Bacteriocin (marcescin) typing of clinically isolated Serratia marcescens

A study of bacteriocin (marcescin) typing was carried out by an agar cross streaking method (without any induction reagent) with 654 strains of Serratia marcescens recently isolated from clinical materials in Nagasaki University Hospital. In a complete checker board experiment with 80 strains on bacteriocin production and sensitivity, 43 strains (54%) were productive, 74 (93%) were sensitive and 4 (5%) were negative. Immunity was confirmed in all strains. Eight out of 80 strains of Serratia marcescens were selected as indicators in order to achieve the best differentiation of strains in bacteriocin typing, and 654 strains were classified into 30 types by bacteriocin production typing and into 49 types by bacteriocin sensitivity typing; the former showed more stable results than the latter in reproducibility. Bacteriocins produced by this method were considered to be high molecular, phage tail-like group A bacteriocins reported by Prinsloo (1966). Bacteriocin production typing was more useful for classification and subdivision of strains than serotyping (0-group).