Submitted to: Journal of Food: Microbiology, Safety, and Hygiene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2018
Publication Date: 2/12/2018
Citation: Hinton Jr, A., Cox Jr, N.A. 2018. Selective medium for aerobic incubation of Campylobacter. Journal of Food: Microbiology, Safety, and Hygiene. 3(1):1-6.
Interpretive Summary: Studies were conducted on the preparation of a new medium that could be used in the aerobic isolation of Campylobacter from samples that also contained other bacteria. Three antibiotic mixtures (Bolton, Cefex, or Skirrow) were tested as supplements that could be added to the medium to allow the growth of Campylobacter while inhibiting the growth of other bacteria. First, the ability of cultures of Campylobacter to grow in non-supplemented media and in media supplemented with the antibiotic mixtures was determined. Then, the ability of other bacteria normally found in poultry samples to grow in the non-supplemented and supplemented media was determined. Finally, mixed bacterial cultures containing Campylobacter and other bacteria were prepared, and the ability of the non-supplemented media and supplemented media to allow Campylobacter bacteria to grow while inhibiting the growth of other bacteria was determined. Results of these experiments indicated that there was growth of Campylobacter when it was the only bacterium added to non-supplemented media and media supplemented with either Bolton, Cefex, or Skirrow antibiotic mixtures. However, while the other bacteria could grow in the non-supplemented media, the growth of these bacteria was inhibited in the supplemented media. It was also determined that when Campylobacter was grown in cultures containing other bacteria, Campylobacter could outgrow the other bacteria in the media supplemented with the Bolton antibiotics, but not in the non-supplemented medium. These experiments show that supplementing the new medium with Bolton’s antibiotic produces a selective medium that could be used using with aerobic incubation to isolate Campylobacter from samples containing other bacteria.
Technical Abstract: Studies were conducted on the formulation of a selective medium that could be used to isolate Campylobacter from mixed bacterial cultures using aerobic incubation. A non-selective, basal broth medium was prepared and supplemented with Bolton, Cefex, or Skirrow antibiotic mixtures. The ability of pure cultures of Campylobacter coli, Campylobacter fetus, Campylobacter jejuni, and Campylobacter lari to grow in basal broth and basal broth supplemented with each one of the antibiotic mixtures after aerobic incubation for 24 and 48 h at 37oC was determined. Also, the ability of pure cultures of Escherichia coli, Enterococcus faecalis, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Kentucky, and Staphylococcus aureus to grow in basal and supplemented broth medium was determined. Additionally, the recovery of bacteria from mixed cultures containing one Campylobacter isolate with the other 6 non-Campylobacter isolates after aerobic incubation for 48 h at 37oC in basal broth and broth supplemented with the Bolton antibiotic mixture was examined. Results indicated that there was significant (p < 0.05) growth of most Campylobacter isolates in basal broth and in broth supplemented with Bolton, Cefex, or Skirrow antibiotic mixtures after 24 or 48 h of aerobic incubation. Although, there was significant growth non-Campylobacter isolates in basal broth, growth of most these bacteria was inhibited in media supplemented with antibiotic mixtures. Also, Campylobacter growth was generally significantly less than other bacteria in mixed bacterial cultures grown in basal broth for 48 h at 37oC, but significantly more of most Campylobacter isolates were recovered from mixed bacterial cultures grown in media supplemented with the Bolton antibiotic mixture. Findings indicate that basal medium containing this supplement can serve as a selective medium that may be utilized with aerobic incubation to isolate Campylobacter from samples containing other bacteria.