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B F MASSELL

Publications and source records attributed to B F MASSELL.

At least 19 recordsLinked to original sources
PubMed1963

EFFECT OF SUBLETHAL CONCENTRATIONS OF PENICILLIN ON THE VIRULENCE AND ANTIGENIC COMPOSITION OF GROUP A STREPTOCOCCI.

Michael, J. Gabriel (House of the Good Samaritan, Children's Hospital Medical Center, Boston, Mass.), Benedict F. Massell, and Robert E. Perkins. Effect of sublethal concentrations of penicillin on the virulence and antigenic composition of group A streptococci. J. Bacteriol. 85:1280-1287. 1963.-Virulent strains of group A streptococci were grown in sublethal concentrations of penicillin and tested for possible changes in colonial morphology, virulence, and antigenic composition. After overnight growth in broth containing penicillin, there was a marked reduction in precipitable group A and M protein content of the bacteria. Upon transfer to broth without antibiotic, the streptococci regained their ability to produce these substances. After multiple transfers in broth containing non-bactericidal levels of penicillin, variants developed which lacked group and type substances and which were also relatively resistant to penicillin. These variants were avirulent for mice and susceptible to the bactericidal action of normal human blood. Two of three strains tested, when grown on blood agar, failed to produce beta hemolysis. The mutants produced by multiple transfers in broth containing small amounts of penicillin, when passed through mice, regained all of their original properties.

Animals↗
PubMed1962

Factors involved in the induction of non-specific resistance to streptococcal infection in mice by endotoxin.

Endotoxins derived from several species of Gram-negative bacteria, while inducing non-specific resistance to typhoid bacilli in mice, failed to increase the resistance of these animals to infection with virulent strains of Group A streptococci. However, if administration of endotoxin was followed by injection of minute amounts of type-specific antiserum, a substantial degree of protection against the streptococcal pathogen was obtained. The same amount of type-specific antiserum given to the animals by itself did not have any effect on the outcome of the streptococcal infection. Fresh rabbit blood, obtained from animals pretreated with endotoxin, together with anti-M protein immune serum, was found strongly bactericidal for streptococci. These observations suggest that, at least with regard to streptococcal infection, both humoral and cellular factors are required for induction of non-specific resistance.

Animals↗