Hemolytic Phage-Bacterium Conjugates

The production of hemolytic bacteriophage-bacterium conjugates was reported by Friedberger and Vallen. 1 Apparently identical aggressive conjugates were afterwards isolated from clinical material. 2 The non-hemolytic microörganisms which can be transformed into erythrolytic variants by phage-“hybridization” include B. typhosus, B. dysenteriœ, B. paratyphosus, B. suipestifer, S. cholerœ, and B. coli. In order to obtain material for an immunochemic and genetic study of such “hybrids,” we have tested the erythrolytic powers of 75 conjugates, formed by combining 11 local typhoid strains with 7 demonstrably active antityphoid bacteriophages. Each bacteriophage was first grown for 3 to 6 test-tube generations on each of the 11 typhoid strains. In 67 of the 77 combinations powerful lysis was noted. The 67 resulting apparently completely lysed typhoid cultures were incubated for an additional period of 48 to 72 hours. In 65 of the tubes an overgrowth with phage-resistant B. typhosus took place. Hemolytic titers of these 65 aggressive overgrowths are recorded in Table I.

The table shows that only 23 (30%) of the phage-resistant B. typhosus variants produce demonstrable lysis, and that only 8 (10%) of them give lytic reactions equal to that of fairly active hemolytic streptococci (++). Active proliferation of bacteriophage in the 52 hemolytically negative phage-bacterium complexes was demonstrated by phage-titration of filtrates.