Nitrocefin is a chromogenic cephalosporin substrate routinely used to detect the presence of beta-lactamase enzymes produced by various microbes.

Beta-lactamase mediated resistance to beta-lactam antibiotics such as penicillin is a widespread mechanism of resistance for a number of bacteria including members of the family Enterobacteriaceae, a major group of enteric Gram-negative bacteria.

After hydrolysis of the amide bond, the antibiotic lacks the ability to bind bacterial PBPs and is rendered useless.

Visual detection of this process is essentially impossible with most cephalosporins because the shift of ultraviolet absorption from the intact versus hydrolyzed product occurs outside of the visible spectrum.

[1] The following assays describe methods in which nitrocefin can be used to detect beta-lactamase enzymes using inexpensive materials and equipment.