Antimicrobial resistance determinants are associated with Staphylococcus aureus bacteraemia and adaptation to the healthcare environment: a bacterial genome-wide association study

Staphylococcus aureus is a major bacterial pathogen in humans, and a dominant cause of severe bloodstream infections. Globally, antimicrobial resistance (AMR) in S. aureus remains challenging. While human risk factors for infection have been defined, contradictory evidence exists for the role of bacterial genomic variation in S. aureus disease. To investigate the contribution of bacterial lineage and genomic variation to the development of bloodstream infection, we undertook a genome-wide association study comparing bacteria from 1017 individuals with bacteraemia to 984 adults with asymptomatic S. aureus nasal carriage. Within 984 carriage isolates, we also compared healthcare-associated (HA) carriage with community-associated (CA) carriage. All major global lineages were represented in both bacteraemia and carriage, with no evidence for different infection rates. However, kmers tagging trimethoprim resistance-conferring mutation F99Y in dfrB were significantly associated with bacteraemia-vs-carriage (P=10-8.9-10-9.3). Pooling variation within genes, bacteraemia-vs-carriage was associated with the presence of mecA (HMP=10-5.3) as well as the presence of SCCmec (HMP=10-4.4). Among S. aureus carriers, no lineages were associated with HA-vs-CA carriage. However, we found a novel signal of HA-vs-CA carriage in the foldase protein prsA, where kmers representing conserved sequence allele were associated with CA carriage (P=10-7.1-10-19.4), while in gyrA, a ciprofloxacin resistance-conferring mutation, L84S, was associated with HA carriage (P=10-7.2). In an extensive study of S. aureus bacteraemia and nasal carriage in the UK, we found strong evidence that all S. aureus lineages are equally capable of causing bloodstream infection, and of being carried in the healthcare environment. Genomic variation in the foldase protein prsA is a novel genomic marker of healthcare origin in S. aureus but was not associated with bacteraemia. AMR determinants were associated with both bacteraemia and healthcare-associated carriage, suggesting that AMR increases the propensity not only to survive in healthcare environments, but also to cause invasive disease

Adjunctive rifampicin for Staphylococcus aureus bacteraemia (ARREST): a multicentre, randomised, double-blind, placebo-controlled trial.

BACKGROUND: Staphylococcus aureus bacteraemia is a common cause of severe community-acquired and hospital-acquired infection worldwide. We tested the hypothesis that adjunctive rifampicin would reduce bacteriologically confirmed treatment failure or disease recurrence, or death, by enhancing early S aureus killing, sterilising infected foci and blood faster, and reducing risks of dissemination and metastatic infection. METHODS: In this multicentre, randomised, double-blind, placebo-controlled trial, adults (≥18 years) with S aureus bacteraemia who had received ≤96 h of active antibiotic therapy were recruited from 29 UK hospitals. Patients were randomly assigned (1:1) via a computer-generated sequential randomisation list to receive 2 weeks of adjunctive rifampicin (600 mg or 900 mg per day according to weight, oral or intravenous) versus identical placebo, together with standard antibiotic therapy. Randomisation was stratified by centre. Patients, investigators, and those caring for the patients were masked to group allocation. The primary outcome was time to bacteriologically confirmed treatment failure or disease recurrence, or death (all-cause), from randomisation to 12 weeks, adjudicated by an independent review committee masked to the treatment. Analysis was intention to treat. This trial was registered, number ISRCTN37666216, and is closed to new participants. FINDINGS: Between Dec 10, 2012, and Oct 25, 2016, 758 eligible participants were randomly assigned: 370 to rifampicin and 388 to placebo. 485 (64%) participants had community-acquired S aureus infections, and 132 (17%) had nosocomial S aureus infections. 47 (6%) had meticillin-resistant infections. 301 (40%) participants had an initial deep infection focus. Standard antibiotics were given for 29 (IQR 18-45) days; 619 (82%) participants received flucloxacillin. By week 12, 62 (17%) of participants who received rifampicin versus 71 (18%) who received placebo experienced treatment failure or disease recurrence, or died (absolute risk difference -1·4%, 95% CI -7·0 to 4·3; hazard ratio 0·96, 0·68-1·35, p=0·81). From randomisation to 12 weeks, no evidence of differences in serious (p=0·17) or grade 3-4 (p=0·36) adverse events were observed; however, 63 (17%) participants in the rifampicin group versus 39 (10%) in the placebo group had antibiotic or trial drug-modifying adverse events (p=0·004), and 24 (6%) versus six (2%) had drug interactions (p=0·0005). INTERPRETATION: Adjunctive rifampicin provided no overall benefit over standard antibiotic therapy in adults with S aureus bacteraemia. FUNDING: UK National Institute for Health Research Health Technology Assessment

Some Drawings by Some Albertans

Presenting works by 51 Alberta artists, Mabie examines various definitions of drawing. Statements by 29 artists

Antibiotic Review Kit for Hospitals (ARK-Hospital): a stepped wedge cluster randomised controlled trial

Background: Strategies to reduce antibiotic overuse in hospitals depend on prescribers taking decisions to stop unnecessary antibiotics. There is limited evidence on how to support this. We evaluated a multifaceted behaviour change intervention (ARK) designed to reduce antibiotic use among adult acute/medical inpatients by increasing appropriate decisions to stop antibiotics at clinical review. Methods: We performed a stepped-wedge, cluster (hospital)-randomised controlled trial using computer-generated sequence randomisation of 39 hospitals in 7 calendar-time blocks in the United Kingdom (25/September/2017-01/July/2019). Randomised implementation date was concealed until 12 weeks before implementation, when local preparations were designed to start. Co-primary outcomes were monthly antibiotic defined-daily-doses (DDD) per adult acute/medical admission (hospital-level, superiority) and all-cause 30-day mortality (patient level, non-inferiority, margin 5%). Sites were eligible if they admitted non-elective medical patients, could identify an intervention “champion”, and provide study data. Sites werefollowed for at least 14 months. Intervention effects were assessed using interrupted timeseries analyses within each site, estimating overall effects through random-effects meta analysis, with heterogeneity across prespecified potential modifiers assessed using meta regression.Trial registration: ISRCTN12674243.Findings: Adjusted estimates showed reductions in total antibiotic DDDs per acute/medicaladmission (-4.8% per year, 95% CI: -9.1%,-0.2%) following the intervention. Among7,160,421 acute/medical admissions, there were trends towards -2.7% (95% CI: -5.7%,+0.3%) immediate and +3.0% (95% CI: -0.1%,+6.2%) sustained changes in adjusted30-day mortality. Site-specific mortality trends were unrelated to the site-specific magnitudeof antibiotic reduction (Spearman’s ρ=0.011, p=0.949). Whilst 90-day mortality oddsappeared to increase (+3.9%, 95% CI: +0.5%,+7.4%), this was attenuated excludingadmissions after COVID-19 onset (+3.2%, 95% CI:-1.5%,+8.2%). There was no evidence ofintervention effects on length-of-stay (p>0.4).Interpretation: The weak, inconsistent intervention effects on mortality are likely explained by the post-implementation onset of the COVID-19 pandemic. The ARK intervention resulted in sustained, safe reductions in antibiotic use among adult acute/medical inpatients. Funding: NIHR Programme Grants for Applied Research, RP-PG-0514-20015