医学微生物学资料：Actinomyces Nocardia

1、1Actinomyces & NocardiaActinomycetaceae Mycobacterium 分枝杆菌属Corynebacterium 棒状杆菌属Norcardia 诺卡氏菌属Actinomyces 放线菌属Streptomyces 链霉菌属Rhodococcus 红球菌属3Features of ActinomycetesGenus Morphology Acid-fastnessGrowth Source Disease Actinomyces Branching bacillinoneanaerobicOral, intestinal endogenous floraChr

2、onic cellulitis, draining sinusesNocardia Branching bacilli weakaerobicsoilPneumonia, skin pustules, brain abscessRhodococcus Cocci to bacilliVariable(weak)aerobicSoil, horsespneumoniaStreptomyces Branching bacilliNone Aerobic Soil Extremely rare?4ActinomycesSlow-growing, anaerobic; branching Gram-p

3、ositive rodsIn pus tissues, sulfur granule is the most characteristic form(0.3mm)Most infections due to A israelii Bacteriology5Actinomycosis Flora throughout gastrointestinal tractEndogenous infection.Infection often involve mechanical disruption of the mucosa如拔牙Sinus tract contain pus and sulfur g

4、ranulesNo evidence of immunity.6andActinomycosis Chronic cellulitis, draining sinusesNocardiosis Pneumonia, skin pustules, brain abscess7Actinomycosis : ManifestationsActinomycosis exists in several forms Cervicofacial forms are most commonly seen, often linked to dental hygiene Thoracic and abdomin

5、al actinomycosis are rare Chronic endometritis Surgery, trauma, and intrauterine devices provide opportunity.Cervicofacial Actinomycosis8Actinomycosis : Diagnosis Sinus drainage/pus contains few Actinomyces Drainage is often contaminated with other species Gram stains show branching rods Anaerobic c

6、ulture is required9Actinomycosis : Treatment Penicillin G Penicillin may have to be used empiricallyHigh dose, prolonged therapy Ampicillin , doxycycline, erythromycin, and clindamycin. 10Nocardia Bacteriology Beaded, branching Gram-positive rods ,weakly acid-fast Grow on common media in 2 to 3 days

7、 In contrast to Actinomyces, Nocardia species are strict aerobesAerial hyphae of NocardiaOrange colonies of Nocardia12Nocardiosis : Epidemiology Ubiquitous : primary source is soil ; Available in respiratory tract of healthy personsTransmitted by : Inhalation (pulmonary form ), Injection through tra

8、uma (cutaneous form )No case-to-case transmissionInfection in the immunocompromised is increased13Nocardiosis : Pathogenesis Able to survive in phagocytesPulmonary infection : N asteroids CNS dissemination: produces abscesses Minor trauma increases Cutaneous infectionsSkin infections is usually rela

9、ted to N brasiliensis species 14Nocardiosis :Immunity Cell-mediated immunity : are dominant Macrophages:enhance capacity to kill Nocardia Patients with impaired cell-mediated immunity at higher risk for Nocardiosis 15Nocardiosis : Manifestations Bronchopneumonia : cough,dyspnea, and fever Brain absc

10、ess Cutaneous syndrome: typically involves a pustule, fever, and tender lymphadenitis in the regional lymph nodes.16Nocardiosis : Diagnosis Gram stain is usually positiveOrganisms are present in greater numbers and distributed more evenly Weak acid fastness is characteristic: diagnostic for N astero

11、ids or N brasiliensis Blood agar is sufficient for culture 17Nocardiosis : Treatment Sulfonamides Sulfonamides combined with trimethoprim Technique difficulties in sensitivity testing Resistant to penicillin, but some of the newer beta-lactams effective Antituberculous agents and antifungal agents such as amphotericin B have no activity against Nocardia.18放线菌主要有放线菌属和诺卡氏菌属。放线菌属:人体正常菌群，与牙周病、龋齿等口腔疾病有关。侵入软组织可引起放线菌病。放线菌引起的感染菌为内