Growth Responses of Coliform Bacteria to Recombinant Bovine Cytokines

Abstract

Growth responses of 10 coliform isolates to recombinant bovine cytokines were measured in vitro. Six Escherichia coli and four Klebsiella pneumoniae isolates obtained from bovine MI were tested for growth responses to recombinant bovine interleukin-β, interleukin-2, and interferon-γ. Cytokines were tested at 104, 103, 102, and 10 U/ml of media. Media used were a synthetic tissue culture medium, a chemically defined synthetic bacterial growth medium, and UHT sterilized milk. Bacterial counts in the synthetic tissue culture medium and UHT milk increased slightly as concentration of interferon-γ in the media increased. Recombinant bovine interferon-γ increased bacterial populations during the log growth phase but did not affect the number of bacteria in stationary growth phase. Bacterial growth responses were not related to either interleukin-2 or interleukin-1β concentrations in any of the three media. Bacterial growth responses to cytokines were not related to differences in either serum susceptibility, growth of isolates in dry cow secretion, duration of IMI from which isolates were obtained, or bacterial species. © 1993, American Dairy Science Association. All rights reserved.