Superiority of hypertonic culture medium for detection of Haemophilus influenzae by the BACTEC procedure

Abstract

A comparison of hypertonic (sucrose), aerobic, and anaerobic media for the detection of eight recent clinical isolates of Haemophilus influenzae type b by the BACTEC procedure revealed that the hypertonic medium, without exception, yielded diagnostic growth index values of 30 or above from 4 to 24 h earlier than did the other media. This culture medium was also superior when an increase in growth index units of 10, before a value of 30 was reached, was taken as a criterion. The number of colony-forming units increased more rapidly in the hypertonic medium as compared with the other media. These results, together with limited observations on blood cultures from patients, suggest that the sucrose medium may permit earlier detection of H. influenzae bacteremia than the aerobic medium, particularly since a growth index of 20 rather than 30 is used for the indication of bacterial growth.