Review of invasive group A streptococci in Queensland, Australia 1996-2004

Streptococcus pyogenes (GAS) is an important human pathogen that causes a variety of diseases. Since the mid-1980s, there have been reports from around the world of an increase in the incidence of severe invasive GAS infections with associated morbidity and mortality. The aim of the present study was to carry out an epidemiological analysis of invasive GAS infections in Queensland over the 9-year period from 1996 to 2004. Epidemiological data including age, sex, indigenous status, concurrent illness, severity of disease, and whether community or nosocomial acquisition were also collected where possible. The 659 sterile site isolates were characterized by emm sequencing, antimicrobial susceptibility, presence of superantigen gene profiles, i.e., genes encoding for spe A, B, and C genes and biotyping using the API RapID 32Strep Kit. There were a total of 99 emm types among the 659 isolates. In the postcode < 4700, there were 57 emm types, with 14 emm types that only occurred in < 4700 area. In the > 4700 area, there were 86 emm types with 43 only occurring > 4700 area. Moreover, 102 isolates from non-sterile sites were also tested, of which 46 emm types were found with only 6 being found in the non-sterile isolates. In the sub-tropical region, emm 1 was most common at 17.9% with emm 28 at 10.4%. Antimicrobial susceptibility tests using E-Tests on 5% blood Mueller-Hinton agar was also done for penicillin, erythromycin, tetracycline, chloramphenicol and vancomycin. All isolates were sensitive to penicillin and vancomycin. There were significant differences in the characteristics of the isolates from the tropical and sub-tropical regions.