Neisseria meningitidis is the causal agent of epidemic bacterial meningitis and sepsis. It is carried asymptomatically in the nasopharynx of healthy individuals but can occasionally cross the mucosal membrane resulting in life threatening illness. In 2017, the rate of invasive meningococcal disease notifications in Australia was 1.6 per 100 000, the highest since 2006. This increase in disease notifications is overwhelmingly due to an increased prevalence of serogroup W strains. The highest risk demographic are infants under the age of one and adolescents aged 15-21 years. This is due to immature immune response in infants, and higher transmission and carriage rates of meningococci in adolescents compared to the rest of the population.
In 2017, Western Australia, commenced a quadrivalent A/C/W/Y vaccination program targeting 15-19 year-old adolescents. Despite this vaccination programme, the rate of meningococcal notifications did not decrease with a total of 20 notifications as of 31st January 2018. A pilot meningococcal carriage study was commenced to determine the carriage rate of at risk individuals as a prelude to a larger state-based vaccination intervention in this age group to commence in August 2018.
Pharyngeal swabs were collected from 400 university students primarily aged 21-25 years. These swabs were used to inoculate GC-Lect selective media, and colonies that grew after 18 hrs incubation were tested by Gram stain and oxidase test to identify Neisseria sp. To confirm identification of N. meningitidis, sodC Syber qPCR for the gene in N. meningitidis with melt-curve analysis and MALDI-TOF were used. Of the oxidase positive isolates, 5.5% were confirmed as N. meningitidis (5.5%). The other species identified were Kingella dentrificans, Rothia sp, Capnocytophaga sputigena, Moraxella catharrhalis and Neisseria. lactamica. There was a 100% congruence of the PCR for sodC and MALDI-TOF assignments indicating that the molecular test was highly specific for cultured organisms.