Antimicrobial resistance in dairy slurry tanks: A critical point for measurement and control.

Waste from dairy production is one of the largest sources of contamination from antimicrobial resistant bacteria (ARB) and genes (ARGs) in many parts of the world. However, studies to date do not provide necessary evidence to inform antimicrobial resistance (AMR) countermeasures. We undertook a detailed, interdisciplinary, longitudinal analysis of dairy slurry waste. The slurry contained a population of ARB and ARGs, with resistances to current, historical and never-used on-farm antibiotics; resistances were associated with Gram-negative and Gram-positive bacteria and mobile elements (ISEcp1, Tn916, Tn21-family transposons). Modelling and experimental work suggested that these populations are in dynamic equilibrium, with microbial death balanced by fresh input. Consequently, storing slurry without further waste input for at least 60 days was predicted to reduce ARB spread onto land, with > 99 % reduction in cephalosporin resistant Escherichia coli. The model also indicated that for farms with low antibiotic use, further reductions are unlikely to reduce AMR further. We conclude that the slurry tank is a critical point for measurement and control of AMR, and that actions to limit the spread of AMR from dairy waste should combine responsible antibiotic use, including low total quantity, avoidance of human critical antibiotics, and choosing antibiotics with shorter half-lives, coupled with appropriate slurry storage.

Are 3D printed models acceptable in assessment?

BACKGROUND: Three-dimensional (3D) printed models are increasingly used in undergraduate anatomy teaching. However, their role and value in anatomy assessment remains under consideration. The aim of this study was to evaluate student and educator perspectives on acceptability of using novel 3D printed heart models for assessment. METHODS: We used printed 3D models of the heart for first-year medical students, in small group teaching, formative assessment and revision at home. We adopted a mixed methods approach involving questionnaires, then focus groups to collect student and educator views. We used QSR Nvivo to manage thematic analysis of responses, carried out by student and educators, respectively. FINDINGS: Overall, students 89% (n = 75/84) and educators 91% (n = 10/11) found the assessment acceptable. Thematic analysis of focus groups (n = 4 students, n = 5 educators) identified five key perceptions shared across student and educator groups: 3D models are the future, realism is valued, models appear feasible, consistent and provide a potential for a range of applications in assessment. DISCUSSION: There was agreement between educators and students that the use of 3D heart models was acceptable. Key recognised benefits include accessibility and consistency across settings, made more relevant in the current COVID-19 pandemic. We recommend integration of 3D models into teaching and assessment for educational alignment and careful selection of anatomy to model. Further research is required to explore the use of models in summative assessments.

Laboratory Stock Variants of the Archetype Silver Resistance Plasmid pMG101 Demonstrate Plasmid Fusion, Loss of Transmissibility, and Transposition of Tn7/pco/sil Into the Host Chromosome.

Salmonella Typhimurium carrying the multidrug resistance (MDR) plasmid pMG101 was isolated from three burns patients in Boston United States in 1973. pMG101 was transferrable into other Salmonella spp. and Escherichia coli hosts and carried what was a novel and unusual combination of AMR genes and silver resistance. Previously published short-read DNA sequence of pMG101 showed that it was a 183.5Kb IncHI plasmid, where a Tn7-mediated transposition of pco/sil resistance genes into the chromosome of the E. coli K-12 J53 host strain had occurred. We noticed differences in streptomycin resistance and plasmid size between two stocks of E. coli K-12 J53 pMG101 we possessed, which had been obtained from two different laboratories (pMG101-A and pMG101-B). Long-read sequencing (PacBio) of the two strains unexpectedly revealed plasmid and chromosomal rearrangements in both. pMG101-A is a non-transmissible 383Kb closed-circular plasmid consisting of an IncHI2 plasmid sequence fused to an IncFI/FIIA plasmid. pMG101-B is a mobile closed-circular 154 Kb IncFI/FIIA plasmid. Sequence identity of pMG101-B with the fused IncFI/IncFIIA region of pMG101-A was >99%. Assembled host sequence reads of pMG101-B showed Tn7-mediated transposition of pco/sil into the E. coli J53 chromosome between yhiM and yhiN. Long read sequence data in combination with laboratory experiments have demonstrated large scale changes in pMG101. Loss of conjugation function and movement of resistance genes into the chromosome suggest that even under long-term laboratory storage, mobile genetic elements such as transposons and insertion sequences can drive the evolution of plasmids and host. This study emphasises the importance of utilising long read sequencing technologies of plasmids and host strains at the earliest opportunity.

Right ventricular sex differences in patients with idiopathic pulmonary arterial hypertension characterised by magnetic resonance imaging: pair-matched case controlled study.

PURPOSE: Sex differences exist in both the prevalence and survival of patients with idiopathic pulmonary arterial hypertension (IPAH). Men are less frequently affected by the condition but have worse outcome as compared to females. We sought to characterise the sex related differences in right ventricular remodelling in age matched male and female patients with IPAH using cardiac magnetic resonance imaging (MRI). METHODS: A case controlled pair-matched study was conducted with patients matched by age and sex. Steady state free precession (SSFP) MRI of the heart was performed at 1.5T. Cardiac volume, function and mass measurements were corrected for age, sex and BSA according to reference data. RESULTS: 40 age and sex matched patients with IPAH were identified. The mean age was 57 (SD 17) in both male and female cohorts. Men had proportionally lower right ventricular (RV) ejection fraction, RV stroke volume and LV stroke volume than females, p=0.028, p=0.007 and p=0.013, respectively. However, there was no significant difference in RV mass or haemodynamic indices of mPAP and PVR between males and females. CONCLUSION: Male patients with IPAH have proportionally worse RV function despite similar afterload. We hypothesise that adaptive remodelling of the RV in response to increased afterload in IPAH is more effective in females.

Preformed silos versus traditional abdominal wall closure in gastroschisis: 163 infants at a single institution.

INTRODUCTION: The surgical management of gastroschisis (GS) is controversial. The most commonly used strategy for abdominal wall closure is surgery on day 1 of life with the aim of primary closure (PC) or construction of a surgical silo (SS) and secondary closure thereafter. The other widely used technique is application of a preformed silo (PFS) and reduction of contents over a few days before final closure. There is still a paucity of comparative outcome data. METHODS: A retrospective case note review of all infants initially treated at a single institution between October 1993 and October 2012. PFS was adopted as the technique of choice in April 2005. Infants with closed or closing GS were excluded. Data are presented as median (range). p < 0.05 were significant. RESULTS: There were 163 infants (156 complete data sets). PFSs were applied in 67 infants and PC/SS were applied in 89 infants of whom 19 infants required a SS. There was no statistical difference between gestational age (p = 0.8), birth weight (p = 0.7), time to first (p = 0.07) and full enteral feeding (p = 0.08), length of hospital stay (p = 0.17), or necrotizing enterocolitis (p = 0.4) and mortality (p = 0.4). Infants treated with PC + SS were closed on day 0 (range, 0-11 days) versus day 6 (range, 2-22 days) of life (p < 0.001). PC + SS were ventilated for day 5 (range, 1-22 days) versus day 3.5 (range, 0-20 days) days (p = 0.01). CONCLUSION: Infants treated with PFS required less ventilation than those treated by PC + SS. There was no difference in time to full feeds, length of hospital stay mortality or morbidity.