Dr. Lisa has great advice on UTIs:
From her website,
www.catinfo.org
Urinary tract infections can occur anywhere along the tract from the kidneys to the urethra. Most infections gain access to the bladder when bacteria travel up the urethra from the outside world. From the bladder, the infection can ascend to the kidneys.
Please note that when the abbreviation "UTI" is used, the 'I' must be defined. Does "I" mean infection? Or does it mean inflammation?
It is very important to understand the difference if we are to stop overusing antibiotics and start using more pain medications when cats exhibit signs of urinary tract problems.
Studies have shown that otherwise healthy cats (no kidney disease, diabetes, or hyperthyroidism) - that are showing signs of urinary tract discomfort - have only a ~1-2% chance of having a UT infection yet antibiotics are prescribed very frequently for these patients. The veterinary (as well as human) medical community needs to address this very serious problem involving the overuse/abuse of antibiotics.
Roughly 99% of these otherwise healthy cats have sterile (no infection) cystitis. This is because the feline is very good at saving water to stay hydrated which results in a very concentrated urine. (Urine Specific Gravity (USG) >1.040) Concentrated urine is a very hostile environment that does not readily support bacterial growth. Therefore......
Urinary tract infections are rare in cats without a concurrent disease such as kidney insufficiency, diabetes, or hyperthyroidism.
What about the other population of cats with diseases such as kidney insufficiency, diabetes, or hyperthyroidism? Cats with chronic kidney disease (CKD) and hyperthyroidism often produce a more dilute urine (USG <1.030) which is a friendlier environment for bacteria. Unregulated diabetic cats often have glucose (sugar) in their urine which makes a nice culture medium for bacteria.
However, even cats with CKD, hyperthyroidism, or diabetes that are showing signs of lower urinary tract disease have a less than 30% chance of having a urinary tract infection. (Several studies have been done in this area and the results have varied but all have shown less than 30%.) This fact illustrates why it is very important to run a culture and sensitivity.
Urine Culture and Sensitivity (C & S)
As described above in the Cystitis section, this is a two-part test that is used to check to see if an infection is present (culture) and what antibiotic(s) would be the most appropriate to use for the strain(s) of bacteria present (sensitivity).
Please note that I emphasized "if" in the previous sentence. It is very important to confirm that an infection actually exists rather than to subject your cat to the administration of an unnecessary, and potentially dangerous, antibiotic without proof that it is needed and is the correct one.
Culture results are reported over a period of 3 days - at a minimum. The typical sterile cystitis report will read:
24 hours - no growth
48 hours - no growth
72 hours - no growth
If there is an infection present, the report will read something like "moderate growth of e.coli - sensitivity pending." This means that the next report will give your veterinarian important information necessary to pick the best antibiotic for your cat's infection.
Cultures can be classified in 3 ways:
1) diagnostic - the initial culture before starting antibiotics to confirm that an infection is present and to identify the bacteria, assess the number of bacterial colonies to quantify the level of infection (cfu - colony forming units per milliliter of urine), and to determine the organisms' susceptibility to various antibiotics
2) therapeutic - performed 3-5 days after starting antibiotics (after a positive diagnostic culture) to assess antibiotic efficacy or it is sometimes performed 3-5 days before cessation of antibiotic administration
3) surveillance - performed 7-14 days after the last antibiotic dose to check for relapse or re-infection
Relapses are defined as recurrences caused by the same species and strain of microorganism that were found in the diagnostic culture within several weeks of stopping antibiotic therapy.
Re-infections are defined as recurrent UT infections caused by a different organism. The only way you can differentiate relapses from re-infections is to compare the results of the initial culture obtained prior to antibiotic usage to those of cultures obtained during and/or after discontinuation of the antibiotic.
Relapses represent antibiotic treatment failures that may result from improper antibiotic choice, dose and duration of therapy, lack of owner or patient compliance, failure of the patient to absorb an orally administered drug, deep-seated infections, failure to identify predisposing factors, or acquired drug resistance.
Re-infections, on the other hand, usually represents failure to recognize and eliminate predisposing factors associated with continuing dysfunction of host defenses, or UT infections caused by procedures such as catheterization or perineal urethrostomy (PU) surgery. Frequent re-infection is an absolute indication to evaluate the patient for anatomic, metabolic, and immunologic disorders that may compromise normal host defenses.
It is important to understand that when a cat has had his penis amputated (PU surgery) a vital barrier to infection has been removed.
For a patient's first time infection, therapeutic and surveillance cultures are not usually performed due to cost and added stress for the patient. However, they should be considered in all recurrent UT infection cases, otherwise the veterinarian and owner may find themselves running in circles.
To repeat an important point: Cats with a urine specific gravity above ~1.040 have a very low chance (~1-2%) of having a urinary tract infection.
Cats with a USG below ~1.030 have a higher chance of having an infection.
If a patient presents with lower urinary tract signs, and has a low urine specific gravity or is a diabetic cat that is spilling sugar in his urine, and if an in-house analysis of the urine indicates that an infection may be present, the patient may be started on a broad spectrum antibiotic pending the C & S result.
If the culture turns up negative, the antibiotic can be discontinued. Or if the culture comes up positive but shows that the bacteria are resistant to the antibiotic that has been chosen, the correct antibiotic can be started.
At least in these cases, the needless - or wrong - antibiotic will have been given for only 3 days instead of for a much longer period of time.
