Would anyone be willing to explain the D test (aka Double Disc Diffusion Test) with regard to Clindamycin and Erythromycin?
"D Test" - Clindamycin, Erythromycin
- Thread starter Strontium
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Funny, I was literally just listening to this on lecture. I think the gist is that erythromycin can induce clindamycin resistance. So if you grow the bacteria on a plate with an erythro next to a clinda pill, the bacteria will be killed around the clinda except in the region where it gets close to erthro. The result is that you get a D-shaped area of no bacteria around the clinda.
Anyone care to comment? I just heard this in lecture so I might be misunderstanding here.
Anyone care to comment? I just heard this in lecture so I might be misunderstanding here.
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I don't know, or care, about the lab aspects of this test, but the functional significance of this for clinicians is that if a bug, staph aureus, is resistant to macrolides, you should assume that it has inducible resistance to clindamycin as well, despite the fact that it is marked as 'susceptible' by the lab.
This is especially relavent if you're at a site, usually peds, where they, often inappropriately IMHO, use clindamycin extensively for its 'coverage' of mrsa.
This is especially relavent if you're at a site, usually peds, where they, often inappropriately IMHO, use clindamycin extensively for its 'coverage' of mrsa.
Im not a medical student yet, but I did these tests working as a microbiology technologist 😀
Its looking for inducible clindamycin resistance. You put the discs next to each other, measure the zone of inhibition. There are standards for this, but it gives the ability to correctly report out clinda. as an antibiotic of choice during a culture and sensitivity.
Its looking for inducible clindamycin resistance. You put the discs next to each other, measure the zone of inhibition. There are standards for this, but it gives the ability to correctly report out clinda. as an antibiotic of choice during a culture and sensitivity.
