Evaluation of disc diffusion susceptibility testing performed from a four-hour subculture of positive blood culture bottles.
Disc diffusion susceptibility tests were performed on standardized broth suspensions inoculated from a four-hour subculture of a positive blood culture bottle as well as from an agar plate subculture of the same positive blood culture bottle. The zone sizes and interpretative results of both methods were compared. Of 101 isolates tested, only one organism exhibited a very major difference between the two methods (one Staphylococcus epidermidis was interpreted as susceptible to methicillin by the four-hour subculture method and resistant by the agar plate subculture method). Thirteen other isolates showed minor changes from susceptible or resistant to intermediate or from intermediate to either susceptible or resistant with only one antibiotic each. The data indicates that disc diffusion susceptibilities may be performed easily and accurately from a four-hour subculture of positive blood culture bottles.
D005069:Evaluation Studies as Topic; D008826:Microbial Sensitivity Tests / Q000379:methods; D013997:Time Factors