A method for measuring cell concentration and identity based on flow cytometry (FCM) and fluorescent marking is developed and subsequently compared with traditional plating based methods, with regards to performance, economy and ergonomy. The emphasis is on competitive growth of bacteria under antibiotic stress, but the technique could be used in any situation requiring fast, high throughput counting and identification of cellular populations. The method needs further development, but shows potential as a parallelizable and fast alternative to plating.