These guts from a newborn mouse show just how vulnerable young mammals can be to infectious bacteria. Often found in contaminated food, Salmonella (shown in red) have worked their way from the mouse’s mouth to its small intestine. Just as many of the newborn’s tissues and organs are still developing so too are the defences which protect them from outside threats. Here the layers of chemicals and cells that guard adult intestines – the mucosal barrier – are still in their infancy and prone to attack. Jumping through this barrier, Salmonella have invaded the endocyte cells which line the intestine (outlined in white with their nuclei in blue) and may spread to other organs. Salmonella infection in humans is a major cause of diarrhoeal disease and even meningitis, responsible for many infant deaths. Understanding how our bacterial defences develop is crucial to guiding both new medicines and supporting hygiene programs worldwide.
Written by John Ankers
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