Incidence of community onset MRSA in Australia: least reported where it is Most prevalent

Bloodstream infections and multidrug resistant bacteria acquisition among burns patients in Australia and New Zealand: A registry-based study

INTRODUCTION

This study interrogates infection related data in the Burns Registry of Australia and New Zealand (BRANZ), to examine associations of multi-drug resistant organisms (MDROs) and blood stream infection (BSI).

METHODS

Data between July 2016 and June 2021 were analysed to determine prevalence, risk factors and outcomes associated with BSIs and MDROs: Methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), carbapenem-resistant Pseudomonas spp. (CRP), and carbapenem-resistant Enterobacter (CRE). Data completeness and value for quality improvement activity were assessed.

RESULTS

We found a low incidence (3.4%) of the resistant organisms of interest, and no change over the study period. Fequency varied between services and increased with age and size of burn. MRSA was the commonest organism in all age groups. A positive BSI result occurred in 1.6% of patients (12.1% of cultures taken) at a median time of 10.2 days post injury. Free text identification of organisms was inconsistently documented.

CONCLUSIONS

The low rate and patterns of acquisition of MDROs of interest and BSIs is comparable with reports from countries with low incidence of massive burns. Wider adoption of a standardized laboratory reporting framework would help realise the potential of clinical quality registries to provide data which supports evidence based infection prevention initiatives.

Trends in clinical management of lactational mastitis among women attending Australian general practice: a national longitudinal study using MedicineInsight, 2011-2022

OBJECTIVE

To examine longitudinal trends in clinical management of lactational mastitis in women attending general practice.

DESIGN

Open cohort study.

SETTING

Australian general practice using data from MedicineInsight.

PARTICIPANTS

Women aged 18 to 44 years with one or more clinical encounters for lactational mastitis between January 2011 and July 2022.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measure was the proportion of prescribed oral antibiotics based on the antibiotic type. Secondary outcome measures were the proportion of women prescribed other medications (eg, antifungals, lactation suppressants) or ordered selected clinical investigations including breast ultrasound, blood test, breast milk culture, nipple swab culture or breast aspirate. Outcomes were examined based on the calendar year and individual- or clinical practice-level characteristics.

RESULTS

Among 25 002 women who had one or more clinical encounters related to mastitis, 90.9% were prescribed oral antibiotics. While the proportion of women prescribed an oral antibiotic remained consistent from 2011 to 2022 (91.1% vs 92.5%), there were changes in the proportion receiving prescriptions for di/flucloxacillin (46.1% vs 60.4%) and cefalexin (38.6% vs 26.5%). Fewer than 12% of women were clinically investigated for their mastitis encounter, most commonly a breast ultrasound (7.1%), followed by a selected blood test (3.8%). Requests for breast milk cultures, nipple swab cultures or breast aspirates occurred in less than 1.1% of individuals. Significant increases were evident with respect to ordering of all clinical investigations, with rates at least doubling between 2011 and 2022 (6.6% vs 14.7%). Large variability in clinical management was evident according to both individual- (eg, concessional status) and clinical practice-level characteristics (eg, remoteness).

CONCLUSIONS

Australian general practitioners commonly prescribe oral antibiotics to women with mastitis and largely in line with clinical guidelines. Their use of clinical investigations as part of mastitis management has increased over the last decade.

General practitioners' management of mastitis in breastfeeding women: a mixed method study in Australia

BACKGROUND

Mastitis is a common reason new mothers visit their general practitioner (GP). In Australia, the Therapeutic Guidelines: Antibiotic provides practical advice to GPs managing a range of infections, including mastitis. It is not known if Australian GPs prescribe antibiotics and order investigations as recommended for the management of mastitis.

METHODS

A convergent mixed methods design integrated quantitative analysis of a general practice dataset with analysis of interviews with GPs. Using the large-scale primary care dataset, MedicineInsight, (2021-2022), antibiotics prescribed and investigations ordered for mastitis encounters were extracted. Mastitis encounters were identified by searching 'Encounter reason', 'Test reason' and 'Prescription reason' free text field for the term 'mastitis'; 'granulomatous mastitis' was excluded. Clinical encounters for mastitis occurring within 14 days of a previous mastitis encounter were defined as belonging to the same treatment episode. Semi-structured interviews were conducted with 14 Australian GPs using Zoom or telephone in 2021-2022, and analysed thematically. The Pillar Integration Process was used to develop a joint display table; qualitative codes and themes were matched with the quantitative items to illustrate similarities/contrasts in findings.

