Nosocomial Transmission of SARS-CoV-2 Involving Vaccinated Health Care Workers

COVID-19 vaccination has proven to be effective at preventing symptomatic disease but there are scarce data to fully understand whether vaccinated individuals can still behave as SARS-CoV-2 transmission vectors. Based on viral genome sequencing and detailed epidemiological interviews, we report a nosocomial transmission event involving two vaccinated health care-workers (HCWs) and four patients, one of them with fatal outcome.

Genomic dissection of the bacterial population underlying Klebsiella pneumoniae infections in hospital patients: insights into an opportunistic pathogen

Klebsiella pneumoniae is a major cause of opportunistic healthcare-associated infections, which are increasingly complicated by the presence of extended-spectrum beta-lactamases (ESBLs) and carbapenem resistance. We conducted a year-long prospective surveillance study of K. pneumoniae clinical isolates identified in a hospital microbiological diagnostic laboratory. Disease burden was two-thirds urinary tract infections (UTI; associated with female sex and age), followed by pneumonia (15%), wound (10%) and disseminated infections/sepsis (10%). Whole-genome sequencing (WGS) revealed a diverse pathogen population, including other species within the K. pneumoniae complex (18%). Several infections were caused by K. variicola/K. pneumoniae species hybrids, one of which showed evidence of nosocomial transmission, indicating fitness to transmit and cause disease despite a lack of acquired antimicrobial resistance (AMR). A wide range of AMR phenotypes were observed and, in most cases, corresponding mechanisms were identified in the genomes, mainly in the form of plasmid-borne genes. ESBLs were correlated with presence of other acquired AMR genes (median 10). Bacterial genomic features associated with nosocomial onset of disease were ESBL genes (OR 2.34, p=0.015) and rhamnose-positive capsules (OR 3.12, p<0.001). Virulence plasmid-encoded features (aerobactin, hypermucoidy) were rare (<3%), and mostly present in community-onset cases. WGS-confirmed nosocomial transmission was rare (10% of cases) but strongly associated with ESBLs (OR 21, p<1x10-11). We estimate 28% risk of onward nosocomial transmission for ESBL-positive strains vs 1.7% for ESBL-negative strains. These data indicate the underlying burden of K. pneumoniae disease in hospitalised patients is due largely to opportunistic infections with diverse strains. However, we also identified several successful lineages that were overrepresented but not due to nosocomial transmission. These lineages were associated with ESBL, yersiniabactin, mannose+ K loci and rhamnose- K loci; most are also common in public clinical genome collections, suggesting enhanced propensity for colonisation and spread in the human population.

Evaluation of the ImmuView RSV Test for Rapid Detection of Respiratory Syncytial Virus in Adult Patients with Influenza-Like Symptoms

By timely RSV diagnosis among patients with influenza-like symptoms, especially when influenza diagnostics turn negative, it is possible to prevent unnecessary antibiotic usage as well as reduce diagnostic testing, nosocomial transmission, and hospital stay. Previous rapid RSV tests have demonstrated poor sensitivity in adults, and we could demonstrate that the novel ImmuView RSV test similarly showed limited value for diagnosing RSV infection in adult patients.

Evaluating the potential for respiratory metagenomics to improve treatment of secondary infection and detection of nosocomial transmission on expanded COVID-19 intensive care units

Background Clinical metagenomics (CMg) has the potential to be translated from a research tool into routine service to improve antimicrobial treatment and infection control decisions. The SARS-CoV-2 pandemic provides added impetus to realise these benefits, given the increased risk of secondary infection and nosocomial transmission of multi-drug-resistant (MDR) pathogens linked with the expansion of critical care capacity. Methods CMg using nanopore sequencing was evaluated in a proof-of-concept study on 43 respiratory samples from 34 intubated patients across seven intensive care units (ICUs) over a 9-week period during the first COVID-19 pandemic wave. Results An 8-h CMg workflow was 92% sensitive (95% CI, 75–99%) and 82% specific (95% CI, 57–96%) for bacterial identification based on culture-positive and culture-negative samples, respectively. CMg sequencing reported the presence or absence of β-lactam-resistant genes carried by Enterobacterales that would modify the initial guideline-recommended antibiotics in every case. CMg was also 100% concordant with quantitative PCR for detecting Aspergillus fumigatus from 4 positive and 39 negative samples. Molecular typing using 24-h sequencing data identified an MDR-K. pneumoniae ST307 outbreak involving 4 patients and an MDR-C. striatum outbreak involving 14 patients across three ICUs. Conclusion CMg testing provides accurate pathogen detection and antibiotic resistance prediction in a same-day laboratory workflow, with assembled genomes available the next day for genomic surveillance. The provision of this technology in a service setting could fundamentally change the multi-disciplinary team approach to managing ICU infections. The potential to improve the initial targeted treatment and rapidly detect unsuspected outbreaks of MDR-pathogens justifies further expedited clinical assessment of CMg.

