Interpreting streptomycin susceptibility test results for Salmonella enterica serovar Typhimurium

Resistance or susceptibility of Salmonella enterica to streptomycin is widely used as an epidemiological marker. However, there is no clear consensus on the interpretation of streptomycin susceptibility test results. Comparison of results obtained with the Clinical and Laboratory Standards Institute (CLSI) disk diffusion method, the minimum inhibitory concentration (MIC) determined by Etest and streptomycin resistance genotype for 90 isolates of S. enterica serovar Typhimurium suggests that appropriate interpretive criteria for MIC results are susceptible at <= 8 mg/L and resistant at >= 16 mg/L. For CLSI disk diffusion, we propose susceptible at a zone diameter >= 13 mm and resistant at <= 10 mm. (c) 2006 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.