Bordetellae and charcoal horse blood agar: inactivation of antibiotics in agar during prolonged incubation for susceptibility testing.
We examined the degree of inactivation of 22 antibiotics caused by prolonged incubation at 36 degrees C of agar plates during agar dilution susceptibility testing of Bordetellae. Fresh antibiotic-containing plates of charcoal horse blood agar and plates which had been held at 36 degrees C for 2 or 3 days prior to inoculation were inoculated with strains of Bordetella pertussis and Bordetella parapertussis and incubated for 2 days. Then the MICs were compared. Most antibiotics showed a loss of activity of up to four dilution steps after prolonged incubation. Further studies with other slow-growing organisms and other complex media are needed.
D000362:Agar; D000818:Animals; D001769:Blood; D001884:Bordetella / Q000187:drug effects*; D001886:Bordetella pertussis / Q000187:drug effects*; D004355:Drug Stability; D006736:Horses; D008826:Microbial Sensitivity Tests / Q000379:methods*; D013997:Time Factors
D000362:Agar