MICROBIOLOGY: Sleuthing Streptococcus

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Science  28 Jan 2005:
Vol. 307, Issue 5709, pp. 485a
DOI: 10.1126/science.307.5709.485a

Streptococcal diseases have many disguises, ranging from minor sore throats to life-threatening toxic shock. The epidemiology of streptococcal diseases has long been problematic, manifesting as suddenly emerging and disappearing epidemics of disparate syndromes with no apparent therapeutic correlate. In a population-wide genomic study of 11 years of data from 255 isolates from Ontario, Canada, Beres et al. implicated the source of waves of invasive disease to the acquisition or loss of prophages, which rapidly generated unique combinations of virulence genes and their characteristic diseases: toxic shock, bacteremia, or necrotizing fasciitis. However, another 7-year Canadian study of 306 cases of invasive group A streptococcal infections revealed a population-based shift from soft tissue infections to pneumonia, especially in women. Hollm-Delgado et al. suggest that underlying conditions in the victims may be causing this shift. They found that the risk of soft-tissue streptococcal infections increased after varicella infections or drug injection, but ultimately could not explain the increase in pneumonia. However a statistical link could not be made between any particular serotype and specific clinical symptoms. It is possible that a prophage may be at work behind the scenes. — CA

Proc. Natl. Acad. Sci. U.S.A. 101, 11833 (2004); Emerg. Infect. Dis. 11, 77 (2005).

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