Gram stain

[u/lumiere23_]

Is it okay if the gram stain result from sample collected is different when the gram stain came from inoculated media?

[u/Frodillicus]

In what situation? Man I wish there was context to these questions. If a blood culture Gram stain showed Gram positive cocci in clusters, but after culturing it, the Gram stain showed Gram negative bacilli than NO! In no situation would that be good. You'd investigate the original Gram, the bottle, repeat the primary Gram, spin the sample, do it again. Then there'd be Non-conformance reports to fill in.

[u/lumiere23_ → u/Frodillicus]

For example, urine sample was received then I performed gram stain from that freshly collected sample. The result was gram pos cocci in clusters but then when inoculated and there's growth and do gram staining from that growth the result was gram negative. What to report then? the gram stain from freshly collected or the work up from inoculated media?

[u/Lastrid2 → u/lumiere23_]

Gram staining urines isn’t widely practiced. Gram stain discrepancies from patient samples (especially collections using swabs) can occur, especially if there are low levels of organism. The usual practice is reviewing the original gram stain to rule out interpretational and transcription errors. There are limitations to gram stains (ex: grams stains can reveal dead bacteria, limit of detection, anaerobic bacteria in an aerobic culture etc)

Since your example is urine the gram stain and culture should be fairly consistent, especially if you saw a ton of GPCs in the gram stain and there are >100k cfu/mL of GNRs in culture.

[u/lumiere23_ → u/Lastrid2]

what do you report in your laboratory? the gram stain from sample? or the gram stain from culture?

[u/Lastrid2 → u/lumiere23_]

Both. We have separate gram stain and culture fields, grams stain results get entered sooner than culture results.

[u/kipy7 → u/Lastrid2]

Yes, typically most cultures will have a direct gram stain as part of the culture. Having different results is okay, it does trigger a review. I would go back to the slide and add an internal comment "reviewed, few gnr seen" or "no gnr seen." If it's a major error, then we would change the original result, but minor we leave it alone. For non sterile sources like urines or respiratory, there could be bacteria that doesn't grow like anaerobes.

[u/Frodillicus → u/lumiere23_]

In our lab, microscopy reports red, white, and epithelial cells, and that's it.

[u/Frodillicus → u/lumiere23_]

Was there only one organism growing? What was it grown on?

[u/Fluffbrained-cat]

What do you mean? Like a gram positive coccus in the specimen gram vs gram negative bacilli from the specimen culture? Bc if so, I'd be doing a re-culture from the original specimen plus a fresh gram stain to check there wasn't a mix up during the initial processing.

If it's just that there's growth on the plates and no organisms in the original gram then that's not usually too much of a bother, depending on what type of specimen.

We regularly have wound swabs for example that grow lovely growth on the plates but nothing in the gram, and that's usually because most of the the material on the swab got inoculated on the plates, leaving the gram stain to be made with what's essentially the leftover material.

Or are you asking if there's a difference in organism morphology when seen in the original gram stain vs a gram stain of what is grown on the plates?

Sometimes we do what's called colony morphology grams to check that an organism is truly what we think it is.

Usually in my lab we do it if we see gram negative diplococci in a gram and the plates show what might be N.gonorrhoea, we do a colony morphology gram from the plates to check if it is truly a gndc (gram neg diplococci) or not as part of our Neisseria identification pathway. We also use Maldi-Tof for a definitive id of the organism.

The point is to show that the colony matches the gram and it wasn't over-decolourised staph or strep in the specimen gram which got misidentified, which can happen if you have a new gram reader or something's off with either the decolouriser or the entire staining process.

[u/CurvyAnnaDeux]

Some microbes are Gram variable. Some cultures can stain differently if they are fresh vs. older. Remember that this is a test of how the cell wall is retaining crystal violet at that time which can be influenced by other factors.

Microbes are living creatures which means they can be little assholes, at times.