Use of colistin and sorbitol for better isolation ofSerratia marcescensin clinical samples

Abstract

SUMMARYA comparison was made of different culture media and procedures for detection ofSerratia marcescensfrom faecal, pharyngeal and ocular swabs collected from 213 neonates. MacConkey agar and MacConkey agar with sorbitol (1%) and/or colistin (200 i.u./ml) were used both for primary isolation and after enrichment using Mossel Enterobacteriaceae broth with colistin (200 i.u./ml). The use of MacConkey agar supplemented with colistin for primary isolation improved considerably the isolation rate ofS. marcescensfrom faecal swabs but not from pharyngeal swabs; the number of ocular isolations were insufficient to demonstrate differences between procedures. Moreover the enrichment procedures consistently increased the number ofS. marcescensisolates especially from pharyngeal and ocular swabs. Use of sorbitol made detection ofS'. marcescensfrom clinical specimens easier and time– and cost–efficient.