When I tell people my lab make nasty bacteria glow in the dark, they usually look at me a bit funny. They look at me even funnier when I tell them it helps us see where the bacteria are. Seriously. Everyone must have done that experiment where you put your hand over the top of a torch, and you can see the light shining through. Well, we replace the torch with glowing bacteria, and the hand with a mouse and our eyes with a sensitive camera that can pick up very low levels of light. And sometimes the bacteria turn up somewhere quite unexpected….
The image above was taken by my PhD student Faz, during his studies of a bacterium called Streptococcus pyogenes. During his PhD, Faz made glowing S. pyogenes and developed a mouse model for nasal/throat carriage to test potential vaccines. Hence the glowing nose. His work has just been published in the open access journal PLOS One (1) and while you won’t find any speculation of the reason behind the glowing genitals in our paper, he has done a little musing here.
Pretty much everyone will have had an S. pyogenes infection at some stage in their life – it causes tonsillitis – and many people will be carrying the bacterium in their throats. S. pyogenes can also cause a life-threatening illness called necrotizing fasciitis, literally the flesh-eating disease, where the bacterium produces an enzyme that digests away the tissue and can require amputation of the infected limb. In fact, S. pyogenes is an incredibly versatile pathogen that can also cause skin diseases, scarlet fever and rheumatic heart disease. it is also the only bacterium that has been documented to spread through farting (2,3)!
The mouse in the picture is female, and her glowing vagina* is a great demonstration of just how flexible S. pyogenes is as a pathogen. It is also a powerful demonstration of how diseases can take unexpected turns, and glowing bacteria can show us what happens when they do.
*The lovely people responsible for the Ig Nobel’s quite liked this as great example of science that makes you laugh and then think.
1. Alam FM, Bateman C, Turner CE, Wiles S, Sriskandan S (2013) Non-Invasive Monitoring of Streptococcus pyogenes Vaccine Efficacy Using Biophotonic Imaging. PLoS ONE 8(11): e82123. doi:10.1371/journal.pone.0082123
2. Schaffner W, Lefkowitz LB Jr, Goodman JS, & Koenig MG (1969). Hospital outbreak of infections with group a streptococci traced to an asymptomatic anal carrier. The New England journal of medicine, 280 (22), 1224-5 PMID: 4889553
3. McKee WM, Di Caprio JM, Roberts CE Jr, & Sherris JC (1966). Anal carriage as the probable source of a streptococcal epidemic. Lancet, 2 (7471), 1007-9 PMID: 4162660