Microanalysis of antimicrobial properties of human fluids

Host defense responses of animals and plants to pathogenic microbes are med iated in part by the release of antimicrobial substances into tissue fluids . Exploration of the antimicrobial properties of tissue fluids is often lim ited by their small quantity. We have developed assays of antimicrobial act ivity that require only 1 mu l of fluid. Using normal nasal secretions as a model mucosal Fluid we demonstrated that the kinetics of the 1 mu l colony -forming unit (CFU) assays were equivalent to the larger CFU assays. The ha ndling of viscous mucin-containing fluids was facilitated by pretreatment w ith N-acetylcysteine (NAC), a treatment that did nut alter the performance of the assay. This low-volume assay will facilitate studies of the antimicr obial properties of scarce biological fluids. (C) 2000 Elsevier Science B.V . All rights reserved.