Improved paediatric antimicrobial prescribing with a smartphone application: a before and after interventional study.

INTRODUCTION: Children have a high consumption of antimicrobials that require complicated decision-making by prescribers. Despite this, antimicrobial stewardship (AMS) interventions are often not translated into paediatric medicine. Script is a smartphone application (app) launched in Auckland, New Zealand to support decision-making for antimicrobial prescribers. The aim was to improve adherence to existing local clinical guidelines for both adult and paediatric infections. METHODS: Inpatient and emergency department antimicrobial prescriptions were prospectively collected and evaluated for guideline adherence. Baseline prescribing data were collected and compared with prescribing at 4 months and 1 year after the app was launched. Prescriptions were graded as 'appropriate' or 'inappropriate' by investigators. Grading was done blinded to timing of the prescription relative to the intervention. RESULTS: Following the launch of the Script app, guideline adherence significantly increased from 241 of 348 (69%) antimicrobial prescriptions graded as appropriate during the baseline period to 301 of 359 (83%) after 4 months (p<0.0001). This improvement from baseline was sustained at 1 year with 263 of 323 (81%) adherence (p<0.001). At 1 year, this improvement could be demonstrated separately for medical, surgical and emergency department prescriptions. CONCLUSION: There was a significant and sustained improvement in adherence to paediatric antimicrobial guidelines following the introduction of a prescribing support app. The need to seek guidance for antimicrobial doses due to the age-based and weight-based calculations in paediatrics may mean that AMS interventions such as decision support and prescribing tools are particularly well suited to paediatric prescribing.

Long-Term Impact of a Smartphone App on Prescriber Adherence to Antibiotic Guidelines for Adult Patients With Community-Acquired Pneumonia: Interrupted Time-Series Study.

BACKGROUND: Mobile health platforms like smartphone apps that provide clinical guidelines are ubiquitous, yet their long-term impact on guideline adherence remains unclear. In 2016, an antibiotic guidelines app, called SCRIPT, was introduced in Auckland City Hospital, New Zealand, to provide local antibiotic guidelines to clinicians on their smartphones. OBJECTIVE: We aimed to assess whether the provision of antibiotic guidelines in a smartphone app resulted in sustained changes in antibiotic guideline adherence by prescribers. METHODS: We analyzed antibiotic guideline adherence rates during the first 24 hours of hospital admission in adults diagnosed with community-acquired pneumonia using an interrupted time-series study with 3 distinct periods post app implementation (ie, 3, 12, and 24 months). RESULTS: Adherence increased from 23% (46/200) at baseline to 31% (73/237) at 3 months and 34% (69/200) at 12 months, reducing to 31% (62/200) at 24 months post app implementation (P=.07 vs baseline). However, increased adherence was sustained in patients with pulmonary consolidation on x-ray (9/63, 14% at baseline; 23/77, 30% after 3 months; 32/92, 35% after 12 month; and 32/102, 31% after 24 months; P=.04 vs baseline). CONCLUSIONS: An antibiotic guidelines app increased overall adherence, but this was not sustained. In patients with pulmonary consolidation, the increased adherence was sustained.

An eight-plex immunoassay for Group A streptococcus serology and vaccine development.

Group A Streptococcus (GAS) is a major human pathogen responsible for superficial infections through to life-threatening invasive disease and the autoimmune sequelae acute rheumatic fever (ARF). Despite a significant global economic and health burden, there is no licensed vaccine available to prevent GAS disease. Several pre-clinical vaccines that target conserved GAS antigens are in development. Assays that measure antigen-specific antibodies are essential for vaccine research. The aim of this study was to develop a multiplex beadbased immunoassay that can detect and quantify antibody responses to multiple GAS antigen targets in small volume blood samples. This builds on our existing triplex assay comprised of antigens used in clinical serology for the diagnosis of ARF (SLO, DNase B and SpnA). Five additional conserved putative GAS vaccine antigens (Spy0843, SCPA, SpyCEP, SpyAD and the Group A carbohydrate), were coupled to spectrally unique beads to form an 8-plex antigen panel. After optimisation of the assay protocol, standard curves were generated, and assessments of assay specificity, precision and reproducibility were conducted. A broad range of antibody (IgG) titres were able to be quickly and accurately quantified from a single serum dilution. Assay utility was assessed using a panel of 62 clinical samples including serum from adults with GAS bacteraemia and children with ARF. Circulating IgG to all eight antigens was elevated in patients with GAS disease (n = 23) compared to age-matched controls (n = 39) (P < 0.05). The feasibility of using dried blood samples to quantify antigen-specific IgG was also demonstrated. In summary, a robust and reproducible 8-plex assay has been developed that simultaneously quantifies IgG antibodies to GAS vaccine and diagnostic antigens.

