Salmonella meleagridis: Dose Response Experiments

General Overview

Salmonella is a genus of rod-shaped, gram-negative, non-spore forming, predominantly motile enterobacteria . Many species of Salmonella have been isolated from eggs and egg products . Salmonella meleagridis is one of the most common serotype of Salmonella . Twenty human isolates of S. meleagridis had been identified in Canada so far during 1997.

http://www.cdc.gov/salmonella/

Summary Data

McCullough, and Eisele (1951) inoculated human volunteers orally with the S. Meleagridis strain I,II and III.

Recommended Model

Eexperiment number 238 is the recommended one as the strain I was more virulent than strain III.

Exponential and betapoisson model.jpg

ID	Exposure Route	# of Doses	Agent Strain	Dose Units	Host type	Μodel	LD50/ID50	Optimized parameters	Response type	Reference
238	oral (with eggnog)	11.00	strain I	CFU	human	beta-Poisson	1.68E+04	a = 3.89E-01 N₅₀ = 1.68E+04	infection	McCullough, N. ., & Elsele, C. . (1951). Experimental Human Salmonellosis: I. Pathogenicity of Strains of Salmonella Meleagridis and Salmonella Anatum Obtained from Spray-Dried Whole Egg. Oxford Journal of Infectious Diseases, 88(3). https://doi.org/https://doi.org/10.1093/infdis/88.3.278
240	oral (with eggnog)	4.00	strain III	CFU	human	beta-Poisson	5.24E+05	a = 8.85E-01 N₅₀ = 5.24E+05	infection	Muller, D. ., Edwards, M. L., & Smith, D. W. (1983). Changes in Iron and Transferrin Levels and Body Temperature in Experimental Airborne Legionellosis. The Journal of Infectious Diseases, 147, 2. https://doi.org/https://doi.org/10.1093/infdis/147.2.302

Highest quality

Exposure Route:

oral (with eggnog)

# of Doses:

11.00

Agent Strain:

strain I

Dose Units:

CFU

Host type:

human

Μodel:

beta-Poisson

LD50/ID50:

1.68E+04

Optimized parameters: a = 3.89E-01 N₅₀ = 1.68E+04

Response type:

infection

Reference:

Experimental Human Salmonellosis: I. Pathogenicity of Strains of Salmonella Meleagridis and Salmonella Anatum Obtained from Spray-Dried Whole Egg

**Human / *S. meleagridis* strain I data**
Dose	Infected	Non-infected	Total
12000	3	3	6
24000	4	2	6
52000	3	3	6
96000	3	3	6
155000	5	1	6
3E+05	6	0	6
720000	4	1	5
1150000	6	0	6
5.5E+06	5	1	6
2.4E+07	5	0	5
5E+07	6	0	6

**Goodness of fit and model selection**
Model	Deviance	Δ	Degrees of freedom	χ²_0.95,1 p-value	χ²_0.95,m-k p-value
Exponential	71.8	63.8	10	3.84 1.33e-15	18.3 1.98e-11
Beta Poisson	7.99	63.8	9	3.84 1.33e-15	16.9 0.535
Beta-Poisson fits better than exponential; cannot reject good fit for beta-Poisson.

**Optimized parameters for the beta-Poisson model, from 10000 bootstrap iterations**
Parameter	MLE estimate	Percentiles
Parameter	MLE estimate	0.5%	2.5%	5%	95%	97.5%	99.5%
α	3.89E-01	1.23E-01	1.74E-01	2.01E-01	1.12E+00	1.91E+00	3.82E+02
N₅₀	1.68E+04	7.98E+01	1.08E+03	2.27E+03	4.78E+04	5.71E+04	7.49E+04

Parameter scatter plot for beta Poisson model ellipses signify the 0.9, 0.95 and 0.99 confidence of the parameters.

beta Poisson model plot, with confidence bounds around optimized model