Increasing severity of invasive group A streptococcal disease in Australia: clinical and molecular epidemiological features and identification of a new virulent M-nontypeable clone.
We conducted a 12-year review of all cases of group A streptococcal (GAS) bacteremia that were seen at Royal Children's Hospital in Melbourne, Australia, from 1982 through 1993. Forty-two cases were identified. There was a trend towards increased incidence of infections, as well as a clear increase in their severity, during the study period; more previously healthy children were affected during the last 6 years of the study (80% of cases) than during the first 6 years (47% of cases), and more complications occurred during the latter period than during the former (40% vs. 20%, respectively, with an 88% complication rate over the last 12 months). Seventy-four GAS isolates (41 invasive, 23 noninvasive, and 10 indeterminate) were analyzed. An M type 1 clone that was positive for the pyrogenic exotoxin A gene (speA) and that has been found to cause invasive disease in the Northern Hemisphere was most frequent among invasive isolates. Molecular typing also identified a genetically distinct strain that was virulent, mucoid, and M nontypable. Invasive GAS disease in Melbourne has become increasingly aggressive. Newer typing methods should be used in conjunction with traditional serotyping in order to maintain epidemiological surveillance of virulent strains.
Carapetis
J
J
Menzies School of Health Research, Casuarina, Australia.
Robins-Browne
R
R
Martin
D
D
Shelby-James
T
T
Hogg
G
G
D000293:Adolescent; D000328:Adult; D001315:Australia / Q000453:epidemiology; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology*; D001426:Bacterial Proteins; D015373:Bacterial Typing Techniques; D002648:Child; D002675:Child, Preschool; D005098:Exotoxins / Q000235:genetics; D005798:Genes, Bacterial; D006801:Humans; D007223:Infant; D008565:Membrane Proteins; D017720:Molecular Epidemiology; D012189:Retrospective Studies; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000145:classification / Q000235:genetics / Q000472:pathogenicity; D014774:Virulence
D001426:Bacterial Proteins; D005098:Exotoxins; D008565:Membrane Proteins; C117980:SpeA protein, Streptococcus pyogenes; C027951:erythrogenic toxin