The Impact of the Auckland Cellulitis Pathway on Length of Hospital Stay, Mortality Readmission Rate, and Antibiotic Stewardship.

BACKGROUND: The Dundee classification of cellulitis severity, previously shown to predict disease outcomes, provides an opportunity to improve the management of patients with cellulitis. METHODS: We developed and implemented a pathway to guide the management of adults with cellulitis based on their Dundee severity class, and measured its effect on patient outcomes. We compared the outcomes in patients admitted to Auckland City Hospital (ACH) between July 2014 and July 2015 (the baseline cohort) with those in patients admitted between June 2017 and June 2018 (the intervention cohort). RESULTS: The median length of stay was shorter in the intervention cohort (0.7 days, interquartile range (IQR) 0.1 to 3.0 days) than in the baseline cohort (1.8 days, IQR 0.1 to 4.4 days; P < .001). The 30-day mortality rate declined from 1.8% (19/1092) in the baseline cohort to 0.7% (10/1362; P = .02) in the intervention cohort. The 30-day cellulitis readmission rate increased from 6% in the baseline cohort to 11% (P < .001) in the intervention cohort. Adherence to the ACH cellulitis antibiotic guideline improved from 38% to 48% (P < .01) and was independently associated with reduced length of stay. CONCLUSIONS: The implementation of the Auckland cellulitis pathway, readily generalizable to other settings, improved the outcomes in patients with cellulitis, and resulted in an annual saving of approximately 1000 bed days.

Collaborative networks enable the rapid establishment of serological assays for SARS-CoV-2 during nationwide lockdown in New Zealand.

BACKGROUND: Serological assays that detect antibodies to SARS-CoV-2 are critical for determining past infection and investigating immune responses in the COVID-19 pandemic. We established ELISA-based immunoassays using locally produced antigens when New Zealand went into a nationwide lockdown and the supply chain of diagnostic reagents was a widely held domestic concern. The relationship between serum antibody binding measured by ELISA and neutralising capacity was investigated using a surrogate viral neutralisation test (sVNT). METHODS: A pre-pandemic sera panel (n = 113), including respiratory infections with symptom overlap with COVID-19, was used to establish assay specificity. Sera from PCR­confirmed SARS-CoV-2 patients (n = 21), and PCR-negative patients with respiratory symptoms suggestive of COVID-19 (n = 82) that presented to the two largest hospitals in Auckland during the lockdown period were included. A two-step IgG ELISA based on the receptor binding domain (RBD) and spike protein was adapted to determine seropositivity, and neutralising antibodies that block the RBD/hACE­2 interaction were quantified by sVNT. RESULTS: The calculated cut-off (>0.2) in the two-step ELISA maximised specificity by classifying all pre-pandemic samples as negative. Sera from all PCR-confirmed COVID-19 patients were classified as seropositive by ELISA ≥7 days after symptom onset. There was 100% concordance between the two-step ELISA and the sVNT with all 7+ day sera from PCR­confirmed COVID-19 patients also classified as positive with respect to neutralising antibodies. Of the symptomatic PCR-negative cohort, one individual with notable travel history was classified as positive by two-step ELISA and sVNT, demonstrating the value of serology in detecting prior infection. CONCLUSIONS: These serological assays were established and assessed at a time when human activity was severely restricted in New Zealand. This was achieved by generous sharing of reagents and technical expertise by the international scientific community, and highly collaborative efforts of scientists and clinicians across the country. The assays have immediate utility in supporting clinical diagnostics, understanding transmission in high-risk cohorts and underpinning longer­term 'exit' strategies based on effective vaccines and therapeutics.

Genotypic and phenotypic analyses reveal distinct population structures and ecotypes for sugar beet-associated Pseudomonas in Oxford and Auckland.

