Genomic investigation of multispecies and multivariant blaNDM outbreak reveals key role of horizontal plasmid transmission.

OBJECTIVES: New Delhi metallo-ß-lactamases (NDMs) are major contributors to the spread of carbapenem resistance globally. In Australia, NDMs were previously associated with international travel, but from 2019 we noted increasing incidence of NDM-positive clinical isolates. We investigated the clinical and genomic epidemiology of NDM carriage at a tertiary-care Australian hospital from 2016 to 2021. METHODS: We identified 49 patients with 84 NDM-carrying isolates in an institutional database, and we collected clinical data from electronic medical record. Short- and long-read whole genome sequencing was performed on all isolates. Completed genome assemblies were used to assess the genetic setting of blaNDM genes and to compare NDM plasmids. RESULTS: Of 49 patients, 38 (78%) were identified in 2019-2021 and only 11 (29%) of 38 reported prior travel, compared with 9 (82%) of 11 in 2016-2018 (P = .037). In patients with NDM infection, the crude 7-day mortality rate was 0% and the 30-day mortality rate was 14% (2 of 14 patients). NDMs were noted in 41 bacterial strains (ie, species and sequence type combinations). Across 13 plasmid groups, 4 NDM variants were detected: blaNDM-1, blaNDM-4, blaNDM-5, and blaNDM-7. We noted a change from a diverse NDM plasmid repertoire in 2016-2018 to the emergence of conserved blaNDM-1 IncN and blaNDM-7 IncX3 epidemic plasmids, with interstrain spread in 2019-2021. These plasmids were noted in 19 (50%) of 38 patients and 35 (51%) of 68 genomes in 2019-2021. CONCLUSIONS: Increased NDM case numbers were due to local circulation of 2 epidemic plasmids with extensive interstrain transfer. Our findings underscore the challenges of outbreak detection when horizontal transmission of plasmids is the primary mode of spread.

Understanding patient and healthcare worker experiences and perspectives of multidrug-resistant organisms.

Objectives: Transmission of MDR organisms (MROs) such as carbapenemase-producing Enterobacteriaceae (CPE) and VRE in healthcare facilities is a major issue globally. Knowledge gaps exist, including the impact of these microorganisms on patients, and healthcare worker understanding of infection control approaches for MROs. This study aimed to explore patient and healthcare worker experiences and perspectives of MROs. Methods: A sequential exploratory mixed-methods study was performed at a large metropolitan acute and subacute hospital. This involved semi-structured face-to-face interviews with patients with confirmed MROs to explore their understanding of these microorganisms and perceptions of their time in hospital. Healthcare workers participated in an online survey about their understanding of MROs and the care of patients with these microorganisms. Qualitative data were analysed using the COM-B framework, and were triangulated with the descriptive quantitative analysis. Results: The overarching theme from the triangulated data was uncertainty amongst both patients and staff about MROs. Insufficient explanations from staff left patients lacking a proper understanding of their diagnosis, and patients felt that staff did not always follow isolation protocols. Staff felt they did not receive enough education on MROs. However, patients felt that the overall care they received was very good, and most valued the privacy gained from being in isolation. Conclusions: This study demonstrates that there is a need to focus on new strategies of communication with patients and staff education to improve understanding of MROs and increase adherence to protocols.

State-wide genomic epidemiology investigations of COVID-19 in healthcare workers in 2020 Victoria, Australia: Qualitative thematic analysis to provide insights for future pandemic preparedness.

