Giant Cocci

         One night, one of my colleagues approached me about something he hadn't seen before in the microscope. He was working on blood cultures and doing the preliminary workups.

         He thought they could be yeast at first look, but further inspection suggested otherwise. They were much bigger than the usual gram-positive bacteria we come across daily. These guys were at least 2-3x the size! (We are talking about things 1.8 to 3.0 microns.) And no, yeasts don't look like that in the gram stain.

         The rapid molecular method didn't yield clear identification, but the instrument leaned towards Sarcina species. I had never seen this organism in a septic patient before, so this became a learning experience.

         A quick internet search told us that Sarcina species are anaerobic organisms. That made sense since it was the anaerobic bottle that became positive. They are rare pathogens in humans but seem to be problematic in livestock. One of the unique descriptions for this organism was "anaerobic giant gram-positive cocci". Surprisingly, one of the sources that documented human cases was sepsis. I would say we were on the right track.

         When the culture grows, we could do more tests to identify and perform susceptibilities on the organism. For the moment, I was content with the information I learned with my coworker.

For further reading:

Other Sarcina cases
Wiki info - apparently, Sarcina species are related to Micrococcus species.

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