Browsing by Author "Dyet K"

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    20 years later: unravelling the genomic success of New Zealand’s home-grown AK3 community-associated methicillin-resistant Staphylococcus aureus
    (Microbiology Society, 2025-07-25) White RT; Bakker S; Bloomfield M; Burton M; Elvy J; Eustace A; French NP; Grant J; Greening SS; Grinberg A; Harland C; Hutton S; Karkaba A; Martin J; Matthews B; Miller H; Straub C; Tarring C; Taylor WT; Ussher J; Velasco C; Voss EM; Dyet K
    Methicillin-resistant Staphylococcus aureus (MRSA) represents a significant public health challenge. In New Zealand, the community-associated MRSA sequence type (ST)5, carrying the staphylococcal cassette chromosome mec (SCCmec) type IV genetic element (which confers methicillin resistance), has been predominant since its detection in 2005. Known informally as the AK3 strain, it also exhibits resistance to fusidic acid. Here, we investigated the genomic evolution of the AK3 strain by analysing 397 genomes, comprising 361 MRSA and 36 closely related methicillin-susceptible S. aureus (MSSA) genomes, including 285 recently sequenced isolates from New Zealand spanning 2020 (n=30), 2021 (n=77), 2022 (n=88), 2023 (n=73) and 2024 (n=17). Phylogenetic analysis revealed that the AK3 strain evolved through stepwise acquisition of mobile genetic elements, with an MSSA ancestor likely introduced to New Zealand in the late 1970s. The lineage first acquired a SaPITokyo12571-like pathogenicity island, which contains the staphylococcal enterotoxin C bovine variant (sec-bov) and an enterotoxin-like protein (sel), between 1984 and 1991. This was followed by the integration of SCCmec type IV and adjacent fusidic acid resistance operon between 1997 and 2000. This timing coincides with increased community fusidic acid use in New Zealand. The AK3 strain then diversified into three major clades, spreading throughout New Zealand and Australia, with sporadic detection in European countries and Samoa. Our findings demonstrate how the sequential acquisition of mobile genetic elements, combined with antibiotic selection pressure, likely contributed to the successful emergence of AK3 and its spread in the South Pacific region.
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    Antimicrobial Resistance in New Zealand—A One Health Perspective
    (1/06/2022) Pattis I; Weaver L; Burgess S; Ussher JE; Dyet K
    Antimicrobial resistance (AMR) is an increasing global threat that affects human, animal and, often less acknowledged, environmental health. This complex issue requires a multisectoral One Health approach to address the interconnectedness of humans, animals and the natural environment. The prevalence of AMR in these reservoirs varies widely among countries and thus often requires a country-specific approach. In New Zealand (NZ), AMR and antimicrobial usage in humans are relatively well-monitored and-understood, with high human use of antimicrobials and the frequency of resistant pathogens increasing in hospitals and the community. In contrast, on average, NZ is a low user of antimicrobials in animal husbandry systems with low rates of AMR in food-producing animals. AMR in New Zealand’s environment is little understood, and the role of the natural environment in AMR transmission is unclear. Here, we aimed to provide a summary of the current knowledge on AMR in NZ, addressing all three components of the One Health triad with a particular focus on environmental AMR. We aimed to identify knowledge gaps to help develop research strategies, especially towards mitigating AMR in the environment, the often-neglected part of the One Health triad.
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    Preparing for the next pandemic: insights from Aotearoa New Zealand's Covid-19 response
    (Elsevier Ltd, 2025-03-18) French NP; Maxwell H; Baker MG; Callaghan F; Dyet K; Geoghegan JL; Hayman DTS; Huang QS; Kvalsvig A; Russell E; Scott P; Thompson TP; Plank MJ
    In 2020 Aotearoa New Zealand, like many other countries, faced the coronavirus pandemic armed with an influenza-based pandemic plan. The country adapted rapidly to mount a highly strategic and effective elimination response to the SARS-CoV-2 pandemic. However, implementation was hampered by gaps in pandemic preparedness. These gaps undermined effectiveness of the response and exacerbated inequitable impacts of both Covid-19 disease and control measures. Our review examines the Covid-19 response, reflecting on strengths, limitations and implications for pandemic planning. We identify three key areas for improvement: 1) development of a systematised procedure for risk assessment of a new pandemic pathogen; 2) investment in essential capabilities during inter-pandemic periods; and 3) building equity into all stages of the response. We present a typology of potential pathogens and scenarios and describe the evidence assessment process and core capabilities required for countries to respond fluidly, equitably, and effectively to a rapidly emerging pandemic threat.