培训课件--呼吸道标本的处理.ppt

* Slide 3. Staphylococcus aureusNumerous gram-positive cocci, round and large, are visible as single organisms, pairs, and grape-like clusters. The clusters strongly suggest that the organisms are staphylococci. The red strands of mucus粘液 in the background are common in good sputum specimens. * Slide 4. Nocardia asteroidesNocardia asteroides星状的are branching, beaded串珠状的, gram-positive bacilli. Actinomyces放线菌属look the same, and Streptomyces链霉菌属species are also long, branching gram-positive rods, but usually are not beaded. * Slide 5. Nocardia asteroidesWhen stained with a modified acid-fast technique, as this specimen is, most Nocardia are acid fast, but Actinomyces and Streptomyces species are not. The presence of branching, red rods on the blue background confirms that the organism is acid fast and thus most likely Nocardia. * Some fungi, particularly yeasts such as Candida and Cryptococcus species隐球菌属, are readily visible with Gram stain; others, such as Aspergillus曲霉and other molds, stain poorly but are sometimes detectable. Many species not visible with Gram stain are visible with other techniques, such as potassium hydroxide氢氧化钾or preparations made with nonimmunologic stains such as calcofluor white. Slide 1. Candida albicansThis low power (100x) view demonstrates gram-positive rounded structures (yeasts), many with pseudohyphae假菌丝(branches without septa). Yeasts, such as Candida albicans, are much larger than bacteria. Slide 2. Candida albicansThis view through an oil-immersion lens (1,000x) shows the large size of Candida albicans. Candida species seldom cause pulmonary infections, even in immunocompromised hosts. Therefore, if yeasts are found in sputum, contamination of the specimen by organisms from the upper respiratory tract should be suspected, especially if the patient has mucosal粘膜的candidiasis (thrush真菌性口炎) or has recently received an antimicrobial agent that allowed overgrowth of yeasts in the oropharynx口咽的. In specimens from such patien