A comparative study was performed with 176 cultures of Salmonella organisms on tetracyline, neomycin and colistin in order to find out the relationship between the results obtained from the Ericsson´s single disk method and the tube dilution method of antibiotic sensitivity tests which may be carried out in many hospital laboratories.
With tetracycline, thirty-three out of 163 cultures of Salmonella typhi were found to be either sensitive or moderate sensitive by means of the disk method and thirty one (ca 94%) out of the thirty three cultures showed less than 1. 0 ,ug of the Minimal Inhibitory Concentrations (MIC) in the tube-dilution tests, which mean that there were a quite good agreement between the two methods. With neomycin, a hundred and five out of 163 S.typhi were appeared to be either sensitive or moderate sensitive by means of Ericsson´s single disk method, among which 103 cultures showed less than 10. 0 ,e.g. MIC in the tube dilution method. And also there was a quite correlative patterns observed in the result of testing with 13 salmonella cultures other than S. typhi. With colistin, it was hard to observe any particular tendency in the distribution of plotting for 148 cultures showing less the 18 mm in the inhibiting zone diameters between MIC and disk sensitivity patterns except the fifteen, cultures out of 176 salmonella, which appeared to be sensitive in the single disk method and showed less than 1. 0 ug MIC in the tube dilution method.
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