RESULTS

During an encounter for mastitis, 3122 (91.7%) women received a prescription for an oral antibiotic; most commonly di/flucloxacillin ([59.4%]) or cefalexin (937 [27.5%]). Investigations recorded ultrasound in 303 (8.9%), blood tests (full blood examination [FBE]: 170 [5.0%]; C-reactive protein [CRP]: 71 [2.1%]; erythrocyte sedimentation rate [ESR]: 34 [1.0%]) and breast milk or nipple swab cultures in approximately 1% of encounters. Analysis using pillar integration showed consistency between quantitative and qualitative data regarding mastitis management. The following themes were identified: - GPs support continued breastfeeding. - Antibiotics are central to GPs' management. - Antibiotics are mostly prescribed according to Therapeutic Guidelines. - Analgesia is a gap in the Therapeutic Guidelines. - Low use of breast milk culture.

CONCLUSIONS

Prescribing antibiotics for mastitis remains central to Australian GPs' management of mastitis. Interview data clarified that GPs were aware that antibiotics might not be needed in all cases of mastitis and that delayed prescribing was not uncommon. Overall, GPs followed principles of antibiotic stewardship, however there is a need to train GPs about when to consider ordering investigations.

Is tropical pus in the hand special? A retrospective study comparing hand infection cases in Darwin and Adelaide

BACKGROUND

Hand infections are a common reason for presenting to hospital and can be associated with significant morbidity and prolonged antibiotic use. Factors recognized to influence patient outcomes include resistant organisms and delayed presentation. Surgeons working around Australia may assume that hand infections and appropriate treatment algorithms will be similar between sites. This is the first study to examine differences between hand infections presenting in Darwin (with its tropical climate) vs. those in a more temperate city (Adelaide).

METHODS

This is a two-site retrospective study, where diagnostic discharge codes were used to identify cases for a 12-month period and patient age, sex and rurality, duration of hospital stay, microbiology results and subsequent trips to theatre were reviewed.

RESULTS

Despite significant differences in rurality between FMC and RDH patients, there was no significant difference in length of hospital stay, duration of intravenous antibiotics or return trips to theatre across the two sites. RDH reported a 25% rate of MRSA, compared to 18% at FMC, as well as a statistically significant increase in uncommon microbes, with 30% compared to 12% of patients growing microbes that may not be covered by antibiotics routinely administered in metropolitan areas. A limitation of this study was that compliance with antibiotics and hospital stay were not accounted for.

CONCLUSION

It is often our training years that determine our norms of everyday practice, but fewer Australian surgical training posts are located in tropical centres. The results of this study highlight the importance of not assuming that the spectrum of organisms causing hand infections are the same as that in the surgeons' state of origin.

The antibacterial effectiveness of lavender essential oil against methicillin-resistant Staphylococcus aureus: a systematic review

With the overuse and misuse of antibiotics, multi-drug resistant organisms have become a prominent issue in healthcare, increasing morbidity and mortality in affected patients. One such organism of concern is methicillin-resistant Staphylococcus aureus (MRSA) which is a leading cause of a variety of clinical infections. Therefore, in the interest of finding alternate substances to antibiotics, there has been increased interest in the antibacterial properties of lavender essential oil (LEO). This systematic review aims to collate information regarding the antibacterial properties of LEO against S. aureus and MRSA. A systematic search was conducted across four databases between the years 2002 and 2022, and through this, 23 studies were included in this paper. These studies used a variety of methods to ascertain the antibacterial effectiveness of LEO alone or in combination with other substances. Overall, there were mixed results regarding the antibacterial effectiveness of LEO against S. aureus and MRSA, with some studies reporting significant effectiveness, while other studies reporting a minimal to negligible effect. However, findings suggest that LEO works synergistically with other antibacterial substances, and it would be beneficial for additional research to be conducted in this area.

