Characteristics of Haemophilus ducreyi in culture

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Abstract
Growth on different media and the influence of culture conditions were studied on 19 recently isolated strains of H. ducreyi, none of which had > 4 passages on artificial media. The results were compared with 10 laboratory strains, which had an unknown number of passages in vitro. For all strains, growth was best on 30% rabbit blood agar and on Bieling agar. The laboratory strains showed a tendency to grow better on chocolate agar than did the fresh isolates. Of 19 fresh clinical isolates, 12 were CO2 dependent; 2 needed extra moisture for growth. From the 10 laboratory strains, only 1 needed CO2 and none needed extra moisture. All 29 strains grew under anaerobic conditions. Of the 19 fresh clinical isolates, 12 grew at 22.degree. C, only 2 of the 10 laboratory strains grew at this temperature. The laboratory strains grew better than the fresh isolates at 37.degree. C; the optimal pH for all strains was 6.5-7.0. All strains showed starch aggregation.