Caroline Marshall

Objective: To determine whether operating room (OR) shoe covers prevent surgical site infections (SSIs) and to assess their environmental and clinical impact. Design: Scoping review. Setting: Hospital operating room environments in international healthcare systems. Methods: We searched Emcare, Embase, MEDLINE, and SCOPUS for studies examining shoe covers and outcomes related to bacterial contamination or SSIs. Data were synthesized descriptively. Results: Six studies met inclusion criteria. Evidence was mixed regarding bacterial contamination: some showed fewer colony forming units with shoe covers, while others found no effect or even higher contamination. Only one study assessed clinical outcomes, reporting fewer SSIs following reduced use of disposable PPE (including shoe covers). No study demonstrated a direct SSI reduction from shoe covers alone. Conclusions: Evidence does not support OR shoe covers in preventing SSIs. Their use adds environmental burden through single-use plastics. More rigorous studies are needed to confirm these findings and guide sustainable infection prevention practices.

Background Outbreaks of respiratory pathogens on hospital wards present a major challenge for control of hospital-acquired infections. When illness presentation is mild or infection is asymptomatic, isolation of recognised cases may be insufficient to prevent outbreaks, as unrecognised cases may be common. In such scenarios, structural controls such as the design of wards with single-occupancy patient rooms, or routine precautions such as the use of N95 respirators by healthcare staff can play an important role in preventing and mitigating outbreaks. Methods This study applies an agent-based extension of the Wells-Riley model of airborne pathogen exposure to simulate COVID-19 outbreaks on hospital wards. We simulated the impact of single-vs. double-occupancy patient rooms on secondary attack rates and the sizes of outbreaks resulting from introduction of unrecognised cases. We further simulated the impact of N95 respirator use by nurses during patient care activities, assuming an efficacy of 90% for protection and source control. Results In our simulations, the size of outbreaks recorded at day 14 was markedly lower in wards with only single-occupancy rooms, compared to double-occupancy rooms (with means of 15.2 and 25.1 infections, respectively). We found that nurses working on wards were more likely to acquire infection than patients. Higher patient room occupancy was associated with increased outbreak size, with a larger relative impact on patients than staff. N95 respirators were effective at mitigating outbreaks, with higher impacts in wards with single-occupancy patient rooms. Conclusions Single-occupancy rooms can greatly decrease the risk of hospital acquired airborne infection for patients. We show that single-occupancy hospital rooms can also reduce the number of healthcare workers infected during an outbreak of an airborne respiratory virus, but not to the same relative extent as patients. Due to the structural constraints limiting transmission between patients in different rooms, outbreaks were driven by transmission events involving nurses, which were effectively mitigated through the use of N95 respirators. Taken together, our results suggest that single-occupancy rooms are effective at reducing outbreak sizes. However, they are insufficient by themselves to prevent large outbreaks without mitigation efforts focused on limiting the potential for transmission involving healthcare workers, such as the use of N95 respirators.

Objective: Clostridioides difficile infection (CDI) is the commonest cause of healthcare-associated diarrhea and undergoes standardized surveillance and mandatory reporting in most Australian states and territories. Historically attributed to nosocomial spread, local and international whole genome sequencing (WGS) data suggest varied sources of acquisition. This study describes C. difficile genotypes isolated at a tertiary center in Melbourne, Australia, their likely source of acquisition, and common risk factors. Design: Retrospective observational study. Setting: The Royal Melbourne Hospital (RMH), a 570-bed tertiary center in Victoria, Australia. Methods: Short-read whole genome sequencing was performed on 75 out of 137 C. difficile isolates obtained from 1/5/2021 to 28/2/2022 and compared to previous data from 8/11/2015 to 1/11/2016. Existing data from infection control surveillance and electronic medical records were used for epidemiological and risk factor analysis. Results: Eighty-five (62.1%) of the 137 cases were defined as healthcare-associated from epidemiological data. On genome sequencing, 33 different multi-locus sequence type (MLST) subtypes were identified, with changes in population structure compared to the 2015–16 period. Risk factors for CDI were present in 130 (94.9%) cases, including 108 (78.8%) on antibiotics, 86 (62.8%) on acid suppression therapy, and 25 (18.2) on chemotherapy. Conclusion: In both study periods, most C. difficile isolates were not closely related, suggesting varied sources of acquisition and that spread of C. difficile within the hospital was unlikely. Current infection control precautions may therefore warrant review. Underlying risk factors for CDI were common and may contribute to the proportion of healthcare-associated infections in the absence of proven hospital transmission.

Background COVID-19 has resulted in many infections in 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 Victorian dataset including community and healthcare cases. Facilities provided standardised epidemiological data and putative transmission links. Findings Between March and October 2020, approximately 1,240 HCW COVID-19 infection cases were identified; 765 are included here. 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 individual patients including super-spreading events. 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.