Thursday, October 30, 2014

Lab Acquired Salmonella

An interesting bit of lab saftey news came out awhile back that I think hasn't gotten quite enough attention.
Since November 2013, 41 people in 13 states have been sickened by a Salmonella typhimurium outbreak (enterica serotype).

Salmonella typhimurium (pink)
The Salmonella was linked to clinical and university teaching laboratories according to the CDC investigation.
Cases have been reported in Illinois, Indiana, Kentucky, Maine, Massachusetts, Missouri, New Hampshire, New Jersey, Ohio, Pennsylvania, Virginia, Washington, and Wisconsin. The CDC investigation (probably performed mostly by the PulseNet group) revealed via laboratory testing (pulsed-field gel electrophoresis) sequence from commercially available S. typhimurium strains used in laboratory settings for teaching or quality control purposes. Basically, the S. typhimurium strain infecting people and making them ill was identified by PFGE (seperating DNA in a gel matrix based on a changing electric field), and it was similar to the S. typhimurium that could be acquired commercially.

The S. typhimurium strains are known to be present in several teaching laboratories that were associated with ill people. Epidemiological information gathered showed that 18 of the 21 people infected (86%) were enrolled in either a human biology or microbiology course. 15 of those 18 ill persons were students, and three (22%) were employees.
This is not the first outbreak linked to a college laboratory class, in 2011 a total of 109 illnesses were linked to clinical and microbiology teaching laboratories.
These outbreaks of Salmonella and other lab-associated organisms bring up important points about lab safety in teaching labs.
  • Some of the bacteria you work with can make you and others near you sick. Most of the time, lab-bacterial strains are weak and non pathogenic. However, it is possible that they can still cause illness.
  • It is possible to spread bacteria via contaminated lab coats, pens, keys, phones, mp3 players, notebooks, and other items that go in and out of the laboratory. Avoid taking things in and out of the lab.
  • People who work with infectious agents should be careful to handle samples properly and to wash hands appropriately, especially before you prepare any food, baby bottles, before eating, or contacting young children.
  • Non-pathogenic or attenuated bacterial strains should be used when possible in teaching laboratories.
This is what a microbiology teaching lab looks like.
I am guilty of breaking on some occasion most of these rules. I wear an ipod most days (albeit inside my lab coat). I have definitely eaten and drank in the lab, etc. The main thing to consider is handwashing, and proper handling of organisms. And if you are unsure, it is always better to be safe than sorry. 

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