New role of antibody in bacterial isolation.

To eliminate the interference caused by Pseudomonas aeruginosa in the isolation of Salmonella, a rabbit polyclonal antibody against P. aeruginosa was prepared by inoculating four New Zealand rabbits with the pathogen. The antiserum was purified using saturated ammonium sulfate and added into Rappaport-Vassiliadis medium with soya (RVS) broth and Muller-Kauffmann tetrathionate novobiocin broth (MKTTn broth) to evaluate whether it could inhibit the growth of P. aeruginosa. Observations by scanning electron microscopy demonstrated that P. aeruginosa was attacked and destroyed by the antibody when incubated for 10 min at 37 degrees C. The activity of the antibody was also effective against 11 other strains of P. aeruginosa. Twenty-six strains of Salmonella were mixed with P. aeruginosa in RVS and MKTTn broth at 37 degrees C for 12 h, respectively, and the cultures were plated on Salmonella chromogenic medium (SCM; Oxoid, Basingstoke, UK). Only Salmonella grew on SCM; five colonies were randomly selected for identification by VITEK 2 (bioMerieux, Lyon, France). Additionally, when mixed with two strains of Enterobacter cloacae (ATCC 700323 and YG001), the prepared antibody did not affect the growth of E. cloacae. The results demonstrated that the microbicidal activity of the antibody did not affect the tested Salmonella sp. or E. cloacae strains. Therefore, the antibody generated could be used to increase the accuracy of Salmonella isolation.