Repeated transmission of SARS-CoV-2 in an overcrowded Irish emergency department elucidated by whole-genome sequencing

AIM

To provide a detailed genomic-epidemiological description of a complex multi-ward SARS-CoV-2 outbreak, which originated in the crowded emergency department (ED) in our hospital during the third wave of the COVID-19 pandemic, and was elucidated promptly by local whole-genome sequencing (WGS).

METHODS

SARS-CoV-2 was detected by reverse transcriptase real-time polymerase chain reaction on viral RNA extracted from nasopharyngeal swabs. WGS was performed using an Oxford MinION Mk1C instrument following the ARTIC v3 sequencing protocol. High-quality consensus genomes were assembled with the artic-ncov2019 bioinformatics pipeline and viral phylogenetic trees were built, inferred by maximum-likelihood. Clusters were defined using a threshold of 0-1 single nucleotide polymorphisms (SNPs) between epidemiologically linked sequences.

RESULTS

In April 2021, outbreaks of COVID-19 were declared on two wards at University Hospital Limerick after 4 healthcare-associated SARS-CoV-2 infections were detected by post-admission surveillance testing. Contact tracing identified 12 further connected cases; all with direct or indirect links to the ED 'COVID Zone'. All sequences were assigned to the Pangolin B.1.1.7 lineage by WGS, and SNP-level analysis revealed two distinct but simultaneous clusters of infections. Repeated transmission in the ED was demonstrated, involving patients accommodated on trolleys in crowded areas, resulting in multiple generations of infections across three inpatient hospital wards and subsequently to the local community. These findings informed mitigation efforts to prevent cross-transmission in the ED.

CONCLUSION

Cross-transmission of SARS-CoV-2 occurred repeatedly in an overcrowded emergency department. Viral WGS elucidated complex viral transmission networks in our hospital and informed infection, prevention and control practice.

Selective epicardial pulsed field ablation of atrial ganglionated plexi causes anti-arrhythmic prolongation of refractoriness: demonstration of feasibility in cardiac surgery patients

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): EU Horizon 2020 SME Instrument.

Background

Epicardial ganglionated plexi (GP) play a significant role in the initiation and maintenance of atrial fibrillation. However, modulation of this effect, through GP ablation, has had limited success; outcomes being confounded by unnecessary atrial tissue ablation and inability to access and ablate all of the atrial GPs. Selective pulsed field ablation (PFA) of GPs, using epicardial access, provides the opportunity to better identify the role of GP ablation in the treatment of atrial fibrillation.

Purpose

This study aimed to assess the safety and feasibility of selective GP ablation in patients undergoing elective coronary artery bypass grafting (CABG). It was hypothesized that GP ablation would provide an acute extension of atrial tissue refractoriness, which constitutes its antiarrhythmic effect.

Methods

Using a monopolar, monophasic PFA system, atrial GPs were ablated in nineteen patients with or without atrial fibrillation, undergoing CABG. The Oblique Sinus GP, Right Superior GP, Transverse Sinus GP, Left Superior GP and Ligament of Marshall GP were each ablated with up to sixty PFA pulses of 1000 V amplitude and 100 µs pulse width. Atrial Effective Refractory Period (AERP) was measured before and after all GP ablations, at the left atrial appendage (LAA) and on the right atrium (RA). Patients were monitored through to discharge for post-operative atrial fibrillation (POAF).

Results

Complete ablation of the GPs was performed in nineteen patients (aged 63.4 ± 6.6 years, 63.1% male) immediately after sternotomy. Electric field pulses were ECG-gated, with energy delivery during the ventricular refractory period. All GP sites were successfully accessed and ablated; all patients progressed immediately to their planned elective surgery and were discharged on schedule. Procedure time, for all GP ablations and AERP measurements was in the range 35-45 minutes. Thirteen valid pre- and post-ablation datasets were obtained. AERP (LAA and RA combined) increased upon GP ablation on average by 23% (220 ± 46 ms pre-ablation versus 269 ± 59 ms post-ablation, p = 0.002). Four patients experienced POAF; there was no evident correlation between POAF and AERP data. Only three of the enrolled patients had a prior history of AF; none of these exhibited AF on 24-hour Holter monitoring at 3-month follow-up.