Fluorescent pseudomonads represent one of the largest groups of bacteria inhabiting the surfaces of plants, but their genetic composition in planta is poorly understood. Here, we examined the population structure and diversity of fluorescent pseudomonads isolated from sugar beet grown at two geographic locations (Oxford, United Kingdom and Auckland, New Zealand). To seek evidence for niche adaptation, bacteria were sampled from three types of leaves (immature, mature, and senescent) and then characterized using a combination of genotypic and phenotypic analysis. We first performed multilocus sequence analysis (MLSA) of three housekeeping genes (gapA, gltA, and acnB) in a total of 152 isolates (96 from Oxford, 56 from Auckland). The concatenated sequences were grouped into 81 sequence types and 22 distinct operational taxonomic units (OTUs). Significant levels of recombination were detected, particularly for the Oxford isolates (rate of recombination to mutation (r/m) = 5.23 for the whole population). Subsequent ancestral analysis performed in STRUCTURE found evidence of six ancestral populations, and their distributions significantly differed between Oxford and Auckland. Next, their ability to grow on 95 carbon sources was assessed using the Biolog™ GN2 microtiter plates. A distance matrix was generated from the raw growth data (A 660) and subjected to multidimensional scaling (MDS) analysis. There was a significant correlation between substrate utilization profiles and MLSA genotypes. Both phenotypic and genotypic analyses indicated presence of a geographic structure for strains from Oxford and Auckland. Significant differences were also detected for MLSA genotypes between strains isolated from immature versus mature/senescent leaves. The fluorescent pseudomonads thus showed an ecotypic population structure, suggestive of adaptation to both geographic conditions and local plant niches.

The use of a poster to reduce expectations to receive antibiotics for a common cold.

Many doctors prescribe antibiotics for a cold, to meet patient's expectations. As a result, patient's education about antibiotics and antibiotic resistance forms a major component of the WHO's Global Action Plan on Antimicrobial Resistance. However, it is not known whether simple educational material can change a person's attitudes about antibiotic therapy. We designed three posters about antibiotic treatment for "cold and flu". Hospital inpatients answered a baseline survey and then were asked to look at one of three randomly selected posters. The posters highlighted the futility of antibiotic treatment for colds (futility), the risk of adverse drug reactions from antibiotics (harm), and the issue of antimicrobial resistance (resistance). Participants then completed a follow-up survey. Participants' expectations to receive antibiotics for a "bad cold" reduced significantly after viewing a poster (82/299, 27% expected antibiotics in the baseline survey compared with 13% in the follow-up survey, P < 0.01). Continuing expectation to receive antibiotics after viewing one of the posters was associated with expectation to receive antibiotics in the baseline survey and the strong belief that colds were caused by bacteria. Participants who viewed the resistance poster were more likely to continue to expect antibiotics than participants who viewed the futility poster (OR 2.46, 95%CI 1.16-5.20, P = 0.02). Following discussion of the study, viewing a poster reduced participants' expectations to receive antibiotics for a hypothetical cold. Changing patients' expectations to receive antibiotics using simple educational material about antibiotic futility could lead to significant reductions in antibiotic prescription for viral upper respiratory tract infections.

Impact of a smartphone app on prescriber adherence to antibiotic guidelines in adult patients with community acquired pneumonia or urinary tract infections.

BACKGROUND: Mobile phone apps have been shown to enhance guideline adherence by prescribers, but have not been widely evaluated for their impact on guideline adherence by prescribers caring for inpatients with infections. OBJECTIVES: To determine whether providing the Auckland City Hospital (ACH) antibiotic guidelines in a mobile phone app increased guideline adherence by prescribers caring for inpatients with community acquired pneumonia (CAP) or urinary tract infections (UTIs). METHODS: We audited antibiotic prescribing during the first 24 hours after hospital admission in adults admitted during a baseline and an intervention period to determine whether provision of the app increased the level of guideline adherence. To control for changes in prescriber adherence arising from other factors, we performed similar audits of adherence to antibiotic guidelines in two adjacent hospitals. RESULTS: The app was downloaded by 145 healthcare workers and accessed a total of 3985 times during the three month intervention period. There was an increase in adherence to the ACH antibiotic guidelines by prescribers caring for patients with CAP from 19% (37/199) to 27% (64/237) in the intervention period (p = 0.04); but no change in guideline adherence at an adjacent hospital. There was no change in adherence to the antibiotic guidelines by prescribers caring for patients with UTI at ACH or at the two adjacent hospitals. CONCLUSIONS: Provision of antibiotic guidelines in a mobile phone app can significantly increase guideline adherence by prescribers. However, providing an app which allows easy access to antibiotic guidelines is not sufficient to achieve high levels of prescriber adherence.

Efficacy and acceptability of treatment to eradicate nasal Staphylococcus aureus carriage among haemodialysis patients.

