Bacterial Colony Morphologies!
Figure created with Biorender.com
Welcome to the first-ever #micromeded! This week’s topic is the bacterial colony morphology. The most important part of clinical microbiology is the colony description. Being able to communicate the appearance of a bacterial colony is vital to communicating with colleagues in the lab. The morphologic description also helps determine if there are more than one species or strain of bacteria present! Here I have designed an infographic to help standardize the language of the microbiology lab. This is one of the first topics covered in the PathElective clinical microbiology module, so if you are interested, check out that course for more info.
Remember: the bacterial colony morphology might change depending on what agar it is on. For instance, Proteus mirabilis is a motile, swarming bacterium, so when grown on blood agar, it can be very challenging to tell if there are other colony morphologies present, but when grown on a more restrictive agar like cysteine lactose electrolyte deficient (CLED) agar can dramatically alter the colony morphology making isolation of other unique colonies easier. Additionally, filamentous fungal colonies (i.e.: non-yeast isolates) will have a slightly different language in the description of their colonies and will include an expanded texture vocabulary and reverse color (the color of the colony from the underside of the agar plate)—we might explore this topic in a later #micromeded post.
1️⃣For all those clinical microbiologists out there, do you put "punctiform" in form or size? I've been in institutions with different opinions on this topic. I'd like to hear what you think!
2️⃣Does anybody know what bacterial species for which “Draughman’s colony” is pathognomonic?
You can also use your knowledge about colony morphologies to design beautiful #AgarArt masterpieces like these:
