Simple Medium for Assessing Quantitative Production of Histamine by Enterobacteriaceae

A simple medium was developed for the quantitative assessment of the histamine-producing capability of Enterbacteriaceae . This medium was formulated from trypticase soy broth fortified with 2.0% histidine, pH 6.3 (TSBH). Histamine production by Klebsiella pneumoniae was optimal under those conditions and other histamine-producing bacteria, such as Proteus morganii and Enterobacter aerogenes , also produced large quantities of histamine in TSBH. TSBH is superior to tuna fish infusion broth for studies on bacterial histamine production because it is simple and inexpensive to prepare, has a consistent composition, and is not dependent on the availability of high quality raw tuna. TSBH should be useful for studying the effectiveness of proposed methods for controlling bacterial histamine production. Histamine production by K. pneumoniae was reduced as the NaCl concentration of the TSBH was increased, with marked inhibition occurring at 5.5% NaCl.