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Rapid sulfonamide disc sensitivity test for meningococci
Abstract:
Minimal inhibitory concentrations (MIC) of 90 strains of Neisseria meningitidis were determined by a plate dilution technique that employed twofold changes in concentrations of sulfadiazine. The geometric mean of three MIC determinations on each strain was correlated with inhibition zones produced by a 300-mug sulfathiazole disc. The linear relationship between the logarithm of the geometric mean MIC values and the zone diameters was highly significant. Strains were separated into sensitive and resistant populations by both test procedures. Quantitative criteria for interpreting the sensitivity of a strain by the disc test were established.
Insights
This study correlated sulfadiazine minimal inhibitory concentrations (MIC) with sulfathiazole disc inhibition zones for Neisseria meningitidis. A significant linear relationship was found, enabling the classification of bacterial strains into sensitive and resistant groups.
Area of Science:
- Microbiology
- Antimicrobial Susceptibility Testing
Background:
- Neisseria meningitidis is a significant human pathogen.
- Accurate susceptibility testing is crucial for effective treatment.
Purpose of the Study:
- To correlate minimal inhibitory concentrations (MIC) of sulfadiazine with sulfathiazole disc inhibition zones for Neisseria meningitidis.
- To establish quantitative criteria for interpreting disc diffusion test results.
Main Methods:
- Determined MIC of sulfadiazine for 90 Neisseria meningitidis strains using a plate dilution technique.
- Correlated geometric mean MIC values with inhibition zone diameters from sulfathiazole disc tests.
- Analyzed the linear relationship between logarithm of MIC values and zone diameters.
Main Results:
- A highly significant linear relationship was observed between logarithm of geometric mean MIC values and zone diameters.
- Both MIC determination and disc diffusion tests effectively separated strains into sensitive and resistant populations.
- Quantitative criteria for disc test interpretation were successfully established.
Conclusions:
- Sulfathiazole disc diffusion test is a reliable method for determining sulfadiazine susceptibility in Neisseria meningitidis.
- Established criteria facilitate accurate interpretation of disc diffusion tests for clinical and epidemiological purposes.