Nocardia, Actinomyces, Propionibacterium Aerobic Gram-Positive Bacilli Form filaments (Aerobe, Anaerobe)

Order: Actinomycetales Fungus-like characteristics, branching (like mycelium) Filaments; pleomorphic, diphtheroid, coccoid cells Bacteria (prokaryote) not fungal (eukaryote) –Prokaryote cell wall, internal structures –Antibiotic susceptibility All slow growing Considered higher prokaryotes Aerobic –Nocardia - cutaneous, pulmonary, CNS, opportunistic infection Anaerobic –Actinomyces - actinomycosis –Propionibacterium - acne, opportunistic infection

Nocardia Found worldwide soil, vegetation G(+), may be weak; branching filaments, fragment bacillary, coccoid forms Partially acid fast (use weak acid decolorize), due to mycolic acid in cell wall Wide infection range – colonize, mycetoma, systemic, pulmonary, opportunist

Nocardia: Lab culture Slow growth most lab media; require up to 1 week culture Specimens inoculated enriched media –Brain heart infusion agar –7H10, Lowenstein-Jensen (designed for Mycobacterium culture) Colonies - orange, dry, crumbly, adherent Better isolation on enriched selective media such as BCYE + antibiotics Aerial hyphae on colony surface

Nocardia: Mycetoma (Cutaneous) Mainly caused by N. brasiliensis; common in tropical, semi-tropical areas, rare in USA MO enters body through breaks in skin, often splinters, thorns of hands and feet Localized infection involving skin, cutaneous, subcutaneous tissue Three features seen: –Swelling, pus –Draining sinus tracts –Granules (yellow, “sulfur”) in pus

Nocardia: Nocardiosis (Inhalation) Mainly caused by Nocardia asteroides Usually disease of compromised host Localized, disseminated disease following inhalation of MO Resembles TB – bronchopneumonic, acute or relapsing; abscesses coalesce, extensive tissue damage May disseminate, predilection for brain meninges High mortality

Nocardia: Treatment and Prevention Antibiotic therapy - 6 weeks or more to prevent dissemination of infection Mycetoma –Aminoglycoside –Proper wound care and drainage –Surgical intervention Nocardiosis –Sulfonamides, SXT –Combination antibiotics for severe, progressive disease MO ubiquitous in environment, impossible to avoid

Actinomyces “ray” “fungus” G(+) pleomorphic, diphtheroid bacilli; filamentous Not acid fast Facultative anaerobe, strict anaerobe Grow slowly on anaerobic CBA, PEA –Rough, granular colonies, resemble molars Lab ID: –Gas liquid chromatography (GLC) of metabolic by-products –Specific fluorescent antibody staining assay Most commonly isolated – Actinomyces israelii

Actinomyces: Actinomycosis Normal flora in humans, animals Colonize - URT, GI, female GU tract Endogeneous infection – NF invade host when mucosal disrupted (trauma, surgery, ingestion, foreign bodies i.e. intrauterine device) Cervicofacial infection - “lumpy jaw” –Following tooth extraction, dental surgery –May invade bone –Rare today due to prophylactic antibiotics Thoracic, abdominal infection Meningitis, endocarditis, genital infection Slow developing, chronic infection

Actinomycosis Infection characterized by draining sinuses Characteristic granules –Bacteria colonies; dense rosettes of club-shaped filaments –Radial arrangement Treatment –Penicillin –Surgical removal diseased tissue

Propionibacterium: Genera “propionic acid” Normal flora of skin, oropharynx, female GU tract G(+) small bacilli, pleomorphic, diphtheroids Most common isolates –P. acnes – acne, oportunistic infection –P. propionicus – oral abscess

Propionibacterium: Lab Culture Grow well on CBA –Tiny translucent, opaque, white to gray colonies Growth may be slow Anaerobic Occasional strains grow in CO 2 (aerotolerant)

Propionibacterium: Infection and Disease Skin normal flora Implicated in acne –Adolescence more sebum produced –P. acnes metabolizes sebum to fatty acids –Contribute to inflammatory response in acne Opportunistic infection – prosthetic device (heart valves, joints), IV lines (catheter, CSF shunt)

Propionibacterium: Treatment and Prevention Skin cleansing not effective, lesion develops in sebaceous follicle Topical benzoyl peroxide and antibiotics Accutane –Inhibits sebum formation –Used only in severe case of acne because of side effects Effectively treated by erythromycin, clindamycin

Class Assignment Textbook Reading –Chapter 16 Aerobic Gram-Positive Bacilli Aerobic Actinomycetes - Nocardia –Chapter 22 Anaerobes of Clinical Significance Actinomyces Propionibacterium Key Terms Learning Assessment Questions

Lecture Exam II Tue., Feb. 28, 2012 Vibrio thru New Molecular Methods Lecture, Reading, Key Terms, Learning Assessment Questions Case Study 4, 5, 6 (Pseudomonas, Francisella, Bacillus) Exam Format –Multiple Choice –Terms –True/False Statements –Short Essay Review, Review, Review!

Case Study Reports (Revised Due Date) March 1 - CS #7 Mycobacterium March 6 – CS #8 Clostridium March 8 – CS #9 Chlamydia March 13 – CS #10 Legionella