Antibiotic resistance

Re: Antibiotic resistance

bob lehner — Fri, 14 Jan 2011 14:14:57 GMT

[quote user="robloxley"]You mean you don't need a 14 day duration injection of a 3rd generation cephalosporin for a CBA?[/quote]

Well I have encountered on my travels one gent who was using Marbocyl as his routine post op ab - possibly to compensate for less than sterile surgery.,,,,?

Re: Antibiotic resistance

Rob Loxley — Fri, 14 Jan 2011 13:39:25 GMT

[quote user="bob lehner"]

In my early days all simple things like your routine cba were treated with straight forward penicillin - and I don't recall many problems with lack of efficacy.

Drug firms pushing their newer products so vigorously has surely also promoted their use inappropriately.

[/quote]

You mean you don't need a 14 day duration injection of a 3rd generation cephalosporin for a CBA?

Re: Antibiotic resistance

bob lehner — Fri, 14 Jan 2011 10:40:10 GMT

[quote user="robloxley"] We also have pots of good old oxytet, ampicillin and amoxicillin on the shelf. In fact I sometimes miss the small size amfipen that were discontinued a while back.[/quote]

Yes - it's interesting how things change . In my early days all simple things like your routine cba were treated with straight forward penicillin - and I don't recall many problems with lack of efficacy. Pen/strep, TMP, oxytet and ampicillin were reserved for anything a bit more tricky.

Then amoxycillin, amoxclav, cepo, enroflox etc. came along and were used more and more for routine things. I think it is fair to say that nowadays many vets use amoxyclav as their first line treatment for things where something more basic would be just as effective. Drug firms pushing their newer products so vigorously has surely also promoted their use inappropriately.

Re: Antibiotic resistance

Mark Hedberg — Thu, 13 Jan 2011 22:06:23 GMT

The other nice thing about TMP is that people who are allergic to penicillin (runs in my family) can take it and not worry. I have had dry eye the last few months...has started me wondering.

Re: Antibiotic resistance

Rob Loxley — Thu, 13 Jan 2011 19:20:28 GMT

[quote user="patrick murphy"]I would love to reconsideer as they really are the best bargain bang for buck ab's that are aqbout.[/quote]

Yup, they are phenomenally and good cheap broad spectrum antibiotics. I'm informed they get lots and lots of use in charity practices, but there's lots of scope for use generally but just being careful.
Have to say I don't routinely do STTs unless using a long course (and that's usually on the basis of culture/sensitivity) or KCS prone breed. We also have pots of good old oxytet, ampicillin and amoxicillin on the shelf. In fact I sometimes miss the small size amfipen that were discontinued a while back.

Re: Antibiotic resistance

patrick murphy — Wed, 12 Jan 2011 13:52:04 GMT

it is weird how TMS had suddenly swung aaround. I can remember on another post and also a gp going nuts about it, and now it is being prescribed on the NHS. I would love to reconsideer as they really are the best bargain bang for buck ab's that are aqbout.

Re: Antibiotic resistance

Mark Holmes — Wed, 12 Jan 2011 10:51:13 GMT

I use it for short ? 5 day courses. Kennel cough for example. But skins where 2-4 weeks may be needed. No not unless costs are a great concern and not in pre disposed breeds.

Re: Antibiotic resistance

Rob Loxley — Tue, 11 Jan 2011 23:47:37 GMT

[quote user="Mark Holmes"]I have had a few dogs develop permanent dry eye following prolonged TMPS which is why I avoid it in skin cases and any case which is going to result in a long course. Anybody else run into this? [/quote]

And a few of the other (long list) of sulphonamide side effects. That's not to say I don't use it but with a bit of caution.

Re: Antibiotic resistance

Mark Holmes — Tue, 11 Jan 2011 23:28:40 GMT

I have had a few dogs develop permanent dry eye following prolonged TMPS which is why I avoid it in skin cases and any case which is going to result in a long course. Anybody else run into this? The last was a golden retriever so not one that you would expect dry eye to develop in spontaneously.

Re: Antibiotic resistance

Julian Earl — Tue, 11 Jan 2011 21:00:48 GMT

[quote user="Mark Hedberg"]My fear with minimum doses is that you run the risk of insufficient effect. Will the client care about your efforts to apply selective pressure on bacteria. They want fluffy to get better immediately. If you give a lower dose with no effect, then give a higher dose, doesn't that run the risk of making resistance worse?

