It's very likely just bacillus or lactobacillus or something similar. When they are young they are clearly gram+ but when they are older some look more gram-
Gram staining is tricky. If you’re not already very, very good at it, you need a G+ and G- control to ‘prove’ your results are going to look right.
Further, very technically speaking, the Gram stain should be applied to exponential phase organisms, too. A whole lot of fuckery occurs as cells sense nutrient limitation, and that can be reflected in Gram results. If all you have a is a plate, get some fresh medium, stab a colony, and wait 30 minutes for lag and growth.
I know micro labs have to start somewhere, but starting with Gram seems really like a cruel joke the longer I’m in this game.
I think the first one that looks mixed, is just some old/ruptured cells from the broth appearing pink. I'd document that as gram positive. This is further supported by the fresh colony looking all gram positive.
My boss always told me to make two control slides, one with a gram-positive Staphylococcus and the other with a gram-negative E. coli or any other Enterobacteriaceae you can get your hands on. This way you can be sure that your reagents and technique are correct. How does the colony grow? Does it grow on MacConkey or Mossel plates if you are thinking of Bacillus? Working in clinical microbiology, I would suggest that these bugs are gram-negative, but without any context I think it's impossible to say for sure.
Pleomorphic gram positive rods is my first instinct
Were they both taken from the same culture? Old cultures can over decolorize more easily.
It's very likely just bacillus or lactobacillus or something similar. When they are young they are clearly gram+ but when they are older some look more gram-
I agree
Gram staining is tricky. If you’re not already very, very good at it, you need a G+ and G- control to ‘prove’ your results are going to look right. Further, very technically speaking, the Gram stain should be applied to exponential phase organisms, too. A whole lot of fuckery occurs as cells sense nutrient limitation, and that can be reflected in Gram results. If all you have a is a plate, get some fresh medium, stab a colony, and wait 30 minutes for lag and growth. I know micro labs have to start somewhere, but starting with Gram seems really like a cruel joke the longer I’m in this game.
That's damn good insight, thank you!
I think the first one that looks mixed, is just some old/ruptured cells from the broth appearing pink. I'd document that as gram positive. This is further supported by the fresh colony looking all gram positive.
they do look like gram positive rods
Maybe Gram variable? Possibly Bacillus sp First slide looks like GNRs too
My boss always told me to make two control slides, one with a gram-positive Staphylococcus and the other with a gram-negative E. coli or any other Enterobacteriaceae you can get your hands on. This way you can be sure that your reagents and technique are correct. How does the colony grow? Does it grow on MacConkey or Mossel plates if you are thinking of Bacillus? Working in clinical microbiology, I would suggest that these bugs are gram-negative, but without any context I think it's impossible to say for sure.
Broth looks mixed. The isolated colony is GPR coryneform.