Background: COVID-19 has affected many healthcare workers (HCWs) globally. We performed state-wide SARS-CoV-2 genomic epidemiological investigations to identify HCW transmission dynamics and provide recommendations to optimise healthcare system preparedness for future outbreaks. Methods: Genome sequencing was attempted on all COVID-19 cases in Victoria, Australia. We combined genomic and epidemiologic data to investigate the source of HCW infections across multiple healthcare facilities (HCFs) in the state. Phylogenetic analysis and fine-scale hierarchical clustering were performed for the entire dataset including community and healthcare cases. Facilities provided standardised epidemiological data and putative transmission links. Findings: Between March-October 2020, approximately 1,240 HCW COVID-19 infection cases were identified; 765 are included here, requested for hospital investigations. Genomic sequencing was successful for 612 (80%) cases. Thirty-six investigations were undertaken across 12 HCFs. Genomic analysis revealed that multiple introductions of COVID-19 into facilities (31/36) were more common than single introductions (5/36). Major contributors to HCW acquisitions included mobility of staff and patients between wards and facilities, and characteristics and behaviours of patients that generated numerous secondary infections. Key limitations at the HCF level were identified. Interpretation: Genomic epidemiological analyses enhanced understanding of HCW infections, revealing unsuspected clusters and transmission networks. Combined analysis of all HCWs and patients in a HCF should be conducted, supported by high rates of sequencing coverage for all cases in the population. Established systems for integrated genomic epidemiological investigations in healthcare settings will improve HCW safety in future pandemics. Funding: The Victorian Government, the National Health and Medical Research Council Australia, and the Medical Research Future Fund.

An effective strategy for influenza vaccination of healthcare workers in Australia: experience at a large health service without a mandatory policy.

BACKGROUND: Annual influenza vaccination of healthcare workers (HCWs) is recommended in Australia, but uptake in healthcare facilities has historically been low (approximately 50%). The objective of this study was to develop and implement a dedicated campaign to improve uptake of staff influenza annual vaccination at a large Australian health service. METHODS: A quality improvement program was developed at Alfred Health, a tertiary metropolitan health service spanning 3 campuses. Pre-campaign evaluation was performed by questionnaire in 2013 to plan a multimodal vaccination strategy. Reasons for and against vaccination were captured. A campaign targeting clinical and non-clinical healthcare workers was then implemented between March 31 and July 31 2014. Proportional uptake of influenza vaccination was determined by campus and staff category. RESULTS: Pre-campaign questionnaire responses were received from 1328/6879 HCWs (response rate 20.4%), of which 76% were vaccinated. Common beliefs held by unvaccinated staff included vaccine ineffectiveness (37.1%), that vaccination makes staff unwell (21.0%), or that vaccination is not required because staff are at low risk for acquiring influenza (20.2%). In 2014, 6009/7480 (80.3%) staff were vaccinated, with significant improvement in uptake across all campuses and amongst nursing, medical and allied health staff categories from 2013 to 2014 (p < 0.0001). CONCLUSIONS: A non-mandatory multimodal strategy utilising social marketing and a customised staff database was successful in increasing influenza vaccination uptake by all staff categories. The sustainability of dedicated campaigns must be evaluated.

Beyond the intensive care unit bundle: Implementation of a successful hospital-wide initiative to reduce central line-associated bloodstream infections.

A multimodal hospital-wide central line-associated bloodstream infection (CLABSI) risk reduction strategy was implemented over a 20-month period at an Australian center. Reduced CLABSI rates were observed in both intensive care units (ICUs) (incidence rate ratio [IRR], 0.39; P < .001) and non-ICU wards (IRR, 0.54; P < .001). The median time to CLABSI onset was 7.5 days for ICU events and 13 days for non-ICU events. The timing of infection demonstrates the need for more careful attention to postinsertion care and access of central venous catheters.

Impact of chlorhexidine-impregnated washcloths on reducing incidence of vancomycin-resistant enterococci colonization in hematology-oncology patients.

BACKGROUND: Daily skin cleansing with washcloths impregnated with chlorhexidine gluconate (CHG) of patients in intensive care unit is associated with reduction in incidence of vancomycin-resistant Enterococci (VRE) acquisition. This study describes the impact on incidence of VRE colonization after the implementation of daily skin cleansing with 2% CHG-impregnated washcloths in hematology-oncology patients. METHODS: In this before-and-after study, we compared the incidence rate of VRE colonization during the baseline period (where routine soap-and-water bathing was used) with the intervention period where patients were cleansed with 2% CHG-impregnated washcloths. RESULTS: Acquisition of VRE decreased from 7.8% in the baseline to 3.8% in the intervention period (relative risk, 0.48, 95% confidence interval [CI], 0.21-1.09; P = .07). The crude relative rate of acquisition during the intervention period compared with the baseline period was 0.53 (95% CI, 0.23-1.23; P = .13). Patients who had been a roommate of a patient subsequently found to have VRE were at a significantly increased risk for acquiring VRE (hazard ratio, 18.8, 95% CI, 5.37-66.15; P < .001). However, patients admitted to the same bed number of previously known VRE-colonized patient were not at increased risk of VRE acquisition (hazard ratio, 0.37, 95% CI, 0.11-1.22; P = .10). CONCLUSION: We did not observe a statistically significant reduction in the rate of VRE colonization in association with the use of 2% CHG-impregnated washcloths among hematology-oncology patients.

