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Evaluation of Microbial Safety of Dairies using Bacterial Proteomic Profiling via MALDI Approach
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DIFFERENTIATION OF HEMOLYTIC STREPTOCOCCI OF HUMAN AND OF DAIRY ORIGIN BY METHYLENE BLUE TOLERANCE AND FINAL ACIDITY

R C Avery1

  • 1Department of Bacteriology and Immunology, School of Medicine, Vanderbilt University, Nashville, Tennessee.

The Journal of Experimental Medicine
|October 30, 2009
PubMed

Insights

This study classifies 138 hemolytic streptococci strains using dye-sensitiveness and pH. Findings differentiate human parasitic, bovine parasitic, and saprophytic strains based on their unique metabolic characteristics and methylene blue reduction.

Area of Science:

  • Microbiology
  • Bacteriology

Background:

  • Hemolytic streptococci are a diverse group of bacteria with varying host associations.
  • Understanding their metabolic differences is crucial for accurate classification and control.

Purpose of the Study:

  • To classify 138 strains of hemolytic streptococci.
  • To differentiate strains based on dye-sensitiveness and final hydrogen-ion concentration (pH).

Main Methods:

  • Grouping strains based on dye-sensitiveness (methylene blue reduction) and final pH of cultures.
  • Utilizing milk as a culture medium for testing methylene blue reduction.

Main Results:

  • Three distinct groups were identified: human parasitic, bovine parasitic, and saprophytic strains.
  • Human parasitic strains showed a final pH of 5.2-5.0 and did not reduce methylene blue.
  • Bovine and saprophytic strains exhibited a final pH of 4.5-4.2, with saprophytic strains reducing methylene blue.

Conclusions:

  • Dye-sensitiveness and final pH are reliable markers for differentiating hemolytic streptococci strains.
  • Methylene blue reduction capability correlates with strain type and has implications for its bactericidal effect.

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