(assume for example that the client can't or won't afford sensitivity testing or multiple vet visits. )

[/quote]

Although I raised the question of just how high concentrations ought to be if we are trying to avoid resistance, in truth my main concern is the duration of treatment. The concentration aspect is impossible to judge accurately in a practical situation, but we can easily choose when to stop a course of antibiotics. Consequently the real practical question is, should we be always be continuing the course for the extra two days or two weeks after symptoms have cleared? If two days, why not one nd a half, or one (days or weeks)?

Re: Antibiotic resistance

Julian Earl — Tue, 11 Jan 2011 20:52:45 GMT

[quote user="Michael Woodhouse"]

[quote user="David Beattie"]I generally try to use TMPS (30mg/kg q12hrs) as first-choice for pyoderma, and only cephalexin if required due to TMPS resistance. [/quote]

Datasheet is 30mg/kg/24 hours.

[/quote]

Funnily enough I "re-discovered" (=remembered) double-dose TMPS for skins recently and was reminded quite dramarically how effective it can be. A lot cheaper than most cephalosporins, and all pot.amoxes as well.

Re: Antibiotic resistance

Michael Woodhouse — Tue, 11 Jan 2011 13:37:01 GMT

[quote user="Mark Hedberg"](assume for example that the client can't or won't afford sensitivity testing or multiple vet visits. )[/quote]

Even if money is not an issue IMO it is very rare to have an infection that can wait 3 or 4 or 5 days to get a sensitivity report back before starting treatment.They get an antibiotic that is licensed and you have experience/evidence of previous efficacy.

We may know what MAC is required in vivo but in the actual patient issues with penetration/excretion/pH can all affect the local tissue concentration so we might not have MAC where we have the bug. I'm not sure MAC's are much more use than a line of 'S' and 'R'.

Re: Antibiotic resistance

Mark Hedberg — Tue, 11 Jan 2011 09:42:57 GMT

My fear with minimum doses is that you run the risk of insufficient effect. Will the client care about your efforts to apply selective pressure on bacteria. They want fluffy to get better immediately. If you give a lower dose with no effect, then give a higher dose, doesn't that run the risk of making resistance worse?

(assume for example that the client can't or won't afford sensitivity testing or multiple vet visits. )

Re: Antibiotic resistance

Alex Allen — Tue, 11 Jan 2011 09:24:00 GMT

This is a hugely important subject that a significant proportion of the profession seem to be hiding away from. A few important issues have been raised here such as the use of 3rd and 4th Generation Cephalosporins preferentially over traditional antibiotics based on convenience or non-scientific decisions. A common misconception is that these higher generation cephalosporins are more efficacious against the infections when compared to their 1st generation relatives. In reality the mechanism a 4th gen kills a Staph intermedius (or pseudointermedius for the purists) is exactly the same as the 1st gens like Cephalexin! The higher generation nomenclature relates to the chronological development of the molecules and typically these more recent molecules will have different spectrums of activity - usually more gram negative activity with 3rd and 4th gens. Of course on a human health front the gram negs are the area of concern so this worries the medical advisors when they see them being used in the food animals. This doesn;t mean the small animal world escapes scrutiny as molecules like Fusidic acid may come under the microscope given its use in treating troublesome Staphylococcal infections

As David mentioned the Time and Concentration functions are critical to resistance but so are several other factors such as population dynamics. i.e. hospital acquired infections are, in part, due to a higher density of a certain organisms in an environment of intense antibiotic usage and immunosuppression. Care must be taken when comparing antibiotic treatments for a herd versus an individual pet dog.

An interesting fact is that the resistance profile of some very old antibiotics are relatively unchanged over the decades of their use - cephalexin, gentamicin naming just two. It is no coincidence that these are both Concentration dependent antibiotics and their pharmokinetics/dynamics favours efficacy over resistance. Be careful comparing to parasites and the refugia principle as some concepts are not transferable to bacteria infections.

