P. 623

R. Dorsch1
1Medizinische Kleintierklinik, Department für klinische Tiermedizin, München, Germany
New information on bacterial Cystitis in Cats
Roswitha Dorsch, Dipl. ECVIM-CA, Dr. med. vet., Dr. habil.
Center for Clinical Veterinary Medicine, Ludwig Maximilian University Munich
Bacterial urinary tract infection (UTI) is an uncommon cause of feline lower urinary tract (LUTD) signs in young to middle-aged cats, but the incidence increases signi cantly in geriatric cats. Increased age and female gender have been identi ed as risk factors in several studies. In dogs, the majority of UTIs are classi ed as uncomplicated UTI, meaning that there is a sporadic infection of the bladder in an otherwise healthy individual with normal urinary tract anatomy and function. In cats, however, a high proportion of UTIs need to be classi ed as complicated UTIs because 80 – 83% of cats suffer from concurrent diseases, such as chronic kidney disease, hyperthyroidism, diabetes mellitus, or neurologic disease. An increased risk of UTI is also associated with urethrostomy, urolithiasis, and gastrointestinal disease such as constipation and megacolon (1). These diseases compromise the natural local or systemic defense mechanisms in a more profound or permanent way and predispose cats to bacterial UTIs. Apart from cats with typical clinical signs of LUTD, a considerable proportion of cats have asymptomatic or subclinical bacteriuria. Subclinical bacteriuria is de ned as the presence of bacteria in the urine, as determined by positive bacterial cultures in the absence of clinical and cytological evidence of UTI (2).
The diagnosis of UTI is based on clinical signs, urinalysis  ndings (hematuria, pyuria, bacteriuria) and a quantitative bacterial culture. Whenever possible, urine samples should be obtained via cystocentesis. In cats it is important to perform a stained urine sediment examination for a preemptive diagnosis of bacterial UTI. It has been shown that there is a very poor correlation between bacteriuria identi ed on an unstained wet urine sediment and bacterial culture results (3). In that study, the speci city of the wet-unstained sediment for true bacteriuria was only 56%, whereas the dry-stained sediment had a speci city of 99%. The gold standard
for diagnosing bacterial UTI is a quantitative urine culture from a cystocentesis-derived urine sample. Urine samples for culture/susceptibility testing should be refrigerated as soon as possible and processed in
a microbiology laboratory within 24 hours. Complete blood count, serum chemistry, T4, FIV-antibody and FeLV-antigen testing, and abdominal ultrasound and/or radiographs should be performed to identify a possible predisposing disorder.
Bacterial isolates
In the majority of feline UTIs, growth of a single
bacterial isolate is identi ed. Only 12 to 22% of the infections involve two or more isolates (4-6). The most commonly cultured bacterial species (spp.) in feline
UTI are Escherichia coli (E. coli), Enterococcus spp., Staphylococcus spp., and Streptococcus spp. In cats with diabetes mellitus, hyperthyroidism, or CKD, E. coli seems to be predominant (6, 7), while there is a higher proportion of Staphylococcus and Enterococcus spp.
in cats with LUT signs (8). Great caution is required when interpreting results of in vitro susceptibility testing of Enterococcus faecalis because of their inherent resistance to cephalosporins, clindamycin, and TSO. Despite in-vivo-susceptibility they are not effective in vivo.
Current guidelines for antimicrobial use for bacterial UTI in cats recommend the use of amoxicillin clavulanic acid for empirical treatment of uncomplicated UTI, or the
use of amoxicillin without clavulanic acid for infections with Gram-positive bacteria and amoxicillin clavulanic acid for infections with Gram-negative organisms. However, Gram staining will not be feasible in every veterinary practice. Two studies from Germany and Norway have shown that the susceptibility of bacterial urinary tract pathogens to ampicillin, the representative of the penicillins without clavulanic acid and assumed cross-resistance with amoxicillin, is low (58%) (9, 10).
On the other hand, there is concern in human and veterinary medicine that the use of broad-spectrum antimicrobials, such as amoxicillin with clavulanic acid, increases the prevalence of ß-lactamase-producing and methicillin-resistant bacteria. It is therefore advantageous to base the use of antimicrobials on the results of culture/susceptibility whenever possible. Treatment
with analgetic drugs (buprenorphine, NSAID in cases with normal hydration status and renal function) for alleviating clinical signs can be used while results of culture/susceptibility are pending. Postponing treatment is of course not possible if the patient has signs of pyelonephritis, such as fever and/or in ammatory leukogramm. The recommended duration of treatment is 7 days for uncomplicated infection and 28 days
An Urban Experience

   621   622   623   624   625