The ability of campylobacter media supplements to neutralize photochemically induced toxicity and hydrogen peroxide

Nutrient agar plates stored in light and air for 48 h became inhibitory for Campylobacter jejuni, C. coli and nalidixic acid-resistant, thermophilic campylobacter (NARTC) strains. All five campylobacter test strains showed greater than 5 log reduction in counts on media which had been stored in light and air. Media stored in the dark and/or in a reduced atmosphere did not become inhibitory and supported the growth of campylobacters. Ferrous sulphate, sodium pyruvate, blood, charcoal or sodium metabisulphite, compounds frequently used as supplements in campylobacter media, were added to nutrient agar prior to storage of media in light and air. All additives except sodium metabisulphite prevented the accumulation of photochemically generated toxic oxygen derivatives and allowed growth of test strains. In qualitative tests to determine the ability of supplements to neutralize hydrogen peroxide, blood was the most active, charcoal and sodium pyruvate slightly less active and ferrous sulphate and sodium metabisulphite the least active. The results of this study confirm that supplements in campylobacter media act as quenching or detoxifying agents and not as enrichment factors.