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Experiment ID
278
Pathogen
Staphylococcus aureus
Contains Preferred Model
Yes
Reference
Lawin-Brüssel, C. A., Refojo, M. F., Leong, F. L., Hanninen, L. ., & Kenyon, K. R. (1993). Effect of Pseudomonas aeruginosa concentration in experimental contact lens-related microbial keratitis. Cornea, 12, 1.
Exposure Route
subcutaneous
Response
infection
Host type
human
# of Doses
6.00
Dose Units
CFU/cm2
Μodel
exponential
k
7.64E-08
LD50/ID50
9.08E+06
Description
Human/Staphylococcus aureus 
Dose Infected Non-infected Total
2430000 4 16 20
6270000 8 12 20
1.27E+07 13 7 20
2.5E+07 14 6 20
3.34E+07 19 1 20
3.91E+07 20 0 20

 

Goodness of fit and model selection
Model Deviance Δ Degrees 
of freedom		 χ20.95,1 
p-value 		χ20.95,m-k 
p-value
Exponential 5.52 5.36e-05 5 3.84 
0.994 		11.1 
0.356
Beta Poisson 5.52 4 9.49 
0.238
Exponential is preferred to beta-Poisson; cannot reject good fit for exponential.

 

Optimized k parameter for the exponential model, from 10000 bootstrap iterations
Parameter MLE estimate Percentiles
0.5% 2.5% 5% 95% 97.5% 99.5%
k 7.64E-08 5.67E-08 6.19E-08 6.41E-08 1.00E-07 1.02E-07 1.35E-06
ID50/LD50/ETC* 9.08E+06 2.70E+06 6.79E+06 6.93E+06 1.08E+07 1.12E+07 1.22E+07
*Not a parameter of the exponential model; however, it facilitates comparison with other models.

 

Parameter histogram for exponential model (uncertainty of the parameter)

Exponential model plot, with confidence bounds around optimized model

References

  • Rose, J. B., & Haas, C. N. (1999). A risk assessment framework for the evaluation of skin infections and the potential impact of antibacterial soap washing. American Journal of Infection Control, 27, 26-33. https://doi.org/10.1016/s0196-6553(99)70039-8