Antibiotics and blood cultures

[Iseeyou_RN, RN]

I read in another post recently that it's not necessary to draw blood cultures before antibiotics are given; that this is actually a "sacred cow". I'd be really interested to learn if this is true and where I could find resources for this info as I haven't read this anywhere.

Thanks

[TemperStripe]

I hadn't heard this and it doesn't make a lot of sense to me...if you have a source, I'd be interested in reading it. My only thought is that antibiotics take long enough to kill bugs that you could administer the first abx and THEN draw cultures without too much change in what might grow out? Let me know what you find out.

[detroitdano]

It's our unspoken policy too, no one will fire you for it but usually we grab cultures before starting antibiotics.

From what you all probably already understand, it's because you want to identify the organism before you kill it off with the abx supposedly, but here's another that MIGHT be the reason we do it.

If you give antibiotics you lyse a lot of intracellular debris from the bacteria into the blood, which may mess up cultures somehow. It's the reason sometimes steroids are given before antibiotics are started. The intracellular products kickstart your white cells to attack. I'm sure it could be worded a little more pretty, but I do recall learning that at one point.

[haji]

the books i've read all say that cultures should be done before starting abx therapy, but also that abx shouldn't be delayed. the longer you wait to start antibiotics in sepsis the more mortality increases. but if you draw cultures first you can then pick the right drug for the bug.

i thought the point of using steroids in infection/sepsis was to treat adrenal insufficiency, not to treat the infection. steroids suppress the immune system.

[detroitdano]

the books i've read all say that cultures should be done before starting abx therapy, but also that abx shouldn't be delayed. the longer you wait to start antibiotics in sepsis the more mortality increases. but if you draw cultures first you can then pick the right drug for the bug.

i thought the point of using steroids in infection/sepsis was to treat adrenal insufficiency, not to treat the infection. steroids suppress the immune system.

True, but both have their own rationale. IIRC you give steroids before antibiotics in people with neurological issues so you don't cause further swelling and bump up ICP due to the inflammatory mediators that will be present in your blood once the bacteria lyse. It's not just for those with a septic picture. I may be providing the wrong reason here, so if someone can toss out some cited data, I'd appreciate it to remind myself where I've heard this before!

Steroids are given in sepsis as you said, there's no denying that. It's proven to be effective even with an unimpared adrenal response, but they'll especially give it if the patient fails a cosyntropin test.