Variation in Peroxide Production by Beta Hemolytic Streptococci

Abstract

The peroxide-forming bacteria have been shown by McLeod and Gordon' to be the pneumococci, streptococci, lactic acid bacilli, certain sarcinal forms and the anaerobes. These organisms also fail to produce catalase, thereby permitting an accumulation of peroxide to which their delicacy in subculture is attributable. Exclusion from air and light, and growth in mediums containing tissue fluids which supply catalase, or the addition of certain reducing substances such as cystein or sodium thioglycollate, are therefore necessary for the growth and preservation of these organisms. Demonstration of peroxide production by bacteria growing in liquid medium can be made by the peroxidase test.2,3 If only small quantities are formed, however, and at irregular intervals (as is the case with the streptococci) this test is unreliable, as shown by McLeod and Gordon4 who recommended chocolate agar on which the cumulative action of very small quantities of peroxide is manifested by a green discoloration. Penfold5 was the first to show that on benzidine blood agar peroxide-producing pneumococci and streptococci produced a black or brown pigment which he concluded was formed by the oxidation of the amino bodies of the benzidine by peroxide produced by the organisms. Peroxidase, contained in blood, was necessary for the test. Nonperoxide-producing organisms did not give the reaction. Although Penfold found that all strains of pneumococci and streptococci tested gave a positive reaction with benzidine, certain streptococcal strains gave variable results. This variability was shown by some strains giving all black colonies at one time and, at other times, a mixture of black and white colonies. Attempts to develop permanent black and white cultures of these strains were unsuccessful, and he concluded that the power to form peroxide is an erratic function of certain strains of hemolytic streptococci. Avery and Morgan,' using the peroxidase test on broth cultures, reported peroxide production by all pneumococcus cultures and by 15 of 23 strains of hemolytic streptococci. The observation of McLeod and Gordon7 that streptococci produced peroxide at a later period than pneumococci was confirmed by the former workers who showed that in