Community antibiotic management of skin infections in the Torres Strait

BACKGROUND

There is a high burden of skin and soft tissue infections (SSTI) - including cellulitis - among Aboriginal and Torres Strait Islander peoples living in remote communities. In tropical environments, such as the Torres Strait, cellulitis accounts for 37% of potentially preventable hospitalisations. This study aimed to evaluate the safety, effectiveness and community acceptance of outpatient antibiotic treatment for the management of skin infections in the Torres Strait.

CONCLUSIONS

Outpatient management of skin infection in the Torres Strait is effective, safe and appreciated by patients.

METHODS

This was a 12-month prospective, observational study commencing in January 2019 involving 295 adults with a skin infection across the Torres Strait.

RESULTS

Most (276/295 (94%)) participants were treated successfully in the community. Of 295 enrolled patients, 151 of 295 (51%) had cellulitis, 59 of 295 (20%) had a skin abscess and 85 of 295 (28%) had a wound infection. Of the 77 of 278 (27%) infections accompanied by systemic features, 63 of 77 (82%) were managed in the community. Staphylococcus aureus was the most frequent isolate, at 165 of 261 (63%); 56 of 165 (33%) were methicillin resistant. In the 276 community-managed cases, oral trimethoprim/sulfamethoxazole was initially used in 159 (57%), oral flucloxacillin in 75 (27%) and intravenous cefazolin plus oral probenecid in 32 (13%). The clinical course was complicated in eight of 232 (3%) patients who had complete follow-up data: seven patients required hospitalisation after initial treatment in the communityand one had an antibiotic side-effect. All 232 patients with complete follow-up data were content with the care they received.

The same but different: a comparison of Staphylococcus aureus bloodstream infections in metropolitan and non-metropolitan hospitals (2010-2020)

BACKGROUND

Variation of infection rates between hospitals must be identified; differences may highlight opportunities for quality improvement in healthcare delivery to specific hospitals groups.

AIMS

To analyse burden, time trends and risks of healthcare-associated (HA) Staphylococcus aureus bloodstream infections (SABSI) in patients admitted to Victorian metropolitan and non-metropolitan public acute care hospitals.

METHODS

SABSI surveillance data submitted between 1 July 2010 and 30 June 2020 by all 118 Victorian public acute care hospitals were analysed. Aligned with the Australian Statistical Geography Standard Remoteness Structure, these hospitals were classified as metropolitan (major cities) or non-metropolitan (inner regional, outer regional, remote or very remote).

RESULTS

Most SABSI were community associated: 66.9% and 75.0% of metropolitan (n = 9441) and non-metropolitan (n = 2756) hospital SABSI respectively. The overall HA-SABSI rate was statistically higher in metropolitan hospitals (1.13 per 10 000 occupied bed days (OBD)) compared with non-metropolitan hospitals (0.82 per 10 000 OBD; P < 0.001). In metropolitan and non-metropolitan hospitals, there was a statistically significant decline in the overall HA-SABSI rate (incidence rate ratio = 0.96; 95% confidence interval: 0.95-0.97; P < 0.001; and incidence rate ratio = 0.98; 95% confidence interval: 0.97-1.00; P = 0.044, respectively). In metropolitan and non-metropolitan hospitals, HA-SABSI were frequently associated with central venous (52.8%) and peripheral intravenous (62.2%) catheter use respectively.

CONCLUSION

To reduce risks for SABSI and improve patient outcomes, hospital infection prevention and control programmes should be tailored according to local epidemiology. In common geographic locations, networking of hospitals should be considered as a means of strengthening delivery of these programmes.

Vancomycin Resistance in Enterococcus and Staphylococcus aureus

Enterococcus faecalis, Enterococcus faecium and Staphylococcus aureus are both common commensals and major opportunistic human pathogens. In recent decades, these bacteria have acquired broad resistance to several major classes of antibiotics, including commonly employed glycopeptides. Exemplified by resistance to vancomycin, glycopeptide resistance is mediated through intrinsic gene mutations, and/or transferrable van resistance gene cassette-carrying mobile genetic elements. Here, this review will discuss the epidemiology of vancomycin-resistant Enterococcus and S. aureus in healthcare, community, and agricultural settings, explore vancomycin resistance in the context of van and non-van mediated resistance development and provide insights into alternative therapeutic approaches aimed at treating drug-resistant Enterococcus and S. aureus infections.

