Epidemiology of Streptococcus dysgalactiae subsp. equisimilis in tropical communities, Northern Australia.
Streptococcus dysgalactiae subsp. equisimilis (groups C and G streptococci [GCS/GGS]) is an increasingly recognized human pathogen, although it may follow indirect pathways. Prospective surveillance of selected households in 3 remote Aboriginal communities in Australia provided 337 GCS/GGS isolates that were emm sequence-typed. Lancefield group C isolates (GCS) were localized to specific households and group G isolates (GGS) were more evenly distributed. GCS/GGS was more frequently recovered from the throat than group A streptococci (GAS [S. pyogenes]) but rarely recovered from skin sores, and then only with Staphylococcus aureus or GAS. Symptomatic GGS/GGC pharyngitis was also rare. Specific emm sequence types of GCS/GGS did not appear to cycle through the communities (sequential strain replacement) in a manner suggesting acquisition of type-specific immunity. These communities already have high levels of streptococcal and poststreptococcal disease. GCS/GGS may increase in importance as it acquires key virulence factors from GAS by lateral gene transfer.
McDonald
Malcolm
M
Menzies School of Health Research, Charles Darwin University, Casuarina, Northern Territory, Australia. malcolm.mcdonald@menzies.edu.au
Towers
Rebecca J
RJ
Andrews
Ross M
RM
Carapetis
Jonathan R
JR
Currie
Bart J
BJ
D000293:Adolescent; D001315:Australia / Q000453:epidemiology; D002648:Child; D006801:Humans; D010614:Pharynx / Q000382:microbiology; D011159:Population Surveillance / Q000379:methods; D011446:Prospective Studies; D012213:Rheumatic Fever / Q000453:epidemiology / Q000382:microbiology; D012214:Rheumatic Heart Disease / Q000453:epidemiology / Q000382:microbiology; D012867:Skin / Q000382:microbiology; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013291:Streptococcus / Q000235:genetics / Q000302:isolation & purification*; D014329:Tropical Climate