Hello Doaa,

Did you treat mice with antibiotic previous to infection? With antibiotic treatment, you should have plenty Stm in feces even with those inputs!

Otherwise, I usually infect mice orally with 10^8 Stm SL1344 (with or without antibiotic treatment actually). What mice model are you using?

Last thing, for plating Stm SL1344, I use LB supplemented with Streptomycin 200µg/ml. Are you using a similar concentration?

Best,

Thibault

No, i didn't use antibiotics before infection. 

I use b6 mice, they they start to die at day 4 if I used 10^8 dose, so I lowered the dose to 5x10^7 to see the phenotype. 

I use the same strain as u. However, I add only streptomycin with 100ug/ml  to  LB 

Hi Doaa,

How are you trying to culture the Salmonella from the feces? What we usually do is take a fresh fecal pellet from the mouse and put it directly into 500µL of 1X PBS. We then homogenize the fecal pellet and then do a 1/10 serial dilution down. We spot plate on LB-Strep (200µg/mL like Thibault mentioned). For the neat plate, we plate 100µL. 

Have you checked how much you are inoculating your mice with? And via what route? Oral gavage?

--Kyler