Topical versus Systemic = this is again a very active area of discussion and debate with several molecules being inappropriately used every day. Tissue concentrations, MIC points and susceptible organisms must be considered. For example using a standard dose fluoroquinolone in a chronic otitis externa case with a Susceptible organism may actually induce resistance! The reason is simple - the concentration of the drug may be as expected in normal tissues but at the level of the thickened ear canal the concentration is close to the MIC point => selection of a subpopulation of resistant bacteria. Topically the same fluoroquin maybe perfect as the concentration of the molecule is far in excess of the MIC point. Also the environment of the infection may influence antibiotic function - classical scenario is milk - pH - what may work in a cow may not in a bitch. Some antibiotics may become second line when used systemically for various reasons - usually toxicity and Gentamicin is a good example. Perfect topically given its safety margin, broad spectrum, concentration dependent action but given systemically and the patient could suffer nephrotoxicity before the infection clears!

How many vets prescribe an ear treatment WITH an ear cleaner? ALL the ear treatments licensed have a proviso for treatments to be applied to cleaned ears. The reason - organic matter and bacterial biofilms inhibit / impede antibiotic function. Also with ears the infections are being complicated by other processes - inflammation being the most common and significant. Controlling / diagnosing the underlying problems may make the antibiotic choice and protocol more appropriate particularly if multimodal therapy is used.

I've waffled for long enough but this is a topic that is unappreciated in general practice and it will come back to bite us on the proverbial...

Re: Antibiotic resistance

Evelyn Barbour-Hill — Tue, 11 Jan 2011 00:42:49 GMT

I confess I never understood the "big doses for long periods, or you'll be inducing resistance" dogma. I've always thought "minimum effective dose for as short a time as possible" would exert least selection pressure for resistance. It's not an original thought: people pop up from time to time and say the same.

Re: Antibiotic resistance

Anonymous — Mon, 10 Jan 2011 23:20:04 GMT

[quote user="Michael Woodhouse"]Datasheet is 30mg/kg/24 hours. [/quote]

Yet there is some logic to the higher dose suggested by many dermatologists to reach effective therapeutic levels in the skin or middle ear.

I'll plead ignorance if the datasheet police come after me and quote:

"Dogs: One tablet per 32 kg bodyweight twice daily or one tablet per 16 kg bodyweight once daily." from the online NOAH compendium Tribrissen Tablets. Oral tablets for dogs: Dosage and administration advice. I just checked this and it does still say that - honest!

http://www.noahcompendium.co.uk/Intervet_Schering-Plough/Tribrissen_Tablets___Oral_tablets_for_dogs/-34784.html

I have of course committed this advice to memory and it would not be expected for me to check online for updates to such an old drug license regularly

Re: Antibiotic resistance

Michael Woodhouse — Mon, 10 Jan 2011 22:58:46 GMT

[quote user="David Beattie"]I generally try to use TMPS (30mg/kg q12hrs) as first-choice for pyoderma, and only cephalexin if required due to TMPS resistance. [/quote]

Datasheet is 30mg/kg/24 hours.

Re: Antibiotic resistance

Michael Woodhouse — Mon, 10 Jan 2011 22:56:00 GMT

[quote user="David Beattie"]perhaps reduce the mark-up on the vaccines and increase the mark-up on the antbiotics, then hey-presto - vaccinating is not only the recommendation, but also the cost-effective choice![/quote]

We certainly mark up vaccines less than antibiotics. From a business point of view it might be better not to reduce their cases of pneumonia and mastitis with the nice mark up on the antibiotics!

[tongue in cheek, before I get slated].

Re: Antibiotic resistance

Anonymous — Mon, 10 Jan 2011 22:44:55 GMT

[quote user="Vikki Halliday"]

Of course, but the general issue of resistance is tending towards cephalosporins and fluroquinolones, so moving away from them to sulphonamides is possibly not a bad thing.

Why would we reach for cephalosporins in the first instance anyway? Because dermatologists got results with them and then advised us to do the same?

I for one will seriously reconsider my choice of antibiotic with more care in future instead of reaching for the Ceporex at the first sign of pyodermas.

[/quote]

Hear, hear, again, Vikki! I generally try to use TMPS (30mg/kg q12hrs) as first-choice for pyoderma, and only cephalexin if required due to TMPS resistance. Again I use topical treatment (e.g. 'Etiderm shampoo', fusidic acid) for pyoderma where appropriate and have moved away from automatically dispensing systemic antibiotics which often reach poor concs in the skin automatically on seeing epidermal collarettes, especially if lesions are restricted to certain areas. Also try to address cause of pyoderma, to the extent of preferring to use long term glucocorticoids than repeated 2 month courses of cephalexin throughout a dog's life - I find it hard to get specialist recommendations from a dermatologist on what is and isn't appropriate antibiotic use as I am of the belief that a lot of them don't seem to share my concerns about antibiotic resistance?

