Annual report of the Australian Meningococcal Surveillance Programme 1996.

The Australian Meningococcal Surveillance Programme has undertaken meningococcal isolate surveillance by means of a collaborative laboratory-based initiative since 1994. Serogroup data have been enhanced by the addition of serotype and serosubtype information in 1996. Ninety-two per cent of the 297 invasive isolates of Neisseria meningitidis examined in 1996 were serogroup B or C. Serogroup B strains predominated in all States and Territories and were isolated from sporadic cases of meningococcal disease. Serogroup C isolates were prominent in New South Wales, Queensland and the Northern Territory, and were also associated with mainly sporadic cases of meningococcal disease. A number of case clusters also occurred in association with serogroup C strains. Although most sporadic cases of meningococcal disease showed a diversity of phenotypes, clusters of cases were noted with the phenotypes C:2a:P1.5 and C:2a:P1.2,5. The number of isolates with the phenotype B:4:P1.4 also increased in New South Wales and Queensland. The proportion of isolates showing decreased susceptibility to the penicillin group of antibiotics (minimal inhibitory concentration, MIC, 0.06 to 0.5 mg/L) increased to 74% in 1996. Three isolates showed reduced susceptibility to rifampicin.