Alhoot M, Abdul Karim S. Multidrug-Resistant Staphylococcus aureus as Coloniser in Healthy Individuals

Staphylococcus aureus is a common human pathogen that can cause mild superficial infections to deep-seated abscesses and sepsis. One of the characteristics of S. aureus is the ability to colonise healthy individuals while leaving them asymptomatic. These carriers’ risk harbouring an antibiotic-resistant strain that may be harmful to the individual and the community. S. aureus carriage in healthcare personnel is being studied extensively in many parts of the world. However, the relationship between colonisation and disease among those with no previous exposure to healthcare remains untouched. Colonisation of the nasal cavity and its surrounding by pathogenic organisms such as S. aureus leads to the increased risk of infection. Hospital-acquired infections associated with S. aureus infections are common and studies related to these types of infections among various study groups are largely documented. However, over the last decade, an increase in community-associated methicillin-resistant S. aureus has been noted, increasing the need to identify the prevalence of the organism among healthy individuals and assessing the antibiotic resistance patterns. Systemic surveillance of the community for colonisation of S. aureus and identifying the antibiotic-resistant pattern is critical to determine the appropriate empiric antibiotic treatment.

A fusidic acid-resistant (PVL+) clone is associated with the increase in methicillin-resistant Staphylococcus aureus in New Caledonia

OBJECTIVES

Since 2014, Staphylococcus aureus methicillin resistance is rapidly increasing in New Caledonia and is associated with potential serious clinical repercussions. In the present study, we investigated the epidemiology of Methicillin-Resistant S. aureus (MRSA) in New Caledonia and the possible emergence of a particular clonal strain.

METHODS

An overview of the distribution of MRSA in New Caledonia in 2019 is presented. We collected and analysed 171 clinical MRSA isolates from New Caledonia medical laboratories during August and September 2019. Among this collection, 49 representative isolates were analyzed by the French National Reference Center for Staphylococci using StaphyType DNA microarray allowing genetic characterization of the isolates.

RESULTS

Among the 1144 S. aureus isolated over the year 2019, 442 isolates (39%) were resistant to methicillin and 62% of these isolates were resistant to fusidic acid (FA). During the inclusion period, FA resistance rate was similar (60%). Genetic characterization evidenced CC6 as the predominant clonal complex (70%) with 26 isolates (53%) identified as CC6-MRSA-[IV+fus] (PVL+).

CONCLUSIONS

These findings demonstrated a low diversity of MRSA in New Caledonia with the dominance of a clonal complex not reported previously. The frequent fusidic acid (FA) resistance in MRSA was associated with a high prevalence of fusC, suggesting that FA misuse contributed to driving the selection of this clone. Our findings suggest the recommendation to stop the topical use of FA to control the emergence of this severe MRSA clone and decrease the rate of MRSA in New Caledonia.

Genomic Characterisation of CC398 MRSA Causing Severe Disease in Australia

Complex (CC) 398 livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) has been reported worldwide in a variety of food-animal species. Although CC398 is synonymous with LA-MRSA, community-associated MRSA (CA-MRSA) variants have emerged, including the Panton-Valentine leukocidin (PVL)-positive ST398-V and ST398 single locus variant ST1232-V, and the PVL-negative ST398-V clones. Using comparative genomic analysis, we determined if ten CC398 MRSA bacteraemia episodes recently identified in Australia were due to LA-MRSA or CA-MRSA CC398. The isolates were sourced from the Australian Group on Antimicrobial Resistance S. aureus surveillance program and episodes occurred across Australia Whole genome sequencing and phylogenetic comparison of the ten CC398 bacteraemia isolates with previously published CC398 MRSA whole-genome sequences identified the Australian CC398 isolates were closely related to the human-associated II-GOI clade, and the livestock-associated IIa clade. The identified CC398 MRSA clones were: PVL-positive ST1232-V (5C2&5), PVL-negative community-associated ST398-V (5C2&5) and livestock-associated ST398-V (5C2&5). Our findings demonstrate the importance of using whole genome sequencing and comparing the sequences to international sequences to distinguish between CC398 CA- and LA- MRSA and to determine the isolates' origin. Furthermore, our findings suggest CC398 CA-MRSA has become established in the Australian community and ST398-V (5C2&5) LA-MRSA is now widespread in Australian piggeries. Our study emphasizes the need of national one health antimicrobial resistance surveillance programs to assist in monitoring the ongoing epidemiology of MRSA and other clinically significant antimicrobial resistant organisms.

