Multiresistant pseudomonas cultured from bulla

Re: Multiresistant pseudomonas cultured from bulla

Gerry Henry — Sun, 05 Jan 2014 12:41:06 GMT

Thorough prep with iodine based scrub, meticulous surgery, meticulous stripping and flushing of LB, copious flushing pre sutury, should be fine; all my problems are associated with PEAs rather than TECAs which I now prefer.

Re: Multiresistant pseudomonas cultured from bulla

John Flynn — Sun, 05 Jan 2014 09:37:58 GMT

[quote user="Tim Charlesworth"]I wouldn't worry too much about the swab result at this stage unless you took the swab after flushing? If it was a pre flush swab then you've probably already flushed/cut away the problem.[/quote]

You've raised an interesting point (to me!)

When is the best time to swab for culture in a case of TECA-LBO?

I can see 4 possible options:

1) No cultures

2) Pre-op culture

3) Intra-op culture of bulla prior to debridement/flushing

4) Intra-op culture of bulla after debridement/flushing

Obviously, you can do as many cultures as you like, so could do (3) & (4) together (like folk used to do for open fractures). But if doing just one culture, then I can see pros and cons but would probably opt for (3)? My logic would be that the point of my culture is to see what the bugs in the middle ear that will have contaminated the surgical site were, rather than some sort of test of the adequacy of the debridement/flushing, and if do option (4) then there is presumably a reasonable chance of a negative culture in which case there is nothing to guide any post-op antibiosis?

[quote user="Tim Charlesworth"]I've had quite a few TECA's that have yielded pre flush cultures that aren't sensitive to any ab's that we can give and I tend to get them as clean as I can preop (including flushing++ whilst in prep) and then using a sensible antibiotic postop (e.g. if pseudomonas Aeuriginosa then I'd use a double dose flouroquinolone as resistance tends to be concentration dependent).[/quote]

Resistance is indeed concentration-dependent (though things might be a bit more complicated than a simple dichotomous model of mode of action would suggest: The Veterinary Journal, Volume 198, Issue 1, October 2013, Pages 15-18), but that doesn't mean that it's at all sensible to use a FQ if the pre-op culture indicated that it was resistant?

"For bacteria with an minimal inhibitory concentration of 0.12-0.15 or less, 0.19-0.24, 0.31-0.39 and 0.51-0.64 µg mL^-1, enrofloxacin should be dosed at 5, 10, 15 and 20 mg kg^-1, respectively. Treatment with enrofloxacin would not be recommended for a bacterial organism intermediate or resistant in susceptibility to enrofloxacin since appropriate levels of enrofloxacin would not be attained....

"However, P. aeruginosa ear infections, where MICs of enroﬂoxacin tend to be higher (typically 0.5 μg mL–1),31 should be treated with the high end of the enroﬂoxacin dose range (20 mg kg–1). These data are more difﬁcult to use when the culture results are obtained by disk diffusion, when it is assumed that any susceptible organism could have an MIC as high as 0.5 μg mL–1 and would need a dose of 20 mg kg–1. Furthermore, it would be inadvisable to treat an intermediate or resistant (on the basis of either disc diffusion or broth microdilution (MICs)) organism with enroﬂoxacin, since appropriate tissue levels could not be obtained."

(Veterinary Dermatology 2009 Vol. 20 No. 1 pp. 51-59)

Additionally (to the original poster), I personally think that culture with MIC should be used in such cases and isn't typically more expensive than labs offering disc diffusion tests.

Re: Multiresistant pseudomonas cultured from bulla

Beats — Sat, 04 Jan 2014 18:23:15 GMT

Thanks everyone for advice and suggestions.

In the end I continued the tobramycin that had been started that day for 10 days in total at 3mg/kg q24hrs SC.

Don't know if that made any sense or not, but figured having started on it for a day was probably as well to make some sort of a course out of it at that stage.

Has made me think about what others do re antibiotics in TECA/LBO cases. I guess there are probably as many opinions out there as surgeons!

There is, however, very little published re complication rates period, let alone with respect to use of antibiotics, so I guess it's just by discussing the experience of others that I can learn more.

I was interested to read the approach of the author's establishment in the most recent review of complications:

"All patients were discharged from the hospital with instructions to administer oral antibiotics and an oral analgesic/anti-inflammatory drug. Amoxicillin trihydrate/clavulanate potassium was prescribed following 48 surgeries, cephalexin was prescribed following 45 surgeries, and enrofloxacin was prescribed following 28 surgeries. Other antibiotics used postoperatively were marbofloxacin, orbifloxacin, metronidazole, chloramphenicol, trimethoprim/sulfonamide, cefpodoxime, and cefadroxil. Antibiotics were prescribed for a minimum of 1 wk postoperatively, pending the intraoperative bacterial culture results. If the bacterial culture was positive and the bacteria were sensitive to the empiric antibiotic choice, an additional 2–3 wk of that antibiotic was prescribed. This was documented in 23 of 127 cultures (18.1%). If the bacterial culture was positive and the bacteria were resistant to the empiric antibiotic choice, an appropriate antibiotic was prescribed for 3–4 wk based on the culture and sensitivity results. This was documented in 17 of 127 cultures (13.4%)." Spivack et al., JAAHA 2013

I was particularly interested by the fact that they reported a very low incidence of mild wound problems (5%) and, unless I missed it, no late-onset para-aural absessation or draining tracts.

