Invasive group A streptococcal disease in North Queensland (1996 - 2001).

BACKGROUND & OBJECTIVES: The incidence of group A streptococcal (GAS) invasive infections have been increasing worldwide. The aim of this study was to characterize clinical and microbiological features of isolates obtained from invasive GAS infections in North Queensland, Australia between 1996 and 2001. METHODS: Clinical and demographic data were collected prospectively. Isolates were biotyped, emm sequenced, M typed and tested for antibiotic sensitivity using E-test. Detection of the presence of the streptococcal pyrogenic exotoxin (spe) and fibronectin binding protein (prtF1) genes was also carried out. RESULTS: There were 109 isolates from blood and sterile sites. All isolates were sensitive to penicillin. Tetracycline and erythromycin resistance was seen in 11 and 2.7 per cent of isolates respectively. The isolates were evenly distributed by age and sex. The overall mortality was 7 per cent and there were 18 cases of streptococcal toxic shock syndrome (STSS) in which the mortality was 22 per cent. Indigenous patients had a crude incidence rate of 82.5 per 100,000 per year compared with 10.3 per 100,000 per year in the non-indigenous patients. There was no predominance of emm / M type or association of spe type with STSS. There was also no relationship between the presence of the prtF1 gene and invasive disease. INTERPRETATION & CONCLUSION: Invasive group A streptococci from North Queensland are similar to those from the Northern Territory of Australia in that no single strain is predominant. The indigenous population is overrepresented. Invasiveness and the development of streptococcal toxic shock is not related to the presence of the prtF1 gene or spe a or c.

Donor valves as substitutes for heart valve replacement.

The main problems of heart valve replacement in Sri Lanka are the cost of prosthetic valves and anticoagulant related complications. The use of human donor heart valves (homografts; allogeneic heart valves [AHV]) will alleviate these shortcomings. Recipients of AHV do not require anticoagulant therapy. Moreover, cryopreservation of AHV offers the opportunity for the storage of valves for an extended length of time with the preservation of valve integrity which is essential for their function after implantation. A donor valve bank can potentially provide diameter matched valves for recipients. Current research suggests that the adverse immunological reactions initiated by AHV cause tissue degeneration in a proportion of these implants. However, the grafts may be improved before implantation during the disinfection and storage of the valves. In this essay an overview on the advantages of using AHV, current concepts of valve banking, recent advances in the understanding of AHV immunogenicity, emerging techniques for immunomodulation of AHV and the possibility of setting up a donor heart valve bank in Sri Lanka are discussed.