General Overview
Listeria monocytogenes is a food-borne pathogen responsible for the illness listeriosis. This disease is especially severe for susceptible people, including fetuses and immunocompromised individuals .
Summary Data
Smith et al.(2008) studied dose-response model for Listeria monocytogenes induced stillbirths in nonhuman primates . Thirty-three pregnant rhesus monkeys (Macaca mulatta) were identified at 30 gestation days (gd) and L. monocytogenes was administered by nasogastric intubation. Animals were observed daily for changes in behavior or activity or signs of illness such as diarrhea. Similarly, Williams et al ( 2007 and 2009) explored fetal mortality in guinea pigs after oral exposure . Timed-pregnant guinea pigs were inoculated L. monocytogenes with whipping cream and the doses ranges from 104 CFU to 108 CFU. The animals were sacrificed on gestation day.
Recommended Model
It is recommended that pooled model of experiment 289 and 290 pooled should be used as the best dose response model. More data means better fit.
| ID | Exposure Route | # of Doses | Agent Strain | Dose Units | Host type | Μodel | LD50/ID50 | Optimized parameters | Response type | Reference |
|---|---|---|---|---|---|---|---|---|---|---|
| 289 | intubation | 8.00 | CFU | rhesus monkey | beta-Poisson | 8.26E+08 | a = 0.04 N50 = 8.26E+08 | stillbirths | ||
| 290 | intubation | 5.00 | CFU | guinea pig | beta-Poisson | 4.67E+07 | a = 0.0936 N50 = 4.67E+07 | fetal mortality | ||
| 292 | oral | 6.00 | F5817 | CFU | beta-Poisson | a = 0.253 N50 = 277 | infection |
| Model | Deviance | Δ | Degrees of freedom |
χ20.95,1 p-value |
χ20.95,m-k p-value |
| Exponential | 9.88 | 6.48 | 5 | 3.84 0.011 |
11.1 0.0788 |
| beta Poisson | 3.4 | 4 | 9.49 0.494 |
||
| beta-Poisson fits better than exponential; can not reject good fit for beta-Poisson | |||||
| Parameter | MLE Estimate | 0.5% | 2.5% | 5% | 95% | 97.5% | 99.5% |
| α | 6.95E-01 | 2.69E-01 | 3.39E-01 | 3.78E-01 | 2.56E+0 | 2.28E+01 | 1.18E+03 |
| N50 | 3.39E+03 | 3.58E+01 | 2.47E+02 | 4.67E+02 | 1.09E+04 | 1.26E+04 | 1.85E+04 |