A Bacteriophage Active Against a Virulent Hemolytic Streptococcus.

Abstract

We reported 1 last year the finding of a bacteriophage against a virulent hemolytic streptococcus. Such a lytic principle active against streptococcus has been reported so rarely, if at all, that it seems desirable to state our results in some detail.

The organism against which the phage was originally active was isolated about 3 years ago from a spontaneous fatal infection in a stock rabbit. At autopsy, the animal showed marked thoracic lesions, myocarditis, pericarditis, bronchopneumonia, fibrino-purulent pleurisy, extensive empyema with relatively little grossly noticeable below the diaphragm save an acute splenic tumor. The organism was readily obtained in pure culture from these lesions and also from the heart's blood. It grows on sheep blood agar as a very moist, translucent, mucoid colony, somewhat similar to that of Pneumococcus mucosus, but it produces a wide zone of hemolysis on the plate. One cc. of a 12 hour broth culture will cause complete hemolysis of a 5 per cent suspension of washed sheep red blood cells when incubated for one hour at 37° C. It does not ferment inulin and is bile insoluble, so we consider it an example of a Streptococcus mucosus. It closely resembles the organisms found in cases of septic sore throat. The various fermentation reactions are recorded in Table I.

The organism is Gram positive, but is more readily decolorized than many streptococci, and, frequently, partially decolorized cocci may be observed in a chain of Gram positive organisms. It appears in chains of moderate length, the individual members of the chain usually being spherical and variable in size. Capsules can be readily demonstrated by any of the commonly used methods.

This organism proved virulent for other rabbits, causing a fatal septicemia in 5 to 7 days, when injected intravenously into full grown animals in amounts of .001 cc. of a broth culture.