Prevalence and risk factors for VRE colonisation in a tertiary hospital in Melbourne, Australia: a cross sectional study.

BACKGROUND: Vancomycin-resistant Enterococcus (VRE) has been established as a significant health-care associated problem since its first isolation in Australia in 1994. In this study, we measured the point prevalence and identified risk factors associated with vanB VRE colonisation in a tertiary care hospital in Melbourne, Australia where VRE has been endemic for 15 years. METHODS: A hospital-wide point prevalence survey was conducted on October 13, 2008 with colonisation detected using rectal swab culture. Patient's demographic and medical information was collected through a review of medical records. Factors associated with VRE colonisation in univariate analysis were included in multivariate logistic regression model to adjust for confounding. RESULTS: The prevalence of VRE colonisation on the day of screening was 17.5% (95% CI, 13.7 to 21.9). VRE was detected from patients in each ward with the prevalence ranging from 3% to 29%. Univariate analysis showed the use of any antibiotic, meropenem, ciprofloxacin, diarrhoea and longer length of hospital stay were associated with increased risk of VRE colonisation (p<0.05). However, age, sex, proximity to VRE positive cases, use of other antibiotics including cephalosporins, vancomycin were not associated with increased risk (P>0.05). Multivariate analysis showed the exposure to meropenem (p=0.004), age (≥65 years) (p=0.036) and length of stay ≥7 days (p<0.001) as independent predictors of VRE colonisation. CONCLUSION: Our study suggests that exposure to antibiotics may have been more important than recent cross transmission for a high prevalence of vanB VRE colonisation at our hospital.

Reduction in hospitalwide incidence of infection or colonization with methicillin-resistant Staphylococcus aureus with use of antimicrobial hand-hygiene gel and statistical process control charts.

OBJECTIVE: To evaluate the impact of serial interventions on the incidence of methicillin-resistant Staphylococcus aureus (MRSA). DESIGN: Longitudinal observational study before and after interventions. SETTING: The Alfred Hospital is a 350-bed tertiary referral hospital with a 35-bed intensive care unit (ICU). INTERVENTIONS: A series of interventions including the introduction of an antimicrobial hand-hygiene gel to the intensive care unit and a hospitalwide MRSA surveillance feedback program that used statistical process control charts but not active surveillance cultures. METHODS: Serial interventions were introduced between January 2003 and May 2006. The incidence and rates of new patients colonized or infected with MRSA and episodes of MRSA bacteremia in the intensive care unit and hospitalwide were compared between the preintervention and intervention periods. Segmented regression analysis was used to calculate the percentage reduction in new patients with MRSA and in episodes of MRSA bacteremia hospitalwide in the intervention period. RESULTS: The rate of new patients with MRSA in the ICU was 6.7 cases per 100 patient admissions in the intervention period, compared with 9.3 cases per 100 patient admissions in the preintervention period (P=.047). The hospitalwide rate of new patients with MRSA was 1.7 cases per 100 patient admissions in the intervention period, compared with 3.0 cases per 100 patient admissions in the preintervention period (P<.001). By use of segmented regression analysis, the maximum and conservative estimates for percentage reduction in the rate of new patients with MRSA were 79.5% and 42.0%, respectively, and the maximum and conservative estimates for percentage reduction in the rate of episodes of MRSA bacteremia were 87.4% and 39.0%, respectively. CONCLUSION: A sustained reduction in the number of new patients with MRSA colonization or infection has been demonstrated using minimal resources and a limited number of interventions.