A comparison of three rapid methods for the detection of beta-lactamase activity in Haemophilus influenzae

Three methods for rapidly detecting beta-lactamase activity in Haemophilus influenzae are compared. The chromogenic cephalosporin method was found to be the most easily performed and the reagents could be stored for up to three weeks. The phenol red method was simple to perform but the iodometric method was more time consuming. All three tests gave identical results.