EFFECT OF SUPPLEMENTS ON CAMPYLOBACTER GROWTH IN ENRICHMENT MEDIA¹

Abstract

Supplementation of Niroomand and Fung broth (NFB) and Hunt broth (HB) with Oxyrase®, sheep blood, hemin or yeast extract for recovery of Campylobacter was evaluated. Five strains of C. jejuni and one strain of C. coli were cultured in HB with or without Oxyrase®, NFB with or without Oxyrase®, NFB without hemin, and NFB plus yeast extract without hemin. The HB without Oxyrase® was evacuated and flushed three times with mixed gas (5% O2, 10% CO2, and 85% N2) prior to incubation. The effect of blood in HB supplemented with Oxyrase® on the growth of Campylobacter was also examined. Hunt broth showed significantly better performance than NFB (p<0.05). Supplementation of 0.2% hemin and 0.6% yeast extract stimulated growth by up to 2 log CFU/mL depending on strains. Addition of 7% lysed blood enhanced growth of C. jejuni, and differences were significant at 6 h and 24 h of incubation. At 20 h of incubation, broth containing 0.6 units/mL of Oxyrase® yielded Campylobacter counts of 8.6 to 10.9 log CFU/mL, and the broth flushed with mixed gas provided counts of 9.4 to 11.0 log CFU/mL. No statistical difference (p>0.05) was found between the Oxyrase® method and gas replacement method at incubation times of 12h, 20h, 28h, and 36h for all strains tested. Dissolved oxygen levels of all enrichment media were less than 1.5 mg/L. Using Oxyrase® supplemented HB without the cumbersome gassing step provides a simple and time‐saving procedure for culturing Campylobacter jejuni and C. coli.