The increased length of hospital stay and mortality associated with community-associated infections in Australia

Background

An increasing proportion of antibiotic-resistant infections are community acquired. However, the burden of community-associated infections (CAIs) and the resulting impact due to resistance have not been well described.

Methods

We conducted a multisite, retrospective case–cohort study of all acute care hospital admissions across 134 hospitals in Australia. Patients admitted with a positive culture of 1 of 5 organisms of interest, namely Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecium, from January 1, 2012, through December 30, 2016, were included. Data linkage was used to link hospital admissions and pathology data. Patients with a bloodstream infection (BSI), urinary tract infection (UTI), or respiratory tract infection (RTI) were included in the analysis. We compared patients with a resistant and drug-sensitive infection and used regression analyses to derive the difference in length of hospital stay (LOS) and mortality estimates associated with resistance.

Results

No statistically significant impact on hospital LOS for patients with resistant CAIs compared with drug-sensitive CAIs was identified. CAI patients with drug-resistant Enterobacteriaceae (E. coli, K. pneumoniae) BSIs were more likely to die in the hospital than those with drug-sensitive Enterobacteriaceae BSIs (odds ratio [OR], 3.28; 95% CI, 1.40–6.92). CAI patients with drug-resistant P. aeruginosa UTIs were more likely to die in the hospital than those with the drug-sensitive counterpart (OR, 2.43; 95% CI, 1.12–4.85).

Conclusions

The burden of CAI in the hospital is significant, and antibiotic resistance is adding to associated mortality.

Common microbial isolates in an adult intensive care unit before and after its relocation and expansion

Objective: To describe the prevalence of common and clinically relevant microbial isolates before and after the migration of a 24-bed, open plan, adult intensive care unit (ICU) to a new extended design of 32 single rooms, supporting an expanded clinical oncology casemix while continuing all existing clinical services. Design: Retrospective, observational descriptive analysis covering the period 5 May 2014 to 4 May 2018 - the 2 years before and after the ICU relocation on 5 May 2016. Setting: A university-associated, tertiary teaching hospital and state trauma centre in Victoria, Australia. Patients: Adult ICU patients. Main outcome measures: Bacterial isolate frequency and incident rate ratios (IRRs) during the study period. Results: When compared with the old ICU, the incidence rates per 1000 occupied bed-days in the new ICU were lower for bacterial isolates overall (IRR, 0.88; 95% CI, 0.83-0.93), for coagulase-negative staphylococci (IRR, 0.64; 95% CI, 0.55-0.75) and for vancomycin-resistant enterococci (IRR, 0.50; 95% CI, 0.32-0.80). The incidence rates per 1000 occupied bed-days between ICU locations were unchanged for Staphylococcus aureus (IRR, 1.1; 95% CI, 0.91-1.3), extended-spectrum beta-lactamase-producing organisms (IRR, 1.4; 95% CI, 0.78-2.6) and carbapenemase-producing Enterobacterales (IRR, 0.85; 95% CI, 0.11-6.4). Conclusion: Within the limits of a before-after design and clinically directed sampling, relocation to a new ICU with single rooms and a growing oncological patient casemix was accompanied by no overall change in the apparent prevalence of the nosocomial pathogens S. aureus, extended-spectrum beta-lactamase-producing organisms or carbapenemase-producing Enterobacterales. These finding suggest that advanced physical infrastructure, including patient accommodation in single rooms, may play a role in overall safe delivery of critical care.

