Cat was diagnosed with a UTI, is a prophylactic use acceptable?

Question

My cat Stella was diagnosed with a UTI early in February. She is a senior cat of unknown age. The vet kept her for over a week treating her as it was a severe infection. I was allowed to finally bring her home with instructions on dosing her for 14 more days with liquid Clavamox 1.5ml twice daily x 14 days. I completed the course(Stella was none too happy about it) and brought her in 14 days later for a urinalysis. That test still showed bacteria in her urine. The vet had me bring her in for another urine sample.  This test which would identify the bacteria and which drug would be the best to treat it took 5 more days. When it came back it was the same bacteria suspected in the beginning. The best drug for treatment, Clavamox. This time it was the 62.5 mg pill twice daily for 14 days. (Stella was not happy withthis either) I was told to bring her back in after day 10 on the med to test again. The test results came back that she had cleared the bacteria. I was then told that even though Stella had finished the 14 days required the vet wanted me to continue dosing her profolacticly for another 14 days. I'm afraid that this is possibly over prescribing the antibiotic. When I did ask the vet, she said because of Stella's advanced age, this would insure the UTI would not have a reoccurance.  This seems to me that Stella  might develop an immunity to any efficacy the drug might have going forward.  My question is about the medication usage. Is a prophylactic use acceptable, especially in Stella's case? Please let me know. As of now I am continuing as directed.  Thank you for any help you can provide, Sherrie McGee

Dr. Chris Vanderhoof, DVM, MPH · Accepted Answer

Hi Sherrie,

It sounds like your vet may have been concerned about a pyelonephritis, or kidney infection and not just a run of the mill UTI, if it was as serious as described. I would suspect that they felt it possible when the bacteria was still present after the first 14 days, that there could have been a compliance issue where Stella may have been spitting out portions of the liquid Clavamox dose and was not getting the full dose each time. As you said, she was none too happy with it, as many cats may not be.

Fortunately, it sounds like the culture indicated that no antibiotic resistance to Clavamox was present, so it could still be used.

It’s hard to say if the tablet form was more effective because she was getting the full dose, or if the infection just took a longer time to clear. Pyelonephritis, if that’s what was present, can take longer courses of antibiotics than basic UTIs.

I don’t think it’s unreasonable to treat for two extra weeks, since you can’t always be 100% certain such a serious infection is gone from a urine sample alone. Sometimes, we recheck a culture again as well. I have treated similar types of infections longer too, as long as there’s a culture to back it up. There is a greater risk of bacterial resistance present if the Clavamox is stopped when there is still even a small population of that bacteria left. These remaining bacteria are the hardiest and most likely to develop resistance if they’re not killed. Probiotics can be helpful to counteract the effects of a longer antibiotic course on the rest of the body.

Two extra weeks is unlikely to impart antibiotic resistance in the same way that some kind of long-term prophylactic antibiotic use might, where an antibiotic is being used repeatedly at intervals for months or years to “prevent” an infection from occurring. That I certainly would not agree with, but I’d feel that’s different from extending an antibiotic course for 14 more days.