Conclusions

Selective epicardial PFA of GPs is feasible and safe. An acute increase in atrial tissue refractoriness is promising but further studies are required to see how this translates to longer term outcomes in symptomatic AF patients and in a percutaneous epicardial access setting.

The effect of fertilizer nitrogen input to grass-clover swards and calving date on the productivity of pasture-based dairy production

The objective of this systems-scale study was to investigate grazing season timeframes on pasture and milk production and on milk processability of dairy systems with compact spring-calving dairy cows grazing white clover (Trifolium repens L.) based grassland. Fifty-four primiparous and multiparous Holstein-Friesian dairy cows were used in a one-factor study with 3 systems (n = 18) and repeated over 2 yr (2008/09 and 2009/10). The 3 systems were: early spring calving with annual fertilizer N input of 100 kg·ha^-1 applied in spring (ES100N; 2.1 cows·ha^-1; grazing February to November), early spring calving without fertilizer N (ES0N; 1.6 cows·ha^-1; grazing February to November) and late spring calving without fertilizer N (LS0N; 1.53 cows·ha^-1; grazing April to January). Annual pasture production was affected by an interaction between grazing system and year: Mean annual pasture yields for 2008 and 2009 were ES100N; 10.35 and 9.88, ES0N; 8.88 and 8.63, LS0N; 9.18 and 10.31 t of dry matter (DM)·ha^-1 (SEM 0.39). LS0N had higher pasture DM yield in 2009 due to higher clover DM production and biological N fixation compared with the other systems. Clover stolon and root mass in the following February was correlated with stolon and root mass in the previous November with 64% of stolon mass present on LS0N in February (R² = 0.84). There were no detectable differences in per-lactation milk yield (6,335 kg·cow^-1), fat, protein and lactose yields (271, 226, 297 kg·cow^-1, respectively), cow liveweight (585 kg) or body condition score (3.02). Although winter grazing favored subsequent clover DM production, biological N fixation and pasture DM production, delaying calving date in spring and extending lactation into the following winter led to inefficient use of this pasture by the grazing herd and lowered the quality of late-lactation milk for processing purposes. Hence, a mean calving date in mid- to late-February is recommended for zero-fertilizer N input clover-based grassland.

The impact of intraoperative transoesophageal echocardiography on decision-making during cardiac surgery

BACKGROUND

Real time intraoperative transoesophageal echocardiograpgy (TOE) has an expanding role in peri-operative management and surgical decision making.

OBJECTIVES

Studies of the effect of transoesophageal echocardiography (TOE) on intraoperative decision making commonly emphasise major changes in operative plans. We examined more subtle effects using a novel scale, recording influences on management as follows: Level 1: TOE had no effect on management, confirmed and quantified known pathology. Level 2: TOE altered hemodynamic and/or anesthetic management. Level 3: TOE evaluated the adequacy of surgical intervention/or repair. Level 4: TOE led to an alteration in the surgical plan. We compared the impact of TOE as an aid to intra-operative management in coronary artery bypass cases with other types of cardiac surgery.

METHODS

Retrospective, observational study in a single centre, university-affiliated hospital included 319 patients undergoing cardiac surgery and suitable for TOE. TOE was performed in each patient before and after the institution of cardiopulmonary by-pass. Normal and abnormal echocardiographic findings as well as immediate outcomes of the surgical procedure were recorded using a standard database form. Instances where TOE lead to alteration in operative management were documented. The findings were also compared with those documented on preoperative echocardiography.

RESULTS

In 141 CABG patients TOE had a level 1 impact in 73%, level 2 impact in 11.6%, levels 3 and 4 in 7% and 7.8% respectively. In 178 non CABG patients these values were 2%, 1.6%, (p < 0.05), 72.4% (p < 0.05) and 23.6% (p < 0.05) respectively.

CONCLUSION

The impact of TOE in CABG procedures, while significantly less than that in non-CABG surgical procedures, remains substantial.