Salmonella meleagridis: Dose Response Experiments

General Overview

Salmonella is a genus of rod-shaped, gram-negative, non-spore forming, predominantly motile enterobacteria (Chalker and Blaser 1988). Many species of Salmonella have been isolated from eggs and egg products (McCullough and Eisele 1951). Salmonella meleagridis is one of the most common serotype of Salmonella (Zaidi, McDermott et al. 2006). 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.^[1]

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	# of Doses	Agent Strain	Dose Units	Host type	Μodel	Optimized parameters	Response type	Reference
238	11	strain I	CFU	human	beta-Poisson	a = 3.89E-01 LD₅₀/ID₅₀ = 1.68E+04 N₅₀ = 1.68E+04	infection	McCullough, N. B., and C. W. Elsele. "Experimental Human Salmonellosis: I." Pathogenicity of Strains of Salmonella meleagridis and Salmonella anatum Obtained from Spray-Dried Whole Egg. 88 (1951): 3.
240	4	strain III	CFU	human	beta-Poisson	a = 8.85E-01 LD₅₀/ID₅₀ = 5.24E+05 N₅₀ = 5.24E+05	infection	Muller, D., M. L. Edwards, and D. W. Smith. "Changes in Iron and Transferrin Levels and Body Temperature in Experimental Airborne Legionellosis." The Journal of Infectious Diseases. 147 (1983): 2.

Best Fit

Experiment ID:

238

# of Doses:

Agent Strain:

strain I

Dose Units:

CFU

Host type:

human

Μodel:

beta-Poisson

Optimized parameters: a = 3.89E-01

LD₅₀/ID₅₀ = 1.68E+04
N₅₀ = 1.68E+04

Reference:

**Human / *S. meleagridis* strain I data** ^[1]
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