The purpose of an enrichment broth is to amplify very low levels of a specific bacterium within 24 hours so it can be more readily identified and isolated by a subsequent methodology. In situations where cells of the targeted bacterium are very low and injury is high, such cells must undergo repair without deleterious effects. The broth must also contain selective agents to suppress background growth which can interfere with the isolation of the target bacterium. Because of the low incidence of Enterobacter sakazakii (E.s.) in foods most environmental sources as well, a difficulty exists in developing a reliable selective enrichment procedure that permits the proliferation of both injured and non-injured E.s. while suppressing the growth of competing flora.

1. Our broth supported the growth of 100% of the 63 E.s. strains tested, where as 8% either grew poorly or failed to grow in a standard selective broth (EE broth).