AIM: For patients requiring haemodialysis, the risk of Staphylococcus aureus disease is higher in those colonized and persists while the person requires haemodialysis, necessitating frequent decolonization. However, the duration of successful decolonization is not known. This study aimed to determine the duration of efficacy of decolonization in intermittent and persistent S. aureus carriers requiring haemodialysis using two decolonization strategies. METHODS: We screened 100 outpatients requiring haemodialysis for S. aureus carriage and then decolonized 14 intermittent carriers and 18 persistent carriers. Participants were invited to undertake two decolonization attempts, using systemic or topical antibiotics 12 weeks apart. Nasal swabs were taken weekly to determine the duration of successful decolonization. RESULTS: Decolonization was successful in 24/32 (75%) participants and the median duration of decolonization was 35 days (95% confidence interval (CI) 11-59). The median duration of S. aureus decolonization was significantly shorter for persistent carriers (19 days, 95% CI 13-25 days) in comparison with intermittent carriers (70 days, 95% CI 61-79 days; P < 0.01). 28/52 (54%) post-decolonization surveys indicated that they would use the treatment again, 14/52 (27%) surveys indicated that they would not use the treatment again, and 10/52 (19%) were undecided. 16/53 (30%) decolonization attempts resulted in an adverse drug reaction. CONCLUSION: Staphylococcus aureus decolonization using topical or systemic treatments was successful for many haemodialysis patients, and provided a month free of S. aureus colonization. Although decolonization treatment provided a shorter duration of success for persistent carriers in comparison with intermittent carriers, persistent carriers are likely to gain the most from effective decolonization strategies.

Association of the Dundee severity classification with mortality, length of stay and readmission in adult inpatients with cellulitis.

Background: The Dundee classification is a simple severity assessment tool that could optimize treatment decisions and clinical outcomes in adult patients with cellulitis; however, it has not been validated in a large cohort. Objectives: To determine whether the Dundee classification reliably identified those patients with cellulitis who had a higher mortality, a longer length of hospital stay or an increased risk of readmission. Methods: We performed a retrospective study of all adults with a primary discharge diagnosis of cellulitis admitted to Auckland City Hospital from August 2013 to June 2015. We classified patients by severity using the Dundee scoring system. Results: The 30 day all-cause mortality in adult patients with a discharge diagnosis of cellulitis was 2% (29/1462) overall, and was 1% (10/806), 2% (6/271), 3% (10/353) and 9% (3/32) in Classes 1, 2, 3 and 4 of the Dundee classification, respectively (P = 0.01). Mortality was strongly associated with age >65 years (OR 9.37, 95% CI 3.00-41.23) and with heart failure (OR 6.16, 95% CI 2.73-14.23). There were significant associations between the Dundee classification and the incidence of bacteraemia, the length of hospital stay and the rate of readmission to hospital. Conclusions: The Dundee classification is a simple, reliable tool that can be easily applied in clinical settings to predict risk of mortality in order to determine which patients can be managed in the community with oral or intravenous therapy, and which require inpatient care.

Staphylococcus aureus colonisation and its relationship with skin and soft tissue infection in New Zealand children.

New Zealand children suffer from high rates of skin and soft tissue infection (SSTI). Staphylococcus aureus colonisation is known to increase the risk of nosocomial infection. We aimed to determine whether S. aureus colonisation also increased the risk of community-onset SSTI. This study, performed within the Growing Up in New Zealand cohort, used interview and administrative data, and bacterial culture results from the nose, throat, and skin swabs collected at 4½ years of age. Multivariable log-binomial regression was used to derive adjusted risk ratios. S. aureus was isolated from 2225/5126 (43.4%) children. SSTI affected 1509/5126 (29.4%) children before age five. S. aureus colonisation at any site was associated with SSTI (aRR = 1.09, 95%CI 1.01-1.19), particularly in the year prior to swab collection (aRR = 1.18, 95%CI 1.02-1.37). The strongest association was between skin colonisation and SSTI within the year prior to swab collection (aRR = 1.47, 95%CI 1.14-1.84). Socioeconomic and ethnic variables remained independent determinants of SSTI. S. aureus colonisation was associated with an increased risk of community-onset SSTI. Socioeconomic and ethnic factors and eczema had independent effects on SSTI risk. Interventions which reduce the prevalence of S. aureus colonisation may be expected to reduce the incidence of community-onset SSTI.

Artificial Urine for Teaching Urinalysis Concepts and Diagnosis of Urinary Tract Infection in the Medical Microbiology Laboratory.

