TeachableMedicalNews article 02272022

Teachable moment in classrooms:

  1. microbiology – Burkholderia bacteria
  2. microbiology – bacterial movement by flagella
  3. cellular basis of life chapter – lysosomes can digest invaders, or self-digest a cell during autophagy cell death
  4. tissue chapter – cells of epithelial tissue line the lumen of respiratory and digestive systems
  5. immune system chapter – neutrophils and other white blood cells phagocytose invaders
  6. blood vessel chapter – septic shock suppresses blood pressure by causing vasodilation

The news item:  Recently the following news report appeared online:

Mysterious fatal infections tied to room spray sold at Walmart

Federal authorities warned Friday that a rare bacterial infection that killed two people has been tied to an aromatherapy spray sold at Walmart. A total of four people in four states were infected earlier this year by the rare tropical disease called melioidosis.

The article stated that four victims of melioidosis were identified in the US, that the disease is caused by Burkholderia pseudomallei bacterium, that the bacterium lives in soils in Southeast Asia, and that the pathogens were traced to aroma therapy spray bottles.

So, Why Do I Care??  Infectious pathogens are found in many locations, and they can cause deadly diseases. In addition to the well-know viruses and bacteria, there are exotic pathogens that cause rare, but just as deadly infections. Therefore, it is important to understand how those exotic pathogens act. Melioidosis has a 50% death rate, and even after antibiotic treatment the death rate remains 10%.

Plain English, Please!!! First, let’s talk about how this bacterium infects our body. The bacteria enter the body through inhaling or ingesting contaminated water. The bacterium then moves into the epithelial cells that line the lumen of the lower respiratory or the epithelial cells that line the lumen of digestive system. Once inside the host cell, the bacterium deploys proteins that allow it to avoid digestion by the lysosomes of the host cell, and proteins that prevent the self-digestion (autophagy) death of the host cells. After multiplying in the cytoplasm, this bacterium can move into neighboring host cells or into the blood stream by the help of its flagella. In this fashion the bacterium stays largely hidden from our immune system as it moves on to infect the entire lung, to infect neurons to spread into the brain, and phagocytic white blood cells, such as neutrophils.

Second, let’s talk about how melioidosis causes deadly damage to our body. By hiding from our immune system inside our cells, spreading through tissues, entering into bloodstream, and by slowing the immune response, Burkholderia pseudomallei infection causes wide range of damage. In the lungs bacterial pneumonia develops resulting in respiratory distress. In the brain encephalitis develops. In the blood sepsis develops, and the bacterial toxins in the blood cause multi-organ malfunction and failure.  Many locations in the body develop abscesses, where the neutrophils impaired by their infection are fighting to stop the spread of the bacteria.   From all these locations bacterial toxins will enter the blood, and reprogram the smooth muscles of blood vessels. Imagine that blood vessels have waistband-like smooth muscle cells that keep blood vessels narrow to produce normal blood pressure. The bacterial toxins instruct smooth muscle cells to relax, the belt becomes more loose, and the blood vessel becomes wider.  That widening is called vasodilation, an action that brings about low blood pressure.  In infected patients blood pressure can cause fainting, and coma.

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