Colonization pressure adjusted by degree of environmental contamination: a better indicator for predicting methicillin-resistant Staphylococcus aureus acquisition

Sustained fall in inpatient MRSA prevalence after a video-reflexive ethnography project; an observational study

BACKGROUND

Maintaining optimal infection prevention and control (IPC) in a busy, clinical environment is challenging. Video-reflexive ethnography (VRE) is a collaborative, interventionist approach to practice improvement. We hypothesised that giving clinicians opportunities to view and reflect on video footage of everyday ward activities would raise awareness of, and suggest strategies to reduce, pathogen transmission risks. We undertook a VRE project, between March and September 2013, in two tertiary hospital surgical wards, with persistently high methicillin resistant Staphylococcus aureus (MRSA) endemicity, despite previous IPC interventions.

METHODS

This study was a retrospective/prospective observational study, using interrupted time-series analyses, to assess the effects of the VRE project on hand hygiene compliance, inpatient MRSA infections (newly infected patients, per 1000 occupied bed days) and inpatient MRSA colonisation prevalence, measured by serial point prevalence surveys. Follow-up continued until June 2016.

RESULTS

The VRE project was associated with changes in IPC behaviour and outcomes. Hand hygiene compliance increased (from 62% to 75%; p < 0.0001) and MRSA colonisation prevalence decreased significantly, in both wards (baseline 42%; average post-VRE 12%; p=<0.0001), MRSA infection rate decreased in one ward. Interpretation of results was complicated by a potential confounding effect of unplanned environmental hydrogen peroxide decontamination (HPD). Improved hand hygiene compliance was a predicted outcome of VRE, but also a potential contributor to reduced MRSA transmission.

CONCLUSION

Separate contributions of VRE (the intervention), HPD and hand hygiene compliance were uncertain, but their combined effect was significantly reduced MRSA endemicity, which previously had been resistant to attempted IPC interventions.

The impact of antibiotic use on transmission of resistant bacteria in hospitals: Insights from an agent-based model

Extensive antibiotic use over the years has led to the emergence and spread of antibiotic resistant bacteria (ARB). Antibiotic resistance poses a major threat to public health since for many infections antibiotic treatment is no longer effective. Hospitals are focal points for ARB spread. Antibiotic use in hospitals exerts selective pressure, accelerating the spread of ARB. We used an agent-based model to explore the impact of antibiotics on the transmission dynamics and to examine the potential of stewardship interventions in limiting ARB spread in a hospital. Agents in the model consist of patients and health care workers (HCW). The transmission of ARB occurs through contacts between patients and HCW and between adjacent patients. In the model, antibiotic use affects the risk of transmission by increasing the vulnerability of susceptible patients and the contagiousness of colonized patients who are treated with antibiotics. The model shows that increasing the proportion of patients receiving antibiotics increases the rate of acquisition non-linearly. The effect of antibiotics on the spread of resistance depends on characteristics of the antibiotic agent and the density of antibiotic use. Antibiotic's impact on the spread increases when the bacterial strain is more transmissible, and decreases as resistance prevalence rises. The individual risk for acquiring ARB increases in parallel with antibiotic density both for patients treated and not treated with antibiotics. Antibiotic treatment in the hospital setting plays an important role in determining the spread of resistance. Interventions to limit antibiotic use have the potential to reduce the spread of resistance, mainly by choosing an agent with a favorable profile in terms of its impact on patient's vulnerability and contagiousness. Methods to measure these impacts of antibiotics should be developed, standardized, and incorporated into drug development programs and approval packages.

Occurrence of nosocomial methicillin-resistant Staphylococcus aureus as a marker for transmission in a surgical intensive care unit in China

In 2008, an intensive care unit (ICU) in a large Chinese hospital was moved from a 6-bed old ward to a 20-bed new ward. After the move, the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in patients and environmental sites decreased significantly, but the number of ICU-acquired cases per imported MRSA case increased from 1.4 to 4.1. This study suggests that the nurse cohorting level and hand hygiene compliance are strong predicators of MRSA transmission in ICUs.

Comparing the transmission potential of Methicillin-resistant Staphylococcus aureus and multidrug-resistant Acinetobacter baumannii among inpatients using target environmental monitoring

BACKGROUND

With the increasing isolation rate of multidrug-resistant Acinetobacter baumannii (MDR-AB) in China hospitals, more researches focused on its antimicrobial resistance, but few studies reported its nosocomial transmission. In this study, we aim to investigate the transmission features of MDR-AB among inpatients using target environmental monitoring.

METHODS

Methicillin-resistant Staphylococcus aureus (MRSA) and MDR-AB active screening and target environmental screening were performed from March 2010 to October 2011 in respiratory intensive care unit (RICU). We compared bed linen contamination rate and acquisition rate of MDR-AB with those of MRSA and analyzed the correlation between weekly colonization pressure adjusted by degree of bed linen contamination (WCPe) and weekly acquisition rate (WAR) of MDR-AB.

RESULTS

We found that both the bed linen contamination rate and the acquisition rate of MDR-AB were higher than those of MRSA (χ(2) = 98.081, P < .01; χ(2) = 49.844, P < .01, respectively). The correlation analysis showed positive correlation between MDR-AB WCPe and WAR (rs = 0.560, P < .01). The WCPe and WAR of MDR-AB were higher than those of MRSA (Z = -5.439, P < .01; Z = -3.258, P < .01, respectively).

CONCLUSION

Compared with MRSA, MDR-AB carriers showed stronger ability to contaminate their immediate environment, and MDR-AB was easier to transmit among inpatients. Therefore, it was likely more important to perform active environmental monitoring as a method of transmission evaluation and a measure of routine infection control to prevent and control MDR-AB nosocomial transmission more effectively.