small animal med- urinary tract infections

does presence of bacteria in the urine indicate infection?

no

which structures of the urinary tract are considered sterile environments?

kidneys, bladder, and proximal urethra are considered sterile

what is the prevalence of UTIs in dogs?

14% of dogs will have a UTI in their lifetime

spayed females and older dogs (>7 years) are at in increased risk

are UTIs more common in cats or dogs?

dogs

when are UTIs seen in cats?

usually in older cats with co-morbidity (CKD, hyperthyroidism, diabetes)

occurs in young cats who have had urinary catheterization or PU surgery

do the majority of young cats that present with lower urinary tract signs usually have bacterial cystitis?

no, these cats likely have either stones or FIC (feline idiopathic cystitis)

what are the lower urinary tract clinical signs?

-stranguria

-pollakiuria

-periuria (urinating in inappropriate places)

-hematuria

-licking at urethral opening

what is the most common bacterial uropathogen?

e. coli

what is the definition of sporadic bacterial cystitis?

bacterial infection of the bladder with LUT signs

fewer than 3 episodes in the preceding year

which animals is sporadic bacterial cystitis seen in?

usually healthy pets (non-pregnant females, neutered males)

also animals with no urinary tract anatomical and functional abnormality or relevant comorbidities

how is sporadic bacterial cystitis diagnosed?

1. presence of LUT signs with evidence of cystitis (hematuria, pyuria, bacteria) on urinalysis

2. urinalysis performed in all cases to screen for cystitis

3. aerobic culture preferred (via cystocentesis) in dogs (perform in all cats to confirm true infection)

how are antibiotics chosen for treatment of sporadic bacterial cystitis?

-guided by suspected bacterial species on urinalysis (pH, morphology)

-guided by culture and sensitivity if available

-choose weaker and safer drug

what does it mean to choose a 'weaker' antibiotic?

weaker drugs= noncombination drugs, earlier generation drugs

what does it mean to chose the 'safer' antibiotic?

drugs with wide margin of tolerance, low risk of systemic effects

what is the likely uropathogen causing bacterial cystitis with an acidic pH (at or below 7) and rod bacteria?

e. coli

what is the likely uropathogen causing bacterial cystitis with an acidic pH (at or below 7) and cocci bacteria?

enterococcus spp.

what is the likely uropathogen causing bacterial cystitis with an alkaline pH (above 7) and rod bacteria?

proteus spp

what is the likely uropathogen causing bacterial cystitis with an alkaline pH (above 7) and cocci bacteria?

staphylococcus spp

when is empirical antibiotic therapy in lieu of culture justified for treatment of sporadic bacterial cystitis?

justified if:

-limited previous antimicrobial exposure

-no treatment of UTI in past 3 months

what are the empirical antibiotic choices for sporadic bacterial cystitis?

amoxicillin, TMS

second line: fluoroquinolones, 3rd gen cephalosporins

what is the duration of antibiotic therapy for sporadic bacterial cystitis?

5 days

how should patients with sporadic bacterial cystitis be monitored?

-monitor for resolution of clinical signs

-post-treatment UA and urine culture not required if clinical resolution of LUT signs

when is further investigation warranted when monitoring the treatment of sporadic bacterial cystitis?

-lack of clinical response within 48 hours of starting antibiotic

-relapse of clinical signs shortly after discontinuation of antibiotics

what is the definition of recurrent bacterial cystitis?

diagnosis of 3 or more episodes of clinical bacterial cystitis in the preceding 12 months or 2 or more episodes in the preceding 6 months

what is recurrent bacterial cystitis the result of?

result of relapsing or persistent infection or reinfection

how are relapsing/persistent infections and reinfections differentiated in cases of recurrent bacterial cystitis?

if isolate is different from previous organism isolated→ reinfection

if isolate is same organism with the same susceptibility pattern→ relapse or persistent infection

what are risk factors and comorbidities that predispose dogs and cats to UTIs?

-endocrinopathy

-kidney disease

-obesity

-abnormal vulvar conformation

-congenital abnormalities of urogenital tract

-prostatic disease

-bladder tumor

-polyploid cystitis

-urolithiasis

-immunosuppressive therapy

-rectal fistula

-urinary incontinence/retention

what does the work-up exam include for patients with recurrent bacterial cystitis?

-genital exam

-chemistry panel

-UA and culture

-radiographs

-ultrasound

-refer for cystoscopy

what is the treatment for recurrent bacterial cystitis?