Antimicrobial Resistance Surveillance to Support Decision-Making in a High-Prevalence Region: An Evaluation

Despite a high use of antibiotics and a significant burden of infectious disease, ongoing monitoring and reporting of antimicrobial resistant pathogens in rural and regional Australia is insufficient. Many geographically isolated regions of Australia have limited infrastructure, resources and fall outside of surveillance reach, limiting health services’ ability to provide an early warning signal and appropriate response. To monitor trends in the development of antimicrobial resistance (AMR), identify high-risk populations and to evaluate effectiveness of control and prevention in rural and regional Australia, a subnational surveillance system termed HOTspots was developed. To promote the best use of public health resources through the development of effective and efficient surveillance systems, we evaluated HOTspots and its prototype surveillance platform for data quality, acceptability, representativeness, and timeliness. We used the Centers for Disease Prevention and Control (CDC) guidelines for evaluating public health surveillance systems and assessed the four attributes using a descriptive analysis of quantitative data and a thematic analysis of qualitative data. We report that the HOTspots surveillance system and its prototype platform effectively captures and represents AMR data across Northern Australia. The descriptive analysis of HOTspots data demonstrated some variation in data completeness but that data validity and representativeness were high. Thematic analysis of interview transcripts found that the system was acceptable, with almost all study participants identifying timeliness, online accessibility, and community representativeness as drivers for adoption of the system, and that the system provided timely data. The evaluation also identified areas for improvement and made recommendations to the HOTspots surveillance system and its associated prototype platform.

Efficacy and Safety of Intravenous Lincosamide Therapy in Methicillin-Resistant Staphylococcus aureus Bacteremia

Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia has a high case-fatality rate, but currently recommended antimicrobial therapies have many shortcomings. The efficacy and safety of lincosamide therapy for MRSA bacteremia is incompletely defined. A retrospective audit was done of the management of all adults with MRSA bacteremia at an Australian tertiary referral hospital between 1 January 2007 and 31 December 2020. A total of 176 patients were included. The case-fatality rate declined from 14/57 (25%) in the first half of the study to 12/119 (10%) in the second half (P = 0.01). Of the 172 patients receiving antibiotics, 62 (36%) received a lincosamide-predominant regimen (lincosamide monotherapy for >50% of the intravenous course). The patients receiving lincosamide-predominant intravenous therapy had lower in-hospital mortality (odds ratio [OR], 0.07; 95% confidence interval [CI], 0.01 to 0.53; P = 0.01) and a lower incidence of renal complications (OR [95% CI], 0.34 [0.15-0.75]; P = 0.008) than patients receiving an alternative regimen. In multivariate analysis that also considered age, disease severity, comorbidity, infectious diseases consultation, source control, and the year of admission, patients receiving a lincosamide-predominant regimen were still less likely to die in the hospital than those receiving an alternative regimen (OR [95% CI], 0.05 [0.00 to 0.65]; P = 0.02). Lincosamides appear to have utility, at least as stepdown therapy, in the treatment of MRSA bacteremia, particularly in young, clinically stable patients with few comorbidities in whom endocarditis has been excluded. Prospective studies will help define their optimal role.

Antimicrobial stewardship in rural and remote primary health care: a narrative review

BACKGROUND

Antimicrobial resistance is an emerging problem worldwide and poses a significant threat to human health. Antimicrobial stewardship programmes are being implemented in health systems globally, primarily in hospitals, to address the growing threat of antimicrobial resistance. Despite the significance of primary health care services in providing health care to communities, antimicrobial stewardship programmes are not well established in this sector, especially in rural and remote settings. This narrative review aims to identify in rural and remote primary health care settings the (1) correlation of antimicrobial resistance with antibiotic prescribing and volume of antibiotic use, (2) appropriateness of antimicrobial prescribing, (3) risk factors associated with inappropriate use/prescribing of antibiotics, and (4) effective antimicrobial stewardship strategies.

METHODS

The international literature was searched for English only articles between 2000 and 2020 using specified keywords. Seven electronic databases were searched: Scopus, Cochrane, Embase, CINAHL, PubMed, Ovid Medline and Ovid Emcare. Publication screening and analysis were conducted using Joanna Briggs Institute systematic review tools.