Re: Antibiotic resistance

Anonymous — Mon, 10 Jan 2011 22:31:37 GMT

[quote user="Vikki Halliday"]

[quote user="Michael Woodhouse"]As it was the farmer's prefer giving the Cephalexin over the Ceftiofur as it could be given into the muscle rather than under the skin, and it was cheaper![/quote]

Yep but it's you that is supposed to be doing the prescribing, not the farmer on the basis of cost!

[/quote]

Though in this case, like in many, it's the cheaper antibiotic that is less of a concern if resistance is induced. A harder one I felt was when farmers felt it cheaper to use antibiotics for pneumonia rather than vaccines (whether it was cheaper in terms of decreased growth rates from subclinical disease etc is obviously debatable, but farmers aren't stupid and are aware that all these disease cost calculators cannot possibly be correct or their financial situation would be even worse than the top-performers than it is). I would argue here that as a professional, the vet has a responsibility to 'prce for good practice', i.e. perhaps reduce the mark-up on the vaccines and increase the mark-up on the antbiotics, then hey-presto - vaccinating is not only the recommendation, but also the cost-effective choice!

Re: Antibiotic resistance

Anonymous — Mon, 10 Jan 2011 22:18:47 GMT

Fair answer, Michael. As it is, in my experience (in a different microbial climate perhaps), ceporex seemed to work fine for metritis (I tended to give a 5 day course from memory) and could never really see any point to pessaries (very rarely did a farmer insist, but they ddn't get cephalosporins shoved in there even if they did insist). I agree with you about the limits to the "in my experience", and in this case I'd say limits to the actual trial evidence-base also as ceftiofur clearly comes out on top as Pfizer have paid for and done published studies on it (though oddly not a RCT comparing efficacy with a correct dose of cefalexin!) I take your point re the depo injections (though I'm not totally convinced yet), but only wish that the drug company didn't insist on using 3rd gen cephalosporins in these useful phamacological products).

PS - I think a RCT of cephalexin vs ceftofur for metritis in the UK would be an excellent study :-)

Re: Antibiotic resistance

Vikki Halliday LLB — Mon, 10 Jan 2011 22:15:19 GMT

[quote user="Michael Woodhouse"]You never given a dog with bad skin a long course of Sulphonamide as the owner can't afford the Cephalexin? [/quote]

Of course, but the general issue of resistance is tending towards cephalosporins and fluroquinolones, so moving away from them to sulphonamides is possibly not a bad thing.

Why would we reach for cephalosporins in the first instance anyway? Because dermatologists got results with them and then advised us to do the same?

I for one will seriously reconsider my choice of antibiotic with more care in future instead of reaching for the Ceporex at the first sign of pyodermas.

Re: Antibiotic resistance

Michael Woodhouse — Mon, 10 Jan 2011 22:09:13 GMT

[quote user="Vikki Halliday"]Yep but it's you that is supposed to be doing the prescribing, not the farmer on the basis of cost![/quote]

Yes Vikki, but as production animals decisions have to be made daily on cost of treatment vs slaughter. I'm not prescribing inappropriate products based on cost, but how much it is and the ease of administration aids compliance with my instructions!

You never given a dog with bad skin a long course of Sulphonamide as the owner can't afford the Cephalexin? I have. I will continue to do so. You have to do the best you can with the budget you have got.

Re: Antibiotic resistance

Carlos Michelsen — Mon, 10 Jan 2011 22:07:06 GMT

Interestingly, in a recent Vetspanel survey, half of veterinary surgeons considered they used antibiotics more than they should considering resistance, the other half didn't.

Re: Antibiotic resistance

Vikki Halliday LLB — Mon, 10 Jan 2011 22:03:53 GMT

[quote user="Michael Woodhouse"]As it was the farmer's prefer giving the Cephalexin over the Ceftiofur as it could be given into the muscle rather than under the skin, and it was cheaper![/quote]

Yep but it's you that is supposed to be doing the prescribing, not the farmer on the basis of cost!