All of the comments are by armchair biologists about how the scientists are wrong and all bacteria strains will become resistant to it in 2 days.
But anyways, if it is an issue, why can't we just require antibiotics be taken intravenously? The vast majority of bacteria exposed to antibiotics are in your digestive system and that is where resistance develops. Or at least that's how I understand it.
IV antibiotics generally mean hospital, which generally means severe life-threatening infection.
Outpatient IV antibiotics are done but it's complicated and carry further risk of infection through having a line in situ for long periods of time.
IV antibiotics do have an effect on gut bacteria as well, it's not as simple as just not giving oral;
additionally (and, perhaps the crux of the issue) is that gut bacteria exposure to antibiotics is not how resistance develops; and certainly aren't the main problem.
It is the more common infective agents that cause the problems - Gram positive organisms (Strep Viridians, Staph Aureus etc) that usually enter from cuts or abscesses and, in the immunocompromised, cause significant disability.
>IV antibiotics do have an effect on gut bacteria as well, it's not as simple as just not giving oral;
How so? And more importantly how much antibiotics make it to the gut, vs if you take it orally? I would guess it would be a lot less.
>It is the more common infective agents that cause the problems
I know that, but as I understand it the resistance first evolves in gut bacteria, then spreads through horizontal gene transfer. Wikipedia cites this as the main cause of antibiotic resistance: https://en.wikipedia.org/wiki/Horizontal_gene_transfer
> How so? And more importantly how much antibiotics make it to the gut, vs if you take it orally? I would guess it would be a lot less.
I have no idea what figure or percentage it would be, but for most common antibiotics which end up distributed in total body water, there will be a component that leaks into the gut through capillary action; if it is metabolised in the liver then a proportion of it will end up in bile (if fat soluble) and then enter the gut that way; either itself or a metabolite of it - it would be impossible for me to quantify and likely depends on many many factors such as molecular weight, structure and a host of other features.
Patients on IV antibiotics develop diarrhoea from IV antibiotics at a similar rate (from what I have experienced) to those on orals. hence it undoubtedly kills bacteria in a similar fashion.
And we use IV antibiotics to kill bad infections of the gut. So whatever the mechanism, if I have elucidated it or simply done some hand-waving, it clearly affects it significantly.
The only instance of antibiotic use that touches on what I feel you are pushing for is the use of oral vancomycin (It is almost always IV) for severe bacterial infections of the gut - we use it oral because it is not absorbed systemically (as opposed to other specifically oral antibiotics) so doesn't cause systemic effects.
> then spreads through horizontal gene transfer.
Sure. But if you look at how they tested this particular antibiotic for the ability to develop resistance, they exposed TB and Staph to sub-theraputic doses for 27 days, or (for Staph) or 810generations (assuming a rough rate of division somewhere around 40 min to 1 hr in ideal conditions). An epic number of cell divisions if you work it out (and I can't).
The commonly accepted knowledge, as far as I understand it and as far as I have been taught it, whether or not bowel bacteria have a significant role to play or not, is that exposure of antibiotics to sub-lethal doses for long periods of time promote the survival of strains that have a competitive advantage against the agent in use, which over time allows the strain to survive in otherwise-lethal doses, and that gene becomes incorporated into a plasmid and then ends up spreading to every other organism capable of horizontal gene transfer.
Anyway, I am at home and not going to see the next MD, PhD in Infectious Diseases until tomorrow but when I do I will ask him and reply here. So, check back in 24 hours if you're interested
On the off-chance that you read this I apologise for not delivering, I wasn't able to speak to ID but will on Monday so if this thread is locked by then then shoot me an email
Don't assume everyone on here is an "armchair biologist".
There are several problems with IV antibiotics, some of which have been outlined in other comments:
1. It involves an IV. This means a hospital - that's both expensive for all involved, and the presence of an IV is in and of itself a risk for bacterial infection. Not all antibiotics kill all bacteria.
2. "The vast majority" = / = the ones experiencing resistance that are of clinical concern. C. difficile lives in your gut. MRSA on the other hand can live on your skin, and colonize your nasal passages. Both, additionally, cheerfully live on surfaces for quite some time (really quite some time for C. difficile).
3. IV antibiotics can reach your gut - some are excreted into the intestines. Metronidazole is, vancomycin isn't for example. And beyond that, much of the concern is with active infections, which are very likely not in your gut for many diseases, in contrast to just the background of your intestinal flora.
4. You're asserting that antibiotics reaching your gut from an IV would arrive in low doses. That's a good thing for promoting the development of resistance, not a bad thing, from the bacteria's perspective.
But anyways, if it is an issue, why can't we just require antibiotics be taken intravenously? The vast majority of bacteria exposed to antibiotics are in your digestive system and that is where resistance develops. Or at least that's how I understand it.