![\"Infected](\"http:\/\/farm8.staticflickr.com\/7042\/6839458014_7a509cf345.jpg\")
<\/a><\/p>\nand with a few manipulations, arrive at its precise essence:<\/p>\n
The upper image is, as you’ve probably guessed, a fresh urine specimen from a person with an acute urinary tract infection. The lower image shows what you get when you spin down the urine and take a closer look. The centrifugation collects the heavy sediment, which is enriched for bladder cells that have been shed from the afflicted organ as a sort of bodily defense mechanism – and these tend to be loaded with a cargo of bacteria clinging to their outsides or packed within. Once plated on chromogenic agar, various species of bacteria can take root, grow to macroscopic colonies and be identified by their colors – all based on the agar being spiked with various chemical substrates that interact in different ways with different bacterial metabolism systems. <\/p>\n The plate above shows that the culprits in this patient are largely E. coli<\/em> (brownish colonies), with a smattering of Enterococcus<\/em> (blue). Depending on what’s in the urine, these plates can reveal a rainbow of possible microbes. And by performing dilutions and doing a little back-calculation, you can work out the exact concentration of each species.<\/p>\n None of this is Large Hardron Collider-style stuff; the color tricks may be fancy and newfangled, but the rest of the general procedure is ancient by modern science standards. Still, I think that that sometimes the classic tricks are the most satisfying. Sure, from here we’ll use PCR and sequencing to identify strains from their ribosomal RNA content, and eventually fluorescence in situ hibridization to work out precisely which bugs are getting inside cells, but for me, this initial discovery step will be a lot more magical.<\/p>\n","protected":false},"excerpt":{"rendered":" There are many things I love passionately about science, but one aspect has got to be right up there in the top ten: the transformation of a deep unknown into perfect clarity. I find it amazing that using simple lab … Continue reading ![\"Bacterial](\"http:\/\/farm8.staticflickr.com\/7049\/6839457590_853e53e7cd.jpg\")
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