HOW GOOD BACTERIA GO BAD

 

Bacteria can evolve rapidly to adapt to environmental change. When the "environment" is the immune response of an infected host, this evolution can turn harmless bacteria into life-threatening pathogens.

 

 

What Makes Good Bacteria Go Bad?
It's Not Them, It's You

 

Colonies of Streptococcus pneumoniae bacteria (aka pneumococcus) can camp out happily and harmlessly for months at a time in the nose and throats of humans, then abruptly turn on their hosts. The germs sometimes trigger painful earaches or even meningitis in kids, and often pneumonia in the elderly and others with weak immune systems.

 

It's no small problem. The World Health Organization calls diseases triggered by the microbe "a major global public health problem." In 2000 alone pneumococcus provoked an estimated 14.5 million bouts of serious illness worldwide, according to the WHO, and killed perhaps 826,000 children under the age of 5.

 

At any given time, between 25 and 40 percent of children under age 5 are colonized with the bacteria, and between 8 and 15 percent of adults. Typically, these bacterial campsites persist for a few days, weeks or months, and don't produce symptoms.

Anders Hakansson, a microbiologist at the State University of New York at Buffalo and his team may have figured out how people get sick  .In a cool bit of science they recently published in the journal mBio, the researchers describe how they created a microbial community in a lab dish that mimics what happens in the lining of the human nose and upper throat.

 
Source - http://www.npr.org/blogs/health/2013/08/07/209794356/what-makes-good-bacteria-go-bad-its-not-them-its-you
 

From Friend to Foe: How Benign Bacteria

Evolve Into Virulent Pathogens

 

Isabel Gordo and colleagues from the Instituto Gulbenkian de Ciencia in Oeira, Portugal, have for the first time devised an experimental system to observe and study the evolution of bacteria in response to encounters with cells of the mammalian immune system.

They found that in less than 500 bacterial generations (or 30 days), the bacteria became more resistant to being killed by immune cells and acquired the ability to cause disease in mice.

 

For their study, the scientists studied initially benign E. coli bacteria that were continuously confronted with macrophages, which are part of our immune system and can swallow and digest bacteria.

 

From day four on, bacteria that had been exposed to macrophages started to show changes in their phenotype (their appearance), whereas such changes were never observed in the controls.

 

When the scientists looked at the interaction between new variant bacteria and macrophages more closely, they found that the small colony variants were more resistant to being digested by macrophages than the ancestral strain, and the mucoid variant was less likely to be gobbled up.

 

When they infected mice with mucoid variant bacteria, they also found that the variants have increased ability to cause disease in mice.

Read more  - http://www.sciencedaily.com/releases/2013/12/131212185831.htm


More items about microbes on this blog -
http://ottersandsciencenews.blogspot.ca/search/label/Microbes


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