-give NSAID and/or empirical abx pending urine culture

-avoid repeat use of abx that the pet has not fully responded to in the past

-reassess once you get C&S results

-treat with chosen antibiotics for 7-10 days

what are the treatment goals of recurrent bacterial cystitis?

clinical cure with minimal risk of adverse effects of antibiotic

microbiologic cure is desirable but not always possible

which animals is bacterial prostatitis most commonly seen in?

male intact dogs

what are the common etiological agents of bacterial prostatitis?

similar bacteria as found in bacterial cystitis

brucella canis is a zoonotic cause of prostatitis

what are clinical signs of bacterial prostatitis?

same as bacterial cystitis, plus:

-fever

-malaise

-inappetence, vomiting, diarrhea, tenesmus

-septic shock

how is prostatitis diagnosed?

-per rectum palpation of prostate

-CBC/chem/UA/urine culture

- +/- ultrasound to assess size and structure of prostate

- +/- cytology of prostatic wash or prostatic fluid collection by FNA

what is the challenge of treating prostatitis with antibiotics?

the blood prostate barrier limits penetration of antimicrobials, especially in chronic prostatitis when the barrier may be less compromised

what antibiotics are used to treat bacterial prostatitis?

lipid soluble antibiotics:

-first line or empiric therapy: fluoroquinolone (except ciprofloxacin)

-second line: clindamycin or macrolides

how long is antibiotic therapy for bacterial prostatitis?

4 weeks

which antibiotics should be avoided for treatment of bacterial prostatitis?

amoxicillin, cephalosporins, aminoglycosides, tetracyclines (these dont cross blood prostate barrier)

besides antibiotics, what are other treatments for prostatitis?

-castration

-drain prostatic abscess

what is the definition of pyelonephritis?

infection of renal parenchyma that occurs from ascending infection (more commonly) or bacteremia due to animal being septic

what is the most common pathogen isolated from pyelonephritis?

e. coli

what are clinical signs of pyelonephritis?

systemic signs of illness and renal pain

what lab abnormalities are seen with pyelonephritis?

-bacteriuria, pyuria, hematuria

-inflammatory leukogram

-azotemia

-glucosuria, proteinuria, cellular casts (tubular epithelial, RBC, WBC)

how is pyelonephritis diagnosed?

difficult to prove diagnosis without renal biopsy or pyelocentesis

a presumptive diagnosis is made based on systemic signs, positive urine culture, and azotemia

why should you always perform a urine culture in AKIs or acute on chronic kidney disease?

to screen for potential pyelonephritis

culture even if quiet urine sediment or no LUT signs present

what abnormalities may be seen on ultrasound in patients with pyelonephritis?

U/S findings are nonspecific:

-renal pelvic dilation (+/- echogenic fluid)

-dilated ureter

-blunting of renal papilla

-hyperechoic retroperitoneal fat around kidney

how is pyelonephritis treated?

-start tx ASAP while awaiting culture results

-treat for AKI (IV fluids, monitor UOP)

-antibiotics for 14 days

which antibiotics are used for treatment of pyelonephritis?

-fluoroquinolone (oral and injectable)

-cefpodoxime (oral)

-ceftazidime or cefotaxime (injectable)

why should you use enrofloxacin with caution in cats with kidney disease?

do not exceed 5mg/kg once a day

cats w/ kidney disease may have reduced renal excretion of drug, so can accumulate and cause toxicity

what other differentials should be considered if there is no improvement in systemic signs/hematology/azotemia within 72 hours of antibiotic therapy for treatment of pyelonephritis?

-subclinical neoplasia

-renal neoplasia

-ureterolith

-ischemic injury

-lepto (dogs)

how are patients treated for pyelonephritis monitored?

recheck chemistry panel, urinalysis, and urine culture 1-2 weeks after cessation of antibiotics

what is the definition of subclinical bacteriuria?

presence of bacteria in urine in the absence of clinical evidence of infectious disease (ie no LUT or AKI signs)

which animals is subclinical bacteriuria seen in?

occurs in both healthy pets (dogs >cats) and those with disease (diabetes, immunosuppression, CKD)

what are the most common isolates of subclinical bacteriuria?

enterococcus species more common than e. coli

should you treat animals with subclinical bacteriuria?

tx is discouraged for these animals, there is no evidence that tx improves outcome

tx also contributes to abx resistance and recolonization often follows abx tx

how should animals with subclinical bacteriuria be monitored?

if no tx indicated (as in most cases), ask owner to monitor for LUT signs (if LUT signs develop, recheck UA and urine culture)

recheck in 3-6 months in pets with comorbidities