Dipstick urinalysis is an informative, quick, cost-effective and non-invasive diagnostic tool that is useful in clinical practice for the diagnosis of urinary tract infections (UTIs), kidney diseases, and diabetes. We used dipstick urinalysis as a hands-on microbiology laboratory exercise to reinforce student learning about UTIs with a particular focus on cystitis, which is a common bacterial infection. To avoid exposure to potentially contaminated human urine samples, we prepared artificial urine using easily acquired and affordable ingredients, which allowed less-experienced students to perform urinalysis without the risk of exposure to pathogenic organisms and ensured reliable availability of the urine samples. This practical class taught medical students how to use urinalysis data in conjunction with medical history to diagnose diseases from urine samples and to determine a treatment plan for clinical scenarios.

Previous antibiotic-related adverse drug reactions do not reduce expectations for antibiotic treatment of upper respiratory tract infections.

BACKGROUND: Patients' expectations may influence prescribers' decisions about antibiotic prescribing for upper respiratory tract infection (URTI). We examined whether a history of an antibiotic related adverse drug reaction (aADR) influenced a person's perception about the safety of antibiotics or their expectation of receiving an antibiotic prescription for an URTI. METHODS: We developed a questionnaire and surveyed 103 hospital inpatients, 38 of whom (37%) reported past experience of aADR. RESULTS: Of the 88 participants who reported recent antibiotic use, participants with a history of aADR reported increased perception of harm from their last antibiotic treatment (P<0.05). Overall, 41/103 (40%) participants expected their doctors to prescribe antibiotics to treat an URTI. Participants' perceptions of antibiotic safety or expectation of antibiotic treatment for an URTI did not differ between those who had personal experience of an aADR compared with those with no history of aADR. CONCLUSIONS: The almost universal belief that antibiotics are safe, beneficial medications, even among people with prior aADR, helps to explain the strong patient expectations for antibiotic treatment in a range of conditions. Educational campaigns about the prescription of antibiotics for viral URTI should include information that the risk of harm far outweighs any potential benefits.

Antibiotic consumption by New Zealand children: exposure is near universal by the age of 5 years.

Background: Increasing concerns about antibiotic resistance and microbiome disruption have stimulated interest in describing antibiotic consumption in young children. Young children are an age group for whom antibiotics are frequently prescribed. Objectives: To describe community antibiotic dispensing during the first 5 years of life in a large, socioeconomically and ethnically diverse cohort of children, and to determine how antibiotic dispensing varied between population subgroups. Methods: This study was performed within the Growing Up in New Zealand longitudinal cohort study ( www.growingup.co.nz ) with linkage to national administrative antibiotic dispensing data. Descriptive statistics and univariate and multivariable associations were determined. Results: The 5581 cohort children received 53 052 antibiotic courses, of which 54% were amoxicillin. By age 5 years, 97% of children had received one or more antibiotic courses, and each child had received a median of eight antibiotic courses (IQR 4-13). The mean incidence of antibiotic dispensing was 1.9 courses/child/year. Multivariable negative binomial regression showed that Maori and Pacific children received more antibiotic courses than European children, as did children in the most-deprived compared with the least-deprived areas. A distinct seasonal pattern was noted. Conclusions: This study provided a detailed description of antibiotic dispensing within a large and diverse child cohort. Antibiotic exposure was near universal by age 5 years. The predominance of amoxicillin use and the seasonal pattern suggest much antibiotic use may have been for self-limiting respiratory infections. There is a need for safe and effective interventions to improve antibiotic prescribing practices for New Zealand children.

Ethnic disparities in infectious disease hospitalisations in the first year of life in New Zealand.

