Difference between revisions of "Salmonella meleagridis: Dose Response Models"

From QMRAwiki
Jump to: navigation, search
Line 23: Line 23:
 
{{DRSummaryTableEnd}}
 
{{DRSummaryTableEnd}}
  
a:[[File:Exponential and betapoisson model.jpg|thumb|none|550px]]
+
[[File:Exponential and betapoisson model.jpg|thumb|none|550px]]
  
  

Revision as of 18:14, 23 August 2012

Salmonella enterica serotype 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, that cause more than 104 cases of infections per year in the United States. Salmonellosis is an important medical problem; although infection with non-typhoid Salmonella often causes mild self-limited illness, severe sequelae including death may occur, particularly in immunocompromised hosts. The incidence of salmonellosis is higher in developing than in developed countries and in developing countries, food handlers may be a reservoir for further transmission of infection (Chalker and Blaser 1988).

Many species of Salmonella have been isolated from eggs and egg products (McCullough and Eisele 1951). Salmonella enterica serotype Meleagridis is one of the most common serotypes of Salmonella (Zaidi, McDermott et al. 2006). Twenty human isolates of S. Meleagridis had been identified in Canada so far during 1997.



Summary Data

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


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 organisms infection beta-Poisson α= 3.89E-01 , N50 = 1.68E+04 1.68E+04
240 [1] human strain III oral, with eggnog 4 organisms 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.
Exponential and betapoisson model.jpg



Optimization Output for experiment 238

Human / Salmonella 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

Human/ Salmonella 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



Summary

The data set of Salmonella Meleagridis strain II failed to show test of trend and hence was not analyzed. Strain II and strain III could not be pooled.



References

  1. 1.0 1.1 1.2 1.3 ADDFULLREFERENCEHERE Cite error: Invalid <ref> tag; name "McCullough_and_Elsele.2C1951" defined multiple times with different content Cite error: Invalid <ref> tag; name "McCullough_and_Elsele.2C1951" defined multiple times with different content Cite error: Invalid <ref> tag; name "McCullough_and_Elsele.2C1951" defined multiple times with different content

McCullough, N. B. and C. W. Eisele (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.

McCullough, N. B. and C. W. Eisele (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, M. B., P. F. McDermott, et al. (2006). "Nontyphoidal Salmonella from Human Clinical Cases, Asymptomatic Children, and Raw Retail Meats in Yucatan, Mexico." Clinical Infectious Diseases 42(1): 21-28.