A Selective Medium for the Primary Isolation of Haemophilus pertussis and Haemophilus parapertussis

SUMMARY: A description is given of a selective medium which supports the growth of Haemophilus pertussis and Haemophilus parapertussis and largely inhibits the growth of Haemophilus influenzae. The medium contains horse-meat extract, horse blood, salt agar, 2 μg. 4:4′-diamidino-diphenylamine-dihydrochloride/ml. and 0·3 unit penicillin/nil. The medium is of value in the primary isolation of H. pertussis and H. parapertussis.