Background
Nitrocefin is a chromogenic cephalosporin which has been found to be effective in detecting all known ß-lactamase enzymes. ß-lactamase enzymes hydrolyse the amide bond in the ß-lactam ring of Nitrocefin resulting in a distinctive colour change from yellow to red.
Nitrocefin discs are intended for use in the rapid testing of isolated colonies of Neisseria gonorrhoeae, Moraxella catarrhalis, Staphylococcus spp., Haemophilus influenzae and anaerobic bacteria, notably Bacteroides spp.
The Nitrocefin test is of little use for closely related taxonomic groups of organisms e.g. members of the family Enterobacterales. This is because organisms within a taxonomic group or even a single strain may produce a diversity of ß-lactamase enzymes with different substrate specificities.