@MattDMo Yes, the overall term is that. I wondered how to tranlate Russian "wash-off": "A wash-off from Mr. Smith's forearm contained 300 CFU of gram-positive cocci, against the nominal value of 5 CFU". Probably it's "swab sample" or something like that.

They use "tampons" (cotton swabs) to inspect personnel working in clean rooms.

I just stared at this "wash off" but when googled and it turns out it's just a swab sample.

What is the traditional manner of abbreviating "gram-negative rods"? Can I write "g- rods"?

@arboviral Hmm. OK, you may well be right actually. Perhaps prey go for visual while predators aim for silence.

I voted to reopen. You really should post on meta about this if you want to get more eyeballs on it though.

@CowperKettle I would stick with "Gram-negative rods" (notice the capitalization). In industry microbiology labs they're often referred to as "GNRs", just like Gram-positive cocci (skin bacteria) are abbreviated as "GPCs", but unless you've specifically defined your abbreviation previously, don't assume you can abbreviate something.