Sequence Analysis of the Variable Number Tandem Repeat in Staphylococcus aureus Protein A Gene - Bacterial Pathogenesis: Methods and Protocols - page 283

The recent study by Cooper and Feil revisited the population structure of S.
aureus , as derived by MLST analysis, by additionally comparing 33 gene loci
representing various functional categories in 30 genetically characterized strains
(49) . Approximately 17.8 kb of DNA sequence data for each strain produced
an unrooted Bayesian tree that resembles the population structure established
by MLST but with higher resolution and without unresolved branches. Their
data sub-divides the S. aureus species into three genetic groups (1a, 1b, and 2),
and within each group, MLST branches can be mapped, thus providing a
robust framework onto which spa types may be assigned ( see Fig. 5 ). One
could envision the future naming of spa types to include both the genetic
group as well as the MLST branch designation, thereby providing phyloge-
netic structure to spa -typing results. Molecular approaches such as spa typing
can therefore add further resolution to phylogenetically determined lineages
or clusters to elucidate microevolutionary processes that may have biomedical
significance; in turn, phylogenetic analysis can root molecular epidemiology-
derived genotypes (e.g., USA300) into broad groups that share informative
biologic traits and further our understanding of genotype-phenotype relation-
ships.
References
1. Lowy, F. D. (1998) Staphylococcus aureus infections. N. Engl. J. Med . 339 ,
520-532.
2. Centers for Disease Control and Prevention. (2004) National Nosocomial Infections
Surveillance (NNIS) System Report, data summary from January 1992 through
June 2004, issued October 2004. Am. J. Infect. Control 32 , 470-485.
3. Said-Salim, B., Mathema, B., and Kreiswirth, B. N. (2003) Community-acquired
methicillin-resistant Staphylococcus aureus : an emerging pathogen. Infect. Control
Hosp. Epidemiol . 24 , 451-455.
4. Grundmann, H., Aires-de-Sousa, M., Boyce, J., and Tiemersma, E. (2006)
Emergence and resurgence of meticillin-resistant Staphylococcus aureus as a
public-health threat. Lancet 368 , 874-885.
5. Maiden, M. C., Bygraves, J. A., Feil, E., Morelli, G., Russell, J. E., Urwin, R.,
Zhang, Q., Zhou, J., Zurth, K., Caugant, D. A., Feavers, I. M., Achtman, M.
and Spratt, B. G. (1998) Multilocus sequence typing: a portable approach to the
identification of clones within populations of pathogenic microorganisms. Proc.
Natl. Acad. Sci. U.S.A . 95 , 3140-3145.
6. Tenover, F. C., Arbeit, R. D., Goering, R. V., Mickelsen, P. A., Murray, B. E.,
Persing, D. H., and Swaminathan, B. (1995) Interpreting chromosomal DNA
restriction patterns produced by pulsed-field gel electrophoresis: criteria for
bacterial strain typing. J. Clin. Microbiol . 33 , 2233-2239.