What is the infectious dose of salmonella?

Updated: Dec 20, 2019
  • Author: Alena Klochko, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Although the infectious dose varies among Salmonella strains, a large inoculum is thought to be necessary to overcome stomach acidity and to compete with normal intestinal flora. Large inocula are also associated with higher rates of illness and shorter incubation periods. In general, about 106 bacterial cells are needed to cause infection. Low gastric acidity, which is common in elderly persons and among individuals who use antacids, can decrease the infective dose to 103 cells, while prior vaccination can increase the number to 109 cells. [7]


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