Salmonella meleagridis: Dose Response Models

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Salmonella meleagridis

Author: Sushil Tamrakar


General overview of Salmonella and Salmonellosis

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]


Experiment serial number Reference Host type Agent strain Route # of doses Dose units Response Best fit model Optimized parameter(s) LD50/ID50
238* [1] human strain I oral, with eggnog 11 CFU infection beta-Poisson α= 3.89E-01 , N50 = 1.68E+04 1.68E+04
240 [1] human strain III oral, with eggnog 4 CFU infection beta-Poisson α = 8.85E-01 , N50 = 5.24E+05 5.24E+05
*This model is preferred in most circumstances. However, consider all available models to decide which one is most appropriate for your analysis.


*Recommended Model

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


Exponential and betapoisson model.jpg



Optimization Output for experiment 238 (Salmonella meleagridis)

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
χ20.95,1
p-value
χ20.95,m-k
p-value
Exponential 71.8 63.8 10 3.84
1.33e-15
18.3
1.98e-11
Beta Poisson 7.99 9 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
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


Optimization Output for experiment 240 (Salmonella meleagridis)

Human/ S. meleagridis strain III data [1]
Dose Infected Non-infected Total
158000 1 5 6
1.5E+06 5 1 6
7680000 6 0 6
1E+07 5 1 6


Goodness of fit and model selection
Model Deviance Δ Degrees
of freedom
χ20.95,1
p-value
χ20.95,m-k
p-value
Exponential 7.81 5.51 3 3.84
0.019
7.81
0.0501
Beta Poisson 2.3 2 5.99
0.316
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
0.5% 2.5% 5% 95% 97.5% 99.5%
α 8.85E-01 1.78E-01 2.91E-01 3.68E-01 1.40E+03 1.71E+03 8.24E+03
N50 5.24E+05 4.71E+04 1.20E+05 1.92E+05 1.19E+06 1.39E+06 1.90E+06


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



References

  1. 1.0 1.1 1.2 1.3 1.4 McCullough NB, Eisele CW (1951) Experimental human salmonellosis. II. Immunity studies following experimental illness with Salmonella meleagridis and Salmonella anatum. Journal of immunology (Baltimore, Md. : 1950) 66(5): 595-608.

Chalker RB and Blaser MJ (1988) A Review of Human Salmonellosis: III. Magnitude of Salmonella Infection in the United States. Reviews of Infectious Diseases 10(1), 111-124.

McCullough NB and Eisele CW (1951) Experimental Human Salmonellosis: II. Immunity Studies Following Experimental Illness with Salmonella Meleagridis and Salmonella Anatum. The Journal of Immunology 66(5), 595-608.

McCullough NB and Eisele CW (1951) Experimental Human Salmonellosis: III. Pathogenicity of Strains of Salmonella newport, Salmonella derby, and Salmonella bareilly Obtained from Spray-Dried Whole Egg. The Journal of Infectious Diseases 89(3), 209-213.

Zaidi MB, McDermott PF, Fedorka-Cray P, Leon V, Canche C, Hubert SK, Abbott J, León M, Zhao S, Headrick M and Tollefson L (2006) Nontyphoidal Salmonella from Human Clinical Cases, Asymptomatic Children, and Raw Retail Meats in Yucatan, Mexico. Clinical Infectious Diseases 42(1), 21-28.