Efficacy of interventions to reduce nosocomial transmission of SARS-CoV-2 in English NHS Trusts in Wave 1: A computational modelling study

Nosocomial transmission of SARS-CoV-2 has the potential to place a large burden on the healthcare system through, for example, increased patient length of stay, pressure on specialist care capacity and staff shortages. In England, a number of interventions were applied in hospitals over wave 1 of the COVID-19 pandemic to limit the spread of SARS-CoV-2 among both hospital inpatients and healthcare workers (HCWs). Using a computational modelling approach, we have estimated the combined effect of these, and other changes within the hospital setting, to determine how many nosocomial infections were averted. While highly uncertain, due primarily to important gaps in the evidence base, model results suggest that in a scenario with high occupancy, no testing, reduced infection prevention and control (IPC) measures, increased visitors, and longer patient stays, approximately 5.2% (3.9-7.2%) of all susceptible inpatients (n=140,603; 95% CI, 89,352-197,977 patients in total), and 51.1% (43.6, 55.3%) of patient-facing HCWs could have been nosocomially infected with SARS-CoV-2 over wave 1 compared with the 1.0% (0.7, 1.2%) of patients (33,922; 24,089- 41,015) and 20.3% (15.8-29.4%) of HCW observed to be nosocomially infected. The most effective interventions for prevention of nosocomial infections in patients were decreasing occupancy, increasing spacing between beds, and testing patients on admission, resulting in a reduction of 23,434 (14,544, 31,341), 10,979 (2,458, 16,979), and 9,505, (4588, 12,823) infections, respectively. Although every intervention had some impact, it was the collective impact of all interventions that demonstrated greatest effect, averting 140,603 (89,352, 197,977) infections in inpatients. In HCWs, the most effective intervention was universal mask use, with inclusion of universal masking as part of IPC measures averting 46.0% (42.9-54.5%) of infections in HCWs resulting in 17,980 (2,772-28,450) fewer infections per 100,000 patient-facing HCWs. Interventions introduced over wave 1 of the SARS-CoV-2 pandemic in England reduced HCW infection rates by 51.1% (43.6-55.3%).

TP10.2.14Safe elective & emergency surgery: experience of a large tertiary centre during the first wave of the COVID-19 pandemic

Aims To evaluate the impact of Trust infection prevention measures (including relocation of elective patients into a protected cold wing, vigilant testing and staff test and trace) on elective and emergency nosocomial transmission rates and to analyse post-operative mortality in COVID-19 patients. Additionally, we compared the numbers of elective and emergency procedures in 2020 to 2019. Method Retrospective analysis of 5069 consecutive patients who underwent procedures in theatre from 11/03/20 – 08/09/20. COVID-19 infection was defined by PCR and/or radiological confirmation. Analysis of nosocomial transmission of COVID-19 and mortality was conducted using patient notes and death certificates. The number of procedures was compared with the same study dates in 2019. Results Nosocomial transmission rate was 0.27% in elective admissions (10/3773) and 0.97% in acute admissions (20/2052). The overall mortality in 2020 was 2.7% (135/5069). Covid-negative mortality was 2.36% (119/5033). 74 patients tested positive for COVID-19 at any time (1.3%); mortality in patients who tested positive seven days pre- to 30 days post-procedure was 5.4% (4/74). There were 10282 elective procedures in 2019 compared with 3773 in the same period in 2020, representing a 63.3% reduction in elective activity. Conclusion Our hospital infection prevention measures have kept nosocomial transmission rates low, particularly for elective admissions. We have observed lower rates of post-operative mortality in COVID-19 patients than published in other centres. There has been a predictably significant reduction in elective activity, however based on our findings we believe our infection prevention measures could provide reassurances to safely increase elective surgery activity.

