医学微生物学实验课件：4粪便分离.pdf

实验四粪便标本分离-II 肥达、梅毒反应素检测 内容： 1、视频：厌氧菌感染 2 、讨论：流感嗜血杆菌，白喉棒状杆菌 示教镜：白喉棒状杆菌亚碲酸钾平板菌 落、异染颗粒 3 、粪便标本划线接种结果观察 4 、操作：粪便标本培养接种肉汤培养基 5 、操作：粪便标本培养革兰染色 嗜血杆菌属Haemophilus - G small, pleomorphic, fastidious H. influenzae • heme synthesis deficient X factor dependent • NAD synthesis deficient V factor dependent • Satellite phenomenon • Capsulated (6 serotypes, Hia-Hif) strains are usually invasive pathogens, esp. Hib, and cause meningitis and epiglottitis 会厌炎 in 3m-5y old children • Uncapsulated (untypable, UTHI) strains are common commensals in upper respiratory tract, causing secondary pneumonia and other non- invasive diseases (otitis media, sinusitis, conjunctivitis, exacerbation of COPD etc.) • -lactamase encoded by transmissible plasmid in 25% Hib; 3rd gen. cef i.v. H. ducreyi • X factor-dependent, V factor-independent • causes STD chancroid (soft chancre, 软下疳); treated with oral azithromycin; no lasting immunity 流感嗜血杆菌卫星现象 棒状杆菌属 Corynebacterium G+ (Actinomycetes放线菌门) club-shaped rods C. diphtheriae • Black colonies on agar containing potassium tellurite 亚碲酸钾(reduction) • Metachromatic granules in aniline 苯胺staining • Four biotypes: gravis, mitis, intermedius, belfanti • Toxigenic strains carry lysogenic phage encoding diphtheria exotoxin (Dt), probably expressed on cell lysis • Dt is a typical A-B toxin and causes ADP-ribosylation of EF-2 • Pseudomembrane: Dt is absorbed through mucosa, destroys epithelium and causes local inflammation. Necrotic epithelium is embedded by fibrin and blood cells to form a grayish pseudomembrane over tonsils, pharynx or larynx. • Dt released by C. d. in pseudomembrane enters blood and damages distant tissues (heart, liver, kidney, etc) without bacteremia • Immediate administration of anti-toxin upon presumptive diagnosis