Browsing by Author "Phair, Katie"
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- Insights into the mechanisms of Cronobacter sakazakii virulencePublication . Phair, Katie; Pereira, Sónia Gonçalves; Kealey, Carmel; Fanning, Séamus; Brady, Damien B.Cronobacter species have adapted to survive harsh conditions, particularly in the food manufacture environment, and can cause life-threatening infections in susceptible hosts. These opportunistic pathogens employ a multitude of mechanisms to aid their virulence throughout three key stages: environmental persistence, infection strategy, and systemic persistence in the human host. Environmental persistence is aided by the formation of biofilms, development of subpopulations, and high tolerance to environmental stressors. Successful infection in the human host involves several mechanisms such as protein secretion, motility, quorum sensing, colonisation, and translocation. Survival inside the host is achieved via competitive acquisition and utilization of minerals and metabolites respectively, coupled with host immune system evasion and antimicrobial resistance (AMR) mechanisms. Across the globe, Cronobacter sakazakii is associated with often fatal systemic infections in populations including neonates, infants, the elderly and the immunocompromised. By providing insight into the mechanisms of virulence utilised by this pathogen across these three stages, this review identifies current gaps in the literature. Further research into these virulence mechanisms is required to inform novel mitigation measures to improve global food safety with regards to this food-borne pathogen.
- Pre-Exposure to α-Linolenic Acid Reduces Virulence of Cronobacter sakazakii in Galleria mellonella Infection ModelPublication . Phair, Katie; Curtis, Aaron; Pereira, Sónia G.; Kealey, Carmel; Kavanagh, Kevin; Brady, DamienCronobacter sakazakii is a food-borne pathogen with infections notifiable in those under 12 months old. Current inhibition methods rely on manufacture and reconstitution guidelines. Fatty acids (FA) are a possible method of control, with reports showing FAs can be bactericidal and regulate virulence mechanisms such as biofilm formation. This research explores the efficacy of the long-chain FA α-linolenic (ALA) to reduce C. sakazakii virulence in vivo. Galleria mellonella larvae were injected with FA pre-treated C. sakazakii and viability monitored every 24 h over a total of 96 h. To show the interaction between the host immune system and C. sakazakii, haemocytes and bacterial cells were mixed and enumerated following incubation. To investigate the impact on antimicrobial resistance (AMR), 24 antibiotics were tested against C. sakazakii pretreated with ALA. Kaplan–Meier survival curves generated showed a dose-dependent increase in larval survival upon increased FA concentration. Regarding the immune evasion assay, data generated show increased C. sakazakii and decreased haemocyte counts in the same sample. From the AMR results, there was no statistically significant difference in inhibition zones when compared to the control, indicating no contraindications for current treatment options. α-linolenic acid is a common component of the human diet and is shown here to directly reduce virulence mechanisms including immune system evasion. Pre-treatment with ALA reduces the virulence of C. sakazakii, resulting in increased survival of G. mellonella larvae. This suggests that ALA may serve as a candidate for further evaluation as a potential agent against C. sakazakii.