Biology Reference
In-Depth Information
3.6. Data Analysis
To test for significance between data from animals grouped based upon the
strain of infecting GAS (wild-type or mutant), we use generalized estimating
equations to analyze the repeated binary outcomes in the data
(23)
.A
P
value
< 0.05 is considered significant.
4. Notes
1. Occasionally, a small amount of blood is visible in the posterior pharynx of the
animal as a result of the infection; this is to be avoided if possible when swabbing.
Blood on the throat swab provides a nutrient source that can enable GAS to
replicate following isolation but prior to plating for CFUs, thus skewing the data.
2. The presence of blood at the posterior pharynx may serve as a useful additional
clinical symptom and should be noted for each time-point for each animal.
3. Animals may require an increased dose of ketamine as the experiment progresses
to overcome resistance development (increase from 10 mg/kg to 14 mg/kg).
4. Cynomolgus macaque tonsils are routinely larger in size than human tonsils, and
hence it is normal for macaques to have pre-infection tonsil size scores of +1 or +2.
5. All tubes should be pre-labeled to prevent confusion during sample isolation. We
also strongly recommend using color-coded tubes for each of the sample types
isolated (red, blood; yellow, throat swab; blue, saliva; and white, nasal wash).
6. A small flashlight may be useful to illuminate the macaque posterior pharynx
during clinical scoring of disease.
7. Additional confirmation that throat-swab recovered bacteria are GAS can be
gained by using a GAS agglutination kit. We have used the BD BBL Streptocard
Acid Latex Test kit with good success.
References
1. Cunningham, M. W. (2000). Pathogenesis of group A streptococcal infections.
Clin. Microbiol. Rev
.
13
, 470-511.
2. Musser, J. M. and Krause, R. M. (1998). The revival of group A streptococcal
diseases, with a commentary on staphylococcal toxic shock syndrome, p. 185-218.
In R.M. Krause (ed.),
Emerging Infections
. Academic Press, San Diego, CA.
3. Bisno, A. L., Rubin, F. A., Cleary, P. P., and Dale, J.B. (2005). Prospects for
a group A streptococcal vaccine: rationale, feasibility, and obstacles-report of a
National Institute of Allergy and Infectious Diseases workshop.
Clin. Infect. Dis
.
41
, 1150-1156.
4. Carapetis, J. R., Steer, A. C., Mulholland, E. K., and Weber, M. (2005). The global
burden of group A streptococcal diseases.
Lancet Infect. Dis
.
5
, 685-694.
5. Musser, J. M. and DeLeo, F. R. (2005). Toward a genome-wide systems biology
analysis of host-pathogen interactions in group A
Streptococcus
.
Am. J. Pathol
.
167
, 1461-1472.
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