Capsular hyaluronic acid in Pasteurella multocida type A and its counterpart in type D

Hyaluronic acid was demonstrated in the capsule extract of 39/39 Pasteurella multocida type A strains by sodium chloride gradient chromatography followed by Alcian blue staining, and by a turbidometric method using acidified horse serum. Treatment with hyaluronidase from various sources eliminated these reactions. An Alcian blue staining substance of closely similar chromatographic properties occurred in capsule extracts of 14/16 type D strains but it resisted hyaluronidase and was thought to be an acidic polysaccharide differing from the hyaluronic acid of type A. Turbidometric values were lower than with type A strains, but were unaltered by hyaluronidase treatment. The type D substance could be precipitated from capsule extract by acriflavin. Both type A and D strains were mucoid and displayed large capsule zones in stained preparations. Photomicrographic measurements showed that hyaluronidase treatment of cell suspensions markedly reduced capsule dimensions of type A but not type D strains. When type A strains were cross streaked against a hyaluronidase + Staphylococcus aureus, their growth became non-mucoid at the intersection: mucoid type D strains were unaffected. Neither hyaluronic acid nor the hyaluronidase resistant type D substance could be detected in type B or E strains.