RESULTS

Fifty-one eligible articles were identified. Inappropriate and excessive antimicrobial prescribing and use directly led to increases in antimicrobial resistance. Increasing rurality of practice is associated with disproportionally higher rates of inappropriate prescribing compared to those in metropolitan areas. Physician knowledge, attitude and behaviour play important roles in mediating antimicrobial prescribing, with strong intrinsic and extrinsic influences including patient factors. Antimicrobial stewardship strategies in rural and remote primary health care settings focus on health care provider and patient education, clinician support systems, utility of antimicrobial resistance surveillance, and policy changes. Results of these interventions were generally positive with decreased antimicrobial resistance rates and improved appropriateness of antimicrobial prescribing.

CONCLUSIONS

Inappropriate prescribing and excessive use of antimicrobials are an important contributor to the increasing resistance towards antimicrobial agents particularly in rural and remote primary health care. Antimicrobial stewardship programmes in the form of education, clinical support, surveillance, and policies have been mostly successful in reducing prescribing rates and inappropriate prescriptions. The narrative review highlighted the need for longer interventions to assess changes in antimicrobial resistance rates. The review also identified a lack of differentiation between rural and remote contexts and Indigenous health was inadequately addressed. Future research should have a greater focus on effective interventional components and patient perspectives.

Longitudinal whole-genome based comparison of carriage and infection associated Staphylococcus aureus in northern Australian dialysis clinics

Background

The study objective was to reveal reservoirs potentially leading to Staphylococcus aureus infections in haemodialysis clinic clients in the tropical north of the Australian Northern Territory (NT). This client population are primarily Aboriginal Australians who have a greater burden of ill health than other Australians. Reservoir identification will enhance infection control in this client group, including informing potential S. aureus decolonisation strategies.

Methods and findings

The study participants were 83 clients of four haemodialysis clinics in the Darwin region of the NT, and 46 clinical staff and researchers who had contact with the clinic clients. The study design was longitudinal, encompassing swabbing of anatomical sites at two month intervals to yield carriage isolates, and also progressive collection of infection isolates. Swab sampling was performed for all participants, and infection isolates collected for dialysis clients only. Analysis was based on the comparison of 139 carriage isolates and 27 infection isolates using whole genome sequencing. Genome comparisons were based on of 20,651 genome-wide orthologous SNPs, presence/absence of the mecA and pvl genes, and inferred multilocus sequence type and clonal complex. Pairs of genomes meeting the definition of “not discriminated” were classed as defining potential transmission events. The primary outcome was instances of potential transmission between a carriage site other than a skin lesion and an infection site, in the same individual. Three such instances were identified. Two involved ST762 (CC1) PVL- MRSA, and one instance ST121 PVL+ MSSA. Three additional instances were identified where the carriage strains were derived from skin lesions. Also identified were six instances of potential transmission of a carriage strains between participants, including transmission of strains between dialysis clients and staff/researchers, and one potential transmission of a clinical strain between participants. There were frequent occurrences of longitudinal persistence of carriage strains in individual participants, and two examples of the same strain causing infection in the same participants at different times.

Strains associated with infections and skin lesions were enriched for PVL and mecA in comparison to strains associated with long term carriage.

Conclusions

This study indicated that strains differ with respect to propensity to stably colonise sites such as the nose, and cause skin infections. PVL+ strains were associated with infection and skin lesions and were almost absent from the carriage sites. PVL- MRSA (mainly CC1) strains were associated with infection and also with potential transmission events involving carriage sites, while PVL- MSSA were frequently observed to stably colonise individuals without causing infection, and to be rarely transmitted. Current clinical guidelines for dialysis patients suggest MRSA decolonisation. Implementation in this client group may impact infections by PVL- MRSA, but may have little effect on infection by PVL+ strains. In this study, the PVL+ strains were predominant causes of infection but rarely colonised typical carriage sites such as the nose, and in the case of ST121, were MSSA. The important reservoirs for infection by PVL+ strains appeared to be prior infections.