Updated Evidence on the Epidemiology of Hepatitis C Virus in Hemodialysis

Prevalence rates of HCV infection are decreasing in hemodialysis units of most developed countries; however, nosocomial transmission of HCV continues to occur in the hemodialysis setting, not only in the emerging world. According to the Dialysis Outcomes and Practice Patterns Study (DOPPS, 2012–2015), the prevalence of HCV among patients on regular hemodialysis was 9.9%; in incident patients, the frequency of HCV was approximately 5%. Outbreaks of HCV have been investigated by epidemiologic and phylogenetic data obtained by sequencing of the HCV genome; no single factor was retrieved as being associated with nosocomial transmission of HCV within hemodialysis units. Transmission of HCV within HD units can be prevented successfully by full compliance with infection control practices; also, antiviral treatment and serologic screening for anti-HCV can be useful in achieving this aim. Infection control practices in hemodialysis units include barrier precautions to prevent exposure to blood-borne pathogens and other procedures specific to the hemodialysis environment. Isolating HCV-infected hemodialysis patients or using dedicated dialysis machines for HCV-infected patients are not currently recommended; reuse of dialyzers of HCV-infected patients should be made, according to recent guidelines. Randomized controlled trials regarding the impact of isolation on the risk of transmission of HCV to hemodialysis patients have not been published to date. At least two studies showed complete elimination of de novo HCV within HD units by implementation of strict infection control practices without isolation practices. De novo HCV within hemodialysis units has been independently associated with facility HCV prevalence, dialysis vintage, and low staff-to-patient ratio. Antiviral treatment of HCV-infected patients on hemodialysis should not replace the implementation of barrier precautions and other routine hemodialysis unit procedures.

A high frequency of Candida auris blood stream infections in COVID-19 patients admitted to intensive care units, North-western India: A case control study

Background The ongoing pandemic of COVID-19 has overwhelmed healthcare facilities raising an important novel concern of nosocomial transmission of Candida species in the intensive care units. Methods We evaluated the incidence and risk factors for development of candidemia in 2384 COVID-19 patients admitted during August 2020-January 2021 in ICUs of two hospitals (Delhi and Jaipur), India. A 1:2 case control matching was used to identify COVID-19 patients who did not develop candidemia as controls. Result A total of 33 patients developed candidemia accounting for an overall incidence of 1.4% over a median ICU stay of 24 days. A two-fold increase in the incidence of candidemia in COVID-19 versus non–COVID-19 patients was observed with an incidence rate of 14 and 15/1000 admissions in two ICUs. Candida auris was the predominant species (42%) followed by Candida tropicalis. Multivariable regression analysis revealed the use of tocilizumab, duration of ICU stay (24 vs. 14 days) and raised ferritin level as an independent predictor for the development of candidemia. Azole resistance was observed in C. auris and C. tropicalis harbouring mutations in the azole target ERG11 gene. MLST identified identical genotypes of C. tropicalis in COVID-19 patients raising concern of nosocomial transmission of resistant strains. Conclusion Secondary bacterial infections has been a concern with the use of tocilizumab. In this cohort of critically ill COVID-19 patients tocilizumab was associated with development of candidemia. Surveillance of antifungal resistance is warranted to prevent transmission of MDR strains of nosocomial yeasts in COVID-19 hospitalised patients.

902 Safe Elective & Emergency Surgery During the COVID-19 Crisis: Experience of a Large Tertiary Centre During the First Wave of the Pandemic

Aim In addition to a reduction in elective surgery, the COVID-19 pandemic has been associated with concerning rates of post-operative mortality in COVID-19 patients highlighting the threat of nosocomial transmission. Relocation of elective patients into a protected cold wing of a tertiary centre, vigilant testing and staff test, and trace were implemented to address these issues. Method Retrospective analysis of 5069 consecutive patients who underwent procedures in theatre from 11/03/20 – 08/09/20 was performed. Comparison of numbers of procedures was compared with the same study dates in 2019. Detailed analysis of nosocomial transmission of COVID-19 and mortality was performed using patient notes and death certificates. Results 5854 procedures were performed in 2020 compared with 13219 in 2019, representing a reduction of 55.7%. The overall mortality in 2020 was 2.7% (135/5069). COVID-19 negative mortality was 2.36% (119/5033). 74 patients tested positive for COVID-19 at any time (1.3%); mortality amongst patients who tested positive seven days pre- to 30 days post-procedure was 5.4% (4/74). Nosocomial transmission rate was 0.27% in elective admissions (10/3773) and 0.97% in acute admissions (20/2052). Conclusions The first wave of the pandemic has predictably caused a significant reduction in elective activity. Our hospital infection prevention measures have kept nosocomial transmission rates low, particularly for elective admissions. We have observed lower rates of post-operative mortality in COVID-19 patients than published in other centres. Continuation of surgical services is important for patient outcomes, and essential for training the surgeons of tomorrow.