WILTIMS #186: Shooting starter colonies

Listeria comet

TIL: Listeria comets are super cool (if you don't have them streaking through your intestinal epithelium). This bacterium likes to live inside the cells of the lining of the gut. It uses a potent one-two punch of toxins to burst through the vesicles that cells use to scoop up and destroy offensive organisms. Once in the cell, listeria hijacks some of the cell's scaffolding machinery and redirects it to quickly polymerize in the direction of the cell membrane. This streak is called a listeria comet and it's so strong that it can puncture the adjacent cell's membrane. From there, the bacterium needs only to reactivate its toxic tools to degrade the lipid layers surrounding it and start the process all over again.

This process allows listeria to spread completely unseen by the body's adaptive immune response, by never needing to exit its cellular hiding place to spread or replicate.

Next, C. difficile infections are almost entirely caused by antibiotics. And by that I don't mean that we are injecting people with bacteria or anything, but rather that a side effect of even the most appropriate antibiotic usage can be a gastrointestinal infection from this annoying (and sometimes deadly) bug. It's weird looking back at incidence rates from before and after widespread antibiotic use, because the correlation is very apparent. In fact, scientists originally hypothesized that the antibiotics themselves were the cause of the diarrhea sometimes seen upon their administration.

C. diff is commonly found in small numbers in a large percentage of the population, but it can never really get a foothold thanks to our existing gut microbiota. The problem arises when we wipe out the healthy bacteria while treating some other infection elsewhere in the body with antibiotics. This gives c. diff the chance it needs to assume a bigger and more pathogenic role in the intestines. 

Lastly, most STDs grew in prevalence from the 60s through the 70s. Then the rates of new infections stopped abruptly in 1980. The reason? Fear of the growing AIDS epidemic forced people into practicing safer sex.