Bacterial colonization in vivo

The protocol for Bacterial colonization in vivo

1. We collected the major organs of mice intravenously injected with bacteria injection (5x10⁶ per mouse) at desired time points. The major organs including heart, liver, spleen, lung, kidney, and tumor, were extracted, weighed, and homogenized at 4°C in sterile PBS (1ml, pH = 7.2). 

2. The homogenized organs were serially diluted in multiples of 10. Samples with three consecutive dilution multiples were selected according to the preliminary experiment so as to control the bacteria count between 20 and 300 in one of 100 ml diluted samples. 100 ml of undiluted samples or diluted samples was plated on LB plates in 3 individual times. 

3. After 6-12 hours of incubation, bacterial colonies were counted and imaged. The bacterial titer (CFU per gram of tissue) was calculated with colony counts, dilution ratios and tissue weights.