1. Quantitative Bacterial Cultures: Using the method shown in Figure 2, quantitative cultures are performed on a portion of fluid that has been vortexed to assure optimal mixing of contents. No attempt is made to lyse cells to release intracellular organisms, although evaluation of its usefulness would be of interest. antibiotic levaquin
2. Concentration by Centrifugation: The remaining fluid is centrifuged to concentrate host cells and organisms for additional studies. Although the optimal relative centrifugal force (ref) and time for use with BAL fluid has not been determined, the procedure we use (1,800 Xg for 15 to 20 minutes) has been shown to be adequate for concentrating bacteria in CSF* and near the parameters considered adequate for mycobacteria in clinical specimens. In addition, this ref is readily attainable by centrifuges used in most laboratory settings.
3. Cytocentrifugation to Prepare Smears: Cytocentrifugation (Cy-tospin 2 Shandon Inc, Pittsburgh, PA) involves low-speed centrifugation of cells in suspension onto a microscopic slide with simultaneous absorption of fluid onto a filter pad. This process results in a discrete, 6 mm in diameter, monolayer of microorganisms and host cells with well-preserved morphologic features. A variety of stains, including an immunochemical one, may be used for rapid evaluation of host cells, assessment of inflammatory response, and detection of organisms (Fig 1).
4. Specialized Culture Procedures: A variety of selective media and specialized procedures may be used to detect distinct organism groups or genera (eg, Mycobacterium, Legionella, Mycoplasma, and Chlamydia).
5. Optional Tests: In general, sufficient material is available for performing additional tests, if necessary, including immunoassays, hybridization assays, or additional cultures (eg, viral).
Figure 2. Quantitative bacterial cultures.
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