Daily Sepsis Research Analysis
Policy-level decolonisation strategy shifts in ICUs, rapid antibiotic susceptibility testing directly from positive blood cultures, and nurse staffing effects on hospital-onset MRSA bloodstream infections emerged as key themes. Together, these studies inform antimicrobial stewardship, diagnostic acceleration for bloodstream infections, and hospital infection prevention.
Summary
Policy-level decolonisation strategy shifts in ICUs, rapid antibiotic susceptibility testing directly from positive blood cultures, and nurse staffing effects on hospital-onset MRSA bloodstream infections emerged as key themes. Together, these studies inform antimicrobial stewardship, diagnostic acceleration for bloodstream infections, and hospital infection prevention.
Research Themes
- ICU decolonisation strategies and resistance selection
- Rapid antimicrobial susceptibility testing from positive blood cultures
- Nurse staffing and prevention of hospital-onset MRSA bloodstream infections
Selected Articles
1. Universal versus targeted chlorhexidine and mupirocin decolonisation and clinical and molecular epidemiology of Staphylococcus epidermidis bloodstream infections in patients in intensive care in Scotland, UK: a controlled time-series and longitudinal genotypic study.
In two Scottish ICUs, de-escalating from universal to targeted decolonisation reduced MRSE bloodstream infections and the probability that SE-BSI were MRSE, without increasing overall BSI. Chlorhexidine exposure correlated with MRSE-BSI incidence, and genotyping showed fewer multidrug-resistant sequence types after de-escalation.
Impact: This quasi-experimental, genomics-informed study challenges the assumption that universal decolonisation is uniformly beneficial and links chlorhexidine pressure to MRSE selection, informing ICU infection prevention policies.
Clinical Implications: ICUs with low MRSA prevalence should consider targeted rather than universal decolonisation and monitor for MRSE selection under chlorhexidine use, balancing device-associated infection risks and resistance ecology.
Key Findings
- MRSE-BSI incidence declined from 10.4 to 4.3 per 1000 occupied bed days after de-escalation at the intervention ICU.
- The percentage probability that SE-BSI were MRSE decreased from 89.2% to 56.7% post-de-escalation.
- MRSE-BSI incidence density was positively associated with chlorhexidine use, but not mupirocin use.
- Genotyping and WGS indicated fewer multidrug-resistant sequence types and resistance/biofilm genes after de-escalation.
Methodological Strengths
- Before-after-control-impact time-series design across two ICUs
- Integrated antimicrobial susceptibility, MLST, and whole-genome sequencing over a 12+ year period
Limitations
- Retrospective, non-randomised design susceptible to secular trends and unmeasured confounding
- Findings from two ICUs in low-MRSA settings may limit generalisability
Future Directions: Prospective multicentre evaluations of decolonisation strategies stratified by local MRSA prevalence, coupled with resistome surveillance and device-associated infection outcomes.
BACKGROUND: There are concerns that biocide skin and mucous membrane decolonisation, which is widely used to prevent health-care-associated infections in intensive care units (ICUs), might select for multidrug-resistant pathogens. We aimed to evaluate the effects of de-escalating from universal to targeted skin and nasal decolonisation on Staphylococcus epidermidis bloodstream infections (SE-BSI). METHODS: We did a retrospective, before-after-control-impact time-series analysis and longitudinal genotypic study in two ICUs with divergent decolonisation practice in tertiary care hospitals of adjacent health boards in Scotland, UK. Participants were aged at least 16 years and admitted between July 1, 2009, and Feb 28, 2022. There were no exclusion criteria for the study. In ICU one (intervention site) universal decolonisation in all admissions was de-escalated to targeted decolonisation of meticillin-resistant Staphylococcus aureus (MRSA) carriers on Feb 1, 2019, while in ICU two (control site) targeted decolonisation was applied throughout. We collected bloodstream infection data from all causes, including clinically significant SE-BSI. Antimicrobial susceptibility testing was used to define meticillin-resistant S epidermidis (MRSE) and chlorhexidine susceptibility. We used multilocus sequence typing to identify sequence types from archived SE-BSI isolates. Whole-genome sequencing was applied to a sample from ICU one. The primary outcomes were incidence densities of all bloodstream infections, SE-BI, and meticillin-resistant S epidermidis bloodstream infections (MRSE-BSI), and the percentage probability that SE-BSI were MRSE-BSI. The effects of de-escalation on primary outcomes were estimated by differences between the intervention and control sites, before and after de-escalation, using a before-after-control-impact time-series design. Secondary outcomes included the proportion of multidrug resistant sequence types, carriage of mobile genetic elements and genes for multidrug resistance and biofilm production. FINDINGS: Between July 1, 2009, and Feb 28, 2022, S epidermidis was identified in 334 (45%) of 735 bloodstream infections in ICU one, of which 197 occurred before the de-escalation intervention in Feb 1, 2019, and S epidermidis was identified in 167 (60%) of 278 bloodstream infections in ICU two. There was no increase in all bloodstream infection incidence coinciding with de-escalation in ICU one, whereas MRSE-BSI incidence declined significantly from 10·4 cases per 1000 occupied bed days (OBDs; 95% credible interval [CrI] 7·2-15·4) to 4·3 cases per 1000 OBDs (2·5-6·7), as did the percentage probability of MRSE (from 89·2%, 95% CrI 77·8-96·5 to 56·7%, 34·3-77·5%). No significant changes in the primary outcomes were seen in ICU two. MRSE-BSI incidence density was positively associated with chlorhexidine use, but not mupirocin use. De-escalation was associated with a reduced proportion of SE-BSI due to multidrug-resistant sequence types and reduced carriage of mobile genetic elements and genes for multidrug resistance and biofilm production, as observed by multi-locus sequence typing and whole genome sequencing. INTERPRETATION: In ICU settings with low MRSA incidence, the benefits of universal decolonisation should be balanced against the risks of selecting MRSE sequence types adapted for invasive and device-associated infection. FUNDING: National Health Service Grampian Charity.