This compares favourably to a review in VCNA in 2011 by Smeak which reviewed the former literature and found a reported immediate wound problem rate of 7%-31% and deep-seated infection problems in 2%-10% of cases. Could their liberal use of antibiotics contribute to this or do you think it more likely reflects improved surgical technique over the years and the earlier reports suffer from technical errors contributing to the higher complication rates? The only thing against the latter proposition to me is that in Spivack et al., the incidence of facial nerve issues post-op at 50% doesn't suggest that other complications related to surgical technique had been massively improved.

I laughed when I went to quote another recent technical article from UKVet 2012 as saying:

"Postoperative antibiotics are often continued for five days following the surgery if there was evidence of an otitis media at the time of surgery. Further antibiotics can then be prescribed depending on the results of bacterial culture and sensitivity."

The reason I laughed was that the author had taken the time to comment directly on my case! Thanks, Tim (This forum's an amazing resource - I'll be using it more I suspect )

Re: Multiresistant pseudomonas cultured from bulla

Tim Charlesworth — Fri, 27 Dec 2013 17:57:33 GMT

I wouldn't worry too much about the swab result at this stage unless you took the swab after flushing? If it was a pre flush swab then you've probably already flushed/cut away the problem. I've had quite a few TECA's that have yielded pre flush cultures that aren't sensitive to any ab's that we can give and I tend to get them as clean as I can preop (including flushing++ whilst in prep) and then using a sensible antibiotic postop (e.g. if pseudomonas Aeuriginosa then I'd use a double dose flouroquinolone as resistance tends to be concentration dependent). I never put in drains to TECA sites unless there is preoperative abscessation (e.g. horizontal wall rupture) as there is no proven benefit to doing so. I'm sure you'll be fine but if you have to go back in (e.g. para-aural abscess) then I know some surgeons used to leave gentamycin -impregnanted spheres behind. What I'e also heard of (if an abscess forms) is to do a VBO and place a penrose through the bulla (i.e. in laterally and out ventrally) which will allow ongoing drainage and provide some oxygenation to the site etc but I would emphasise having to do this would be very unusual!

Happy Christmas!

Tim

Re: Multiresistant pseudomonas cultured from bulla

John Flynn — Tue, 24 Dec 2013 19:36:31 GMT

I give pre-op gentamicin typically, then take a swab after all dissection done from deep in bulla prior to flushing; then usually keep hospitalised on gentamicin for 5 days post-op with iv fluids as added precaution (not really sure this is necessary). Adjustments made to that plan based on swab results and I do aim for at least 5-10 days post-op appropriate antibiotics, though would use longer course of 4-6 weeks if I thought had serious bulla osteitis (either if noted marked bulla changes on radiographs prior to surgery or if medial wall looked diseased intra-op).

Don't know if my appoach makes sense or not, but I figure that a week or 2 of gentamicin is small fish in the grand scheme of some of these cases that have been on months of antibiotics over a number of years, and if you shoved a pile of pseudomonas deep into any other surgical wound you'd worry about a post-op infection even in the absence of implants so not sure why wouldn't be concerned with TECA-LBO where contamination of deep tissue is inevitable and drainage will be poor and risk of biofilm formation if infection does set in prior to granulation tissue growing into bulla site to fill it? Does no-one else send cat bite abscesses home with a course of antibiotics even after flushing? Everyone surely would if you were suturing the skin shut well afterwards and I can't imagine that the eustachian tube provides sufficient drainage to make up for the fact that a contaminated wound has effectively been sutured closed in a TECA-LBO? (I don't routinely don't place drains, perhaps that makes a difference to approach)

I suspect you'd get away with not giving any further antibiotics, but I'd personally take in for 5 days for gentamicin (would make me feel better if nothing else, though I appreciate that's not a great reasoning!)

Re: Multiresistant pseudomonas cultured from bulla

Evelyn Barbour-Hill — Tue, 24 Dec 2013 14:59:58 GMT

[quote user="Beats"]Out of interest, do either of you just do the surgery and then send home without antibiotics afterwards or is it only because is 12days after surgery that don't think worth starting some with a suggested sensitivity now?[/quote]

I try to do 1 day before and 5 days after. Not sure it's essential but I haven't the nerve to try without.

Re: Multiresistant pseudomonas cultured from bulla

Michael Woodhouse — Tue, 24 Dec 2013 11:29:35 GMT

I personally don't do TECA/LBO but have done a reasonable number of LWRs and I will usually give a total of 5 days generic antibiotic cover, as not clean surgery - usually amoxy/clav but have used TMPS where money short (as seems to be a recurring theme with manky ears) and they all do fine.

You expect them to go a bit crusty.

Re: Multiresistant pseudomonas cultured from bulla

Beats — Tue, 24 Dec 2013 09:46:58 GMT

Thanks for advice.

Out of interest, do either of you just do the surgery and then send home without antibiotics afterwards or is it only because is 12days after surgery that don't think worth starting some with a suggested sensitivity now?

I've always given at least 3 weeks of appropriate antibiotics post-op before as concerned re deep-seated bulla osteitis as well as the fact that is hardly sterile surgery (quite the opposite!) and deep-seated wound infection post-op sounds nasty...

Re: Multiresistant pseudomonas cultured from bulla

Evelyn Barbour-Hill — Tue, 24 Dec 2013 01:16:05 GMT

[quote user="Michael Woodhouse"]

The problem went in the bin the day of surgery. I'd stop all abx and see what happens.

[/quote]

Inclined to agree.

Re: Multiresistant pseudomonas cultured from bulla

Michael Woodhouse — Mon, 23 Dec 2013 17:51:17 GMT

The problem went in the bin the day of surgery. I'd stop all abx and see what happens.