A preliminary study was performed for the enumeration of microorganism contamination of the macrolide antibiotic, Spiramycin, using epifluorescence with the ChemScan solid phase cytometer. The artificial spiking of Spiramycin powder antibiotic with pure culture of four microorganisms led to complete recovery of the tested organisms, whatever their sensitivity to the bacteriostatic activity of the drug. With the conventional plate method run in parallel, complete recovery was only obtained for Spiramycin resistant organisms. The spiked microorganisms that were sensitive to the antibiotic remained inhibited or stressed by the action of the Spiramycin and did not grow on the plate.