CAMPYLOBACTER ENRICHMENT BROTH BASE (PRESTON ENRICHMENT BROTH BASE)

Description

Balton and Robertson described this as a selective medium for the cultivation of Campylobacter species. It is recommended by APHA for enrichment of thermotolerant Campylobacter species from foods. Preston Enrichment Broth has a rich basal medium to aid resuscitation of sublethally damaged Campylobacter. Preliminary incubation of the medium complete with antibiotics for 4 hours at 37?C was recommended to aid resuscitation of injured organisms followed by 42?C for 18-48 hours. Preston Selective Supplement contains antibacterial and antifungal agents. Polymyxin B is active only against gram-negative bacteria and Proteus species are sometimes resistant. Trimethoprim usually inhibits Proteus species as well as other gram-negative bacteria. Rifampicin is also active against gram-negative organisms. Cycloheximide acts as antifungal agent. Direct plating without enrichment is adequate for fresh faecal samples, fecal contents or intestinal specimens as high numbers of the organisms may be anticipated. For food samples enrichment is required. Humphrey suggested that pre-enrichment at 37?C should be continued for 4 hours and that addition of all antibiotics should be delayed until the 4 hours, pre- enrichment had been completed. Enrichment medium with rifampicin was recommended in parallel with similar plating medium. The Campylobacter species grow well in microaerobic conditions i.e. in 5% O2 at 42?C in about 48 hours. Addition of about 4 drops of glycerol to a filter paper kept within the jar/container will hamper confluent and swarming growth of Campylobacter.