Endoscopies, blood-borne viruses and blood donors: time to move on from precaution.

BACKGROUND AND OBJECTIVES: Based on the Council of Europe directive which dictates regulatory requirements in Australia, blood donors are currently deferred from donating for 4 months after an endoscopic procedure if either polyps were removed or a biopsy sample was taken. We aimed to assess the incidence of blood-borne viruses (BBVs) (HIV, hepatitis B and C) in blood donors who donated after an endoscopic procedure and evaluate the risk to blood safety through risk modelling. MATERIALS AND METHODS: Donors from 1/1/2013 to 31/12/2017 with an endoscopy deferral on their blood donor file with pre- and post-BBV testing were analysed to determine an incidence of BBVs using standard methods. The standard blood donor cohort was used as a comparator group. Using the incidence of endoscopies and BBV risk, the total residual risk estimate of allowing donors to return postendoscopy without restriction was calculated. RESULTS: The incidence of a BBV postendoscopy in this large cohort of 16,283 where testing has been confirmed postendoscopy was zero (95% CI 0-0·000105). The upper confidence interval of the zero events is 10·5 per 100 000 donations. Total positive donations from 2017 repeat donors were 1·87 per 100 000 (95% CI 0·0000117-0·0000277). Sensitivity analysis demonstrated that the residual risk remained negligible under realistic worst-case scenarios. CONCLUSION: A BBV endoscopy deferral is not required for blood safety in Australia. The presented data has enabled us to submit a request for an exemption to our regulator, which has been approved and the policy change subsequently implemented by Lifeblood on 4/4/2020.

The polyene antifungals, amphotericin B and nystatin, cause cell death in Saccharomyces cerevisiae by a distinct mechanism to amphibian-derived antimicrobial peptides.

BACKGROUND: There is a pressing need to identify novel antifungal drug targets to aid in the therapy of life-threatening mycoses and overcome increasing drug resistance. Identifying specific mechanisms of action of membrane-interacting antimicrobial drugs on the model fungus Saccharomyces cerevisiae is one avenue towards addressing this issue. The S. cerevisiae deletion mutants Δizh2, Δizh3, Δaif1 and Δstm1 were demonstrated to be resistant to amphibian-derived antimicrobial peptides (AMPs). The purpose of this study was to examine whether AMPs and polyene antifungals have a similar mode of action; this was done by comparing the relative tolerance of the mutants listed above to both classes of antifungal. FINDINGS: In support of previous findings on solid media it was shown that Δizh2 and Δizh3 mutants had increased resistance to both amphotericin B (1-2 µg ml-1) and nystatin (2.5 - 5 µg ml-1) in liquid culture, after acute exposure. However, Δaif1 and Δstm1 had wild-type levels of susceptibility to these polyenes. The generation of reactive oxygen species (ROS) after exposure to amphotericin B was also reduced in Δizh2 and Δizh3. These data indicated that polyene antifungal and AMPs may act via distinct mechanisms of inducing cell death in S. cerevisiae. CONCLUSIONS: Further understanding of the mechanism(s) involved in causing cell death and the roles of IZH2 and IZH3 in drug susceptibility may help to inform improved drug design and treatment of fungal pathogens.