOMYCETES Nocardia asteroides

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

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

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

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

Nocardia asteroides Diseases Diseases: Abscesses in: Lung Brain Kidney

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.

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

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