Direct detection of markers associated with Neisseria gonorrhoeae antimicrobial resistance in New Zealand using residual DNA from the Cobas 4800 CT/NG NAAT assay.

OBJECTIVES: To use nucleic acid amplification techniques (NAAT) for detection of markers associated with gonococcal antimicrobial resistance (AMR) in non-cultured clinical samples to enhance surveillance of Neisseria gonorrhoeae AMR in New Zealand. METHODS: A total of 198 clinical samples from patients living in two cities, Wellington and Auckland and the more rural region of Gisborne, New Zealand, which were positive for N. gonorrhoeae by the Cobas 4800 were tested for three markers that predict reduced susceptibility or resistance to three antibiotics. Residual DNA extracts from the Cobas 4800 NG/CT test were tested for a single-nucleotide polymorphism in the gyrA gene at codon 91 associated with quinolone resistance; a sequence on the plasmid in penicillinase-producing N. gonorrhoeae (PPNG) which confers resistance to penicillin and the mosaic penA sequence associated with reduced susceptibility to extended-spectrum cephalosporins in N. gonorrhoeae. RESULTS: A total of 186/198 (94%) of the samples provided a valid result on gyrA genotyping, confirming the utility of N. gonorrhoeae DNA extracted by the Roche Cobas 4800 CT/NG test for subsequent detection of AMR markers. The NAAT results for Wellington, Auckland and Gisborne, respectively, showed that 77%, 33% and 32% of samples had the marker associated with quinolone resistance, while 4%, 15% and 0% were positive for the PPNG plasmid marker, and 9%, 5% and 0% samples were positive for mosaic penA sequence. CONCLUSIONS: The use of residual clinical DNA samples from the Cobas 4800 CT/NG test proved an efficient and effective method for performing AMR genotyping. These data also show for the first time the presence of gonococci with a mosaic penA sequence in New Zealand. Overall, the results further highlight the potential of molecular methods to aid N. gonorrhoeae AMR surveillance, particularly for regions where gonococcal culture is no longer performed.

Tracking oseltamivir-resistance in New Zealand influenza viruses during a medicine reclassification in 2007, a resistant-virus importation in 2008 and the 2009 pandemic.

INTRODUCTION: Oseltamivir (Tamiflu®) is an important pharmaceutical intervention against the influenza virus. The importance of surveillance for resistance to oseltamivir has been highlighted by two global events: the emergence of an oseltamivir-resistant seasonal influenza A(H1N1) virus in 2008, and emergence of the influenza A(H1N1)pdm09 virus in 2009. Oseltamivir is a prescription medicine in New Zealand, but more timely access has been provided since 2007 by allowing pharmacies to directly dispense oseltamivir to patients with influenza-like illness. OBJECTIVE: To determine the frequency of oseltamivir-resistance in the context of a medicine reclassification in 2007, the importation of an oseltamivir-resistant seasonal influenza virus in 2008, and the emergence of a pandemic in 2009. METHODS: A total of 1795 influenza viruses were tested for oseltamivir-resistance using a fluorometric neuraminidase inhibition assay. Viruses were collected as part of a sentinel influenza surveillance programme between the years 2006 and 2010. RESULTS: All influenza B, influenza A(H3N2) and influenza A(H1N1)pdm09 viruses tested between 2006 and 2010 were shown to be sensitive to oseltamivir. Seasonal influenza A(H1N1) viruses from 2008 and 2009 were resistant to oseltamivir. Sequencing of the neuraminidase gene showed that the resistant viruses contained an H275Y mutation, and S247N was also identified in the neuraminidase gene of one seasonal influenza A(H1N1) virus that exhibited enhanced resistance. DISCUSSION: No evidence was found to suggest that increased access to oseltamivir has promoted resistance. A probable importation event was documented for the global 2008 oseltamivir-resistant seasonal A(H1N1) virus nine months after it was first reported in Europe in January 2008.

Pandemic (H1N1) 2009 and seasonal influenza A (H1N1) co-infection, New Zealand, 2009.

Co-infection with seasonal influenza A (H1N1) and pandemic (H1N1) 2009 could result in reassortant viruses that may acquire new characteristics of transmission, virulence, and oseltamivir susceptibility. Results from oseltamivir-sensitivity testing on viral culture suggested the possibility of co-infections with oseltamivir-resistant (seasonal A [H1N1]) and -susceptible (pandemic [H1N1] 2009) viruses.