Molecular characterisation of Neisseria gonorrhoeae associated with disseminated gonococcal infections in Queensland, Australia: a retrospective surveillance study.

OBJECTIVES: Gonorrhoea caused by Neisseria gonorrhoeae is the second most notified sexually transmitted infection (STI) in Australia and the case numbers for this STI have been increasing globally. Progressive gonococcal infection may lead to disseminated gonococcal infection (DGI), which causes significant morbidity among patients. This study aims to examine the genetic diversity of N. gonorrhoeae isolates collected in Queensland from January 2010 to August 2015 and to determine factors associated with DGI in Queensland. DESIGN: Retrospective surveillance study for epidemiological purposes. SETTING: All gonorrhoeae isolates referred by private and public pathology laboratories to the state of Queensland, Australia Neisseria reference laboratory. METHODS: Between January 2010 and August 2015, 3953 N. gonorrhoeae isolates from both metropolitan and regional Queensland infections were typed with NG-MAST (N. gonorrhoeae multiantigen sequence typing) to assess the genetic diversity between strains. Whole-genome sequencing (WGS) was used to investigate strain-related factors associated with DGI. RESULTS: ST6876 was the most common NG-MAST type, detected in 7.6% of the isolates. DGI was significantly more likely in females <30 years (OR 13.02, p<0.0001) and in older males >30 years (OR 6.04, p<0.0001), with most cases originating from North Queensland (OR 8.5, p<0.0001). Strains harbouring PIA class of porB type were associated with DGI (OR 33.23, p<0.0001). CONCLUSION: Genotyping techniques, such as NG-MAST and WGS, are proving instrumental in providing an insight into the population structure of N. gonorrhoeae, and genetic mechanisms of pathogenesis, such as for DGI.

Outbreak of multi-drug-resistant (MDR) Shigella flexneri in northern Australia due to an endemic regional clone acquiring an IncFII plasmid.

Epidemiological surveillance of Shigella spp. in Australia is conducted to inform public health response. Multi-drug resistance has recently emerged as a contributing factor to sustained local transmission of Shigella spp. All data were collected as part of routine public health surveillance, and strains were whole-genome sequenced for further molecular characterisation. 108 patients with an endemic regional Shigella flexneri strain were identified between 2016 and 2019. The S. flexneri phylogroup 3 strain endemic to northern Australia acquired a multi-drug resistance conferring blaDHA plasmid, which has an IncFII plasmid backbone with virulence and resistance elements typically found in IncR plasmids. This is the first report of multi-drug resistance in Shigella sp. in Australia that is not associated with men who have sex with men. This strain caused an outbreak of multi-drug-resistant S. flexneri in northern Australia that disproportionality affects Aboriginal and Torres Strait Islander children. Community controlled public health action is recommended.

Genomic Characterization of Recent and Historic Meningococcal Serogroup E Invasive Disease in Australia: A Case Series.

We report the recent emergence of invasive meningococcal disease due to serogroup E in Queensland, Australia, in previously healthy patients. Molecular typing revealed the genotype of these strains to be E:P1.21-7,16:F5-36:ST-1157 (cc1157); when analyzed phylogenetically, compared with international cc1157 strains, they were relatively unrelated to each other.

Molecular Prediction of the O157:H-Negative Phenotype Prevalent in Australian Shiga Toxin-Producing Escherichia coli Cases Improves Concordance of In Silico Serotyping with Phenotypic Motility.

Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen, and serotype O157:H7 is typically associated with severe disease. Australia is unique in its STEC epidemiology, as severe cases are typically associated with non-O157 serogroups, and locally acquired O157 isolates are H-negative/nonmotile. The H-negative phenotype and reduced severity of disease compared to that associated with H7/motile strains are distinct features of Australian O157 strains, but the molecular mechanism behind this phenotype has not been reported. Accurate characterization of the H-negative phenotype is important in epidemiological surveillance of STEC. Serotyping is moving away from phenotype-based methods, as next generation sequencing allows rapid extrapolation of serotype through in silico detection of the O-antigen processing genes, wzx, wzy, wzm, and wzt, and the H-antigen gene, fliC The detection and genotyping of fliC alone is unable to determine the motility of the strain. Typically, most Australian O157:H-negative strains carry an H7 genotype yet phenotypically are nonmotile; thus, many are mischaracterized as H7 strains by in silico serotyping tools. Comparative genomic analysis of flagellar genes between Australian and international isolates was performed and an insertion at nucleotide (nt) 125 in the flgF gene was identified in H-negative isolates. Chi-square results showed that this insertion was significantly associated with the H-negative phenotype (P < 0.0001). Phylogenetic analysis was also completed and showed that the Australian H-negative isolates with the insertion in flgF represent a clade within the O157 serogroup, distinct from O157:H7 serotypes. This study provides a genetic target for inferring the nonmotile phenotype of Australian O157 STEC, which increases the predictive value of in silico serotyping.