2. Registered nurse workload and hospital-onset methicillin-resistant Staphylococcus aureus bloodstream infections.
Using national administrative datasets, each additional RN hour per patient day correlated with a 3% reduction in hospital-onset MRSA bloodstream infection rates. These findings underscore the infection prevention value of adequate nurse staffing.
Impact: Quantifies a direct association between nurse staffing and a key bloodstream infection outcome, informing staffing policies and infection prevention planning.
Clinical Implications: Hospitals should consider nurse staffing levels as a modifiable lever to reduce hospital-onset MRSA BSI, integrating staffing metrics into infection control programs.
Key Findings
- Each additional RN hour per patient day was associated with a 3% decrease in hospital-onset MRSA bloodstream infection rate.
- Analysis leveraged data from the American Hospital Association Survey and Centers for Medicare & Medicaid Services.
Methodological Strengths
- Use of large national datasets across hospitals
- Clear, interpretable effect size per RN hour per patient day
Limitations
- Observational design cannot establish causality and may be confounded by hospital case mix and resources
- Limited methodological details in the abstract; lack of patient-level covariates described
Future Directions: Prospective evaluations of staffing interventions and cost-effectiveness analyses to guide policy; explore effects on other HAIs.
The prevention of methicillin-resistant Staphylococcus aureus (MRSA) is a national priority. Data from the American Hospital Association Survey and the Centers for Medicare & Medicaid Services show that each additional registered nurse hour per patient day was associated with a 3% decrease in the rate of hospital-onset MRSA bloodstream infection.
3. Evaluation of EUCAST rapid antibiotic susceptibility testing for positive blood cultures in the Autobio BC60 blood culture system.
In 234 spiked positive blood culture samples, EUCAST RAST on the Autobio BC system achieved high categorical agreement (≈99–100%) with standard disk diffusion at 4–20 hours, with 0% major errors and 1.3% very major errors across time points. This supports earlier AST reporting directly from positive bottles.
Impact: Validates rapid AST directly from positive blood cultures on a widely used system with excellent agreement metrics, enabling faster targeted therapy for bloodstream infections.
Clinical Implications: Laboratories using Autobio BC can implement EUCAST RAST with QC to provide reliable AST results within hours of positivity, expediting de-escalation/escalation in sepsis management.
Key Findings
- High categorical agreement for RAST vs sDD at 4, 8, and 20 hours across six species (≈98.7–100%).
- Very major errors were 1.3% and major errors 0% at all time points; minor errors ≤1.4%.
- Feasibility of performing EUCAST RAST directly on positive Autobio BC bottles with reliable outcomes.
Methodological Strengths
- Standardised head-to-head comparison with sDD across multiple time points
- Coverage of key Gram-negative and Gram-positive pathogens with species-specific metrics
Limitations
- Spiked samples rather than consecutive clinical isolates; lacks patient outcome correlation
- Single blood culture platform; external validity to other systems not assessed
Future Directions: Prospective clinical validation linking RAST-guided therapy to time-to-effective therapy and patient outcomes; assess performance across different blood culture systems.
Early diagnosis and effective treatment of bloodstream infections significantly improve prognosis. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) has developed rapid antimicrobial susceptibility testing(RAST) based on the disk diffusion method. In the present study, we compared the data from the RAST study from positive blood cultures in the Autobio BC (Autobio-diagnostics, Zhengzhou, Chinese) blood culture system with those obtained using the standard disk diffusion method. A total of 234 spiked blood culture samples (Klebsiella penumoniae [n= 50], Escherichia coli [n= 50], Acinetobacter baumannii [n= 20], Pseudomonas aeruginosa [n= 13], Staphylococcus aureus [n= 51], and Enterococcus spp. [n= 50]) were collected. The RAST test was performed on positive bottles, and the results were measured at 4, 8, and 20 h. Standard disk diffusion (sDD) was performed, and zone diameters were measured from subculture samples obtained from blood culture bottles. The RAST zone diameters were compared with the sDD zone diameters. The categorical agreement based on the readable zone diameters for the 4th, 8th, and 20th h was K.pneumoniae (99.7 %,99.7 %,99.7 %), E.coli (99.4 %,99.6 %,99.7 %), A.baumannii (98.7 %,98.7 %,98.7 %), P.aeruginosa (100 %,99.3 %,100 %), S. aureus (100 %,100 %,100 %), and Enterococcus spp. (100 %,100 %,100 %). The minor error(mE), major error(ME), and very major error(VME) results obtained in the whole study were determined as 0.9, 0, and 1.3 for 4 h; 1.4, 0, and 1.3 for 8 h; 0.6, 0, and 1.3 for 20 h. The EUCAST RAST study can be performed from positive bottles in the Autobio BC blood culture system, resulting in reliable outcomes. To report earlier antibiotic susceptibility test results, laboratories using Autobio BC can combine RAST with quality control studies.