AIM: Infectious disease (ID) hospitalisation rates are increasing in New Zealand (NZ), especially in pre-school children, and Maori and Pacific people. We aimed to identify risk factors for ID hospitalisation in infancy within a birth cohort of NZ children, and to identify differences in risk factors between ethnic groups. METHODS: We investigated an established cohort of 6846 NZ children, born in 2009-2010, with linkage to a national data set of hospitalisations. We used multivariable logistic regression to obtain odds ratios (OR) for factors associated with ID hospitalisation in the first year of life, firstly for all children, and then separately for Maori or Pacific children. RESULTS: In the whole cohort, factors associated with ID hospitalisation were Maori (OR: 1.49, 95% CI: 1.17-1.89) or Pacific (2.51; 2.00-3.15) versus European maternal ethnicity, male gender (1.32; 1.13-1.55), low birthweight (1.94, 1.39-2.66), exclusive breastfeeding for <4 months (1.22, 1.04-1.43), maternal experience of health-care racism (1.60, 1.19-2.12), household deprivation (most vs. least deprived quintile of households (1.50, 1.12-2.02)), day-care attendance (1.43, 1.12-1.81) and maternal smoking (1.55, 1.26-1.91). Factors associated with ID hospitalisation for Maori infants were high household deprivation (2.16, 1.06-5.02) and maternal smoking (1.48, 1.02-2.14); and for Pacific infants were delayed immunisation (1.72, 1.23-2.38), maternal experience of health-care racism (2.20, 1.29-3.70) and maternal smoking (1.59, 1.10-2.29). CONCLUSIONS: Maori and Pacific children in NZ experience a high burden of ID hospitalisation. Some risk factors, for example maternal smoking, are shared, while others are ethnic-specific. Interventions aimed at preventing ID hospitalisations should address both shared and ethnic-specific factors.

Rapid Emergence and Evolution of Staphylococcus aureus Clones Harboring fusC-Containing Staphylococcal Cassette Chromosome Elements.

The prevalence of fusidic acid (FA) resistance amongStaphylococcus aureusstrains in New Zealand (NZ) is among the highest reported globally, with a recent study describing a resistance rate of approximately 28%. Three FA-resistantS. aureusclones (ST5 MRSA, ST1 MSSA, and ST1 MRSA) have emerged over the past decade and now predominate in NZ, and in all three clones FA resistance is mediated by thefusCgene. In particular, ST5 MRSA has rapidly become the dominant MRSA clone in NZ, although the origin of FA-resistant ST5 MRSA has not been explored, and the genetic context offusCin FA-resistant NZ isolates is unknown. To better understand the rapid emergence of FA-resistantS. aureus, we used population-based comparative genomics to characterize a collection of FA-resistant and FA-susceptible isolates from NZ. FA-resistant NZ ST5 MRSA displayed minimal genetic diversity and represented a phylogenetically distinct clade within a global population model of clonal complex 5 (CC5)S. aureus In all lineages,fusCwas invariably located within staphylococcal cassette chromosome (SCC) elements, suggesting that SCC-mediated horizontal transfer is the primary mechanism offusCdissemination. The genotypic association offusCwithmecAhas important implications for the emergence of MRSA clones in populations with high usage of fusidic acid. In addition, we found thatfusCwas colocated with a recently described virulence factor (tirS) in dominant NZS. aureusclones, suggesting a fitness advantage. This study points to the likely molecular mechanisms responsible for the successful emergence and spread of FA-resistantS. aureus.

A bug in the ointment: topical antimicrobial usage and resistance in New Zealand.

New Zealand has unenviably high rates of bacterial resistance to topical antimicrobials. In this Viewpoint, we review the history and usage of topical antimicrobials in New Zealand, and suggest some strategies to mitigate further increases in antimicrobial resistance to topical agents.

High usage of topical fusidic acid and rapid clonal expansion of fusidic acid-resistant Staphylococcus aureus: a cautionary tale.

Our aim was to assess national prescribing trends and determine longitudinal resistance patterns for topical antimicrobials in New Zealand. We observed a dramatic increase in fusidic acid (FA) resistance, and clonal expansion of FA-resistant Staphylococcus aureus. This increase was concurrent with a significant national increase in topical FA dispensing.

The genetic structure of Staphylococcus aureus populations from the Southwest Pacific.

The genetic structure of Staphylococcus aureus populations sampled from diverse regions of the globe have been the subject of numerous investigations. Here we describe the structure of S. aureus populations collected from the Southwest Pacific. Multi-locus sequence typing was performed on 467 isolates obtained from people with nasal colonization or bacteremia in Auckland (NZ), and patients predominantly affected by skin and soft tissue infection in Samoa, Fiji and Tonga. The predominant sequence types (STs) varied between Auckland (ST5), Fiji (ST30), and Samoa (ST1), however, the overall genetic diversity within each region did not differ significantly between locations. Divergent Clonal Complex 75 (CC75) strains were isolated in Auckland and Fiji. When diversity of the Southwest Pacific populations was compared with those previously described from Asia, Europe, North America and Africa no significant differences were detected. With the exception of CC75 strains, the global collection of S. aureus encompasses relatively little diversity, with novel STs arising locally from a small number of widespread lineages.