TeachableMedicalNews article 09292022

Teachable moment in classrooms:

  1. cellular basis of life chapter – linker proteins in the plasma membrane form tight junctions
  2. tissue chapter – tight junctions of epithelial cells prevent movement of pathogens between the cells
  3. immune system chapter – reliance of white blood cells for immune functions
  4. brain chapter – the brain is covered by meninges inside the cranial cavity
  5. microbiology – the pathogen bacterium Chronobacter sakazakii

The news item:  Recently a news report appeared about contaminated baby formula:

FDA says maker of powdered infant formula didn’t take steps to prevent products from becoming contaminated | CNN

The US Food and Drug Administration (FDA) has determined the company running a plant at the center of a baby formula recall didn’t take steps to prevent products from becoming contaminated during manufacturing, according to a preliminary report filed this month.

The article states that Chronobacter sakazakii bacterium caused death of two infants who used baby formula contaminated with the bacterium.

So, Why Do I Care??  While adults can easily defeat a bacterial infection, the bodies of infants are very vulnerable to such infection.  Because the immune system of infants is naturally weak, powdered infant formulas must be free of bacterial contamination. If bacteria are in the infant formula, then the infants are exposed to life threatening infection.  The number of infections is about 15 infants each year, but one-fourth of the infants die from the infection.

Plain English, Please!!!  First, let’s talk about what a Chronobacterium is. This is a very common bacterium in environment, present on many surfaces and in food items. The well-trained immune system of adults can fight off this bacterium, but the not-yet-fully developed immune system of infants has a difficulty in defeating the Chronobacter infection.  This is why sterilization of infant formula is done routinely during the manufacturing process.

Second, let’s talk about how Chronobacterium causes disorders. The ingested Chronobacterium (drinking contaminated baby formula, in this example) sticks to the cell lining the small intestine, and degrade the material that holds neighboring cell together. Imagine a brick chimney where the mortar between the bricks hold the entire structure together. The mortar between the cells of the small intestine is made of linker proteins that create the barrier, the “tight junction”.  When the mortar erodes from the chimney, the bricks come loose. Chronobacter degrades the linker proteins, and, thus, erodes the tight junctions, so the cells now have gaps between them, and the bacteria can move into the bloodstream by sneaking through the gaps between the cells. The neutrophil white blood cells of the infant’s immune system are not fully functional, and they cannot  destroy the bacteria invading the small intestine

Third, let’s talk about the life threatening consequences of Chronobacterium infection. On the site of infection in the small intestine Chronobacter causes necrotizing enterocolitis which destroys the wall of the small intestine allowing the spread of the bacteria into the bloodstream.  Once in the blood Chronobacter most frequently sicks to and infects the meninges, the membrane-like cover of the brain and spinal cord.  The attack causes meningitis which damages the brain, making meningitis the most frequent cause of death among infected infants.

 

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