Comparison of enrichment media for recovery of Salmonella enterica after storage at various temperatures and alkaline stress exposure

Abstract

Rectal swabs containing Salmonella enterica may be exposed to desiccation stress while awaiting laboratory isolation. Growth of injured S. enterica is inhibited on selective media but the extent to which this varies across different media remains unclear. After storage at 25 °C, we compared growth recovery using four enrichment media and revealed that log 2.7 CFU and > log 4.0 CFU was required to confirm the growth of monophasic S. enterica Typhimurium K13-4-49 in buffered peptone water and selective enrichment media (Hajna tetrathionate broth, tetrathionate broth, and modified semisolid Rappaport agar for stab culture), respectively. Since < log 1.7 CFU was required for all four media, we recommend sample storage at ≤ 4 °C or the application of transport medium.