Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2022

A pilot study of meningococcal carriage among Aboriginal and Torres Strait Islander people in the Pilbara: implications for future studies. (82442)

August Mikucki 1 , Emma Catchpole 1 , James Tran 1 , Heather Lyttle 2 , Christopher Mullally 3 , Noor-Ul-Huda Ghori 1 , Mark Nicol 1 , Geoffrey Coombs 3 , Shakeel Mowlaboccus 3 , Charlene Kahler 1
  1. The Marshall Centre for Infectious Diseases Research and Training, The University of Western Australia, Perth, WA, Australia
  2. WA Country Health Service Pilbara, Western Australian Government Department of Health, Pilbara, WA, Australia
  3. College of Science, Health, Engineering and Education, Murdoch University, Perth, WA, Australia

The genus Neisseria contains 10 species which colonise the human nasopharynx. N. gonorrhoeae and N. meningitidis (Nme) are pathogens, causing the STI gonorrhoea and invasive meningococcal disease (IMD), respectively. IMD is most commonly caused by serogroups A, B, C, W, X, and Y, whereas other serogroups or capsule-null (cnl) are usually harmlessly carried. The Pilbara region of WA had an increased rate of IMD in 2018/19 compared to the rest of WA (11.7 vs 1.2 cases/100,000 population).

Our study aimed to determine the meningococcal carriage rate in the region, and to improve the sensitivity of detection in remote studies using molecular techniques. Secondarily, we sought to validate qPCR-based detection of commensal Neisseria spp. in nasopharyngeal samples.

Participants (n=342, 10-32 y/o) were recruited during October-December 2019 at various sites across northern WA. Two swabs were collected from the pharynx and transported to Perth. Swabs were screened for Nme by direct culture on selective agar or by non-selective outgrowth followed by DNA extraction and qPCR. Novel qPCR primers targeting an essential gene, dsbD, in six commensal Neisseria spp. were validated and tested against a subset of samples.

Non-specific outgrowth improved detection: whilst 3 samples had culturable Nme, 114 (34%) samples were qPCR positive. The most abundant serogroups were cnl (63%) and serogroup B (33%). A significant association (Fisher’s exact test, p < 0.05) between age and carriage was observed. Commensal Neisseria probes were found to be sensitive, however some cross-reactivity between Neisseria spp. was observed. The relative point prevalence of each Neisseria spp. assessed was as follows: N. mucosa/oralis>N. subflava>N. polysaccahrea/bergeri/lactamica>N. meningitidis/N. gonorrhoeae.

In conclusion, detection of meningococcal carriage in remote settings is feasible using qPCR. The high rate of serogroup B carriage suggests that the use of serogroup B vaccines may be beneficial for public health in the region. Finally, our results suggest qPCR-based detection of commensal Neisseria is possible, but further efforts to design species-specific primers are required.