Thermal Death Point of Streptococci

Abstract

Two hundred strains of hemolytic streptococci from septic sore throat, scarlet fever, erysipelas, etc., due to hemolytic streptococci and transmitted at times through milk, were tested as to thermal death points while in milk after 30 min. exposure. One-half of these were examined in the laboratories of the Chicago Department of Health, and 1/2 in the laboratories of the New York City Department of Health. Cultures from each of the 200 strains were killed by exposure to 140[degree] F. for 30 min. The majority of strains were killed at a temp. of 136[degree] or less. The resistant, probably pathogenic, non-hemolytic streptococcus found in cheese was not killed after 75 min. exposure to 145[degree] but was killed after 90 min. Cultures of Bacillus melitensis and B. abortus were killed after 10 min. exposure at 140[degree].