Campylobacter Preston Broth Base ISO

The thermotolerant campylobacters have acquired a great importance in public health, especially as agents of human diarrheal disease. The most frequent thermotolerant species relevant to human health are Campylobacter jejuni and Campylobacter coli.

Enzymatic digest of animal tissue and casein and peptone provide nitrogen, vitamins, minerals and amino acids essential for growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Polymyxin B is active only against Gram-negative bacteria and Proteus species are sometimes resistant. Trimethoprim usually inhibits Proteus species and other Gram-negative bacteria. Rifampicin is also active against Gram-negative organisms. Amphotericin B suppresses yeasts and fungi growth. The increment of temperature has shown an increase in selectivity.

Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.

Preparation

Suspend 25 grams of the medium in 940 mL of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Sterilize in autoclave at 121 °C for 15 minutes. Cool to 47 °C and aseptically add two vials of Preston Campylobacter Supplement (LC-6081), together with a previously prepared solution sterilized by filtration containing 0.25 g sodium pyruvate, 0.25 g sodium metabisulfite, and 0.25 g iron(II) sulfate hydrate, dissolved in 5 mL of water. Then add 50 mL of sterile lysed horse blood. Homogenize gently and dispense into appropriate containers.

According to ISO 10272

For the detection and enumeration of Campylobacter spp. for samples with low numbers of campylobacters and high level of background microflora according to ISO 10272:

1. Add the test portion to the liquid enrichment medium Preston Broth. In general, for preparing the initial suspension, combine a quantity of 10 g or 10 mL of the test portion with 90 mL of the Preston Broth.
2. Incubate in a microaerobic atmosphere at 41.5 °C for 24 ± 2 h.
3. From the enrichment culture obtained, inoculate the selective medium CCDA Agar (LC-1129).
4. Incubate the selective solid medium at 41.5 °C in a microaerobic atmosphere for 44 h to detect the presence of suspect Campylobacter colonies.
5. Examine the suspect Campylobacter colonies for morphology and motility using a microscope, subculture on a non-selective blood agar, and then confirm by detection of oxidase activity and an aerobic growth test at 25 °C.

• ISO 10272:2017 Microbiology of the food chain - Horizontal method for the detection and enumeration of Campylobacter spp. Part 1: Detection method.