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110.e2 Bacteriuria, Subclinical

Bacteriuria, Subclinical
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• Anything that interferes with the normal
BASIC INFORMATION
protective mechanisms will predispose to • CBC and biochemical profile: identify
potential disorders that might predispose to
Definition microbial colonization of the urinary tract cystitis.
The isolation of bacteria (in excess of quantities (see Risk Factors).
potentially explained by contamination) on • Uropathogenic microbes possess virulence Advanced or Confirmatory Testing
routine microbial culture from the urine of a factors that facilitate their ability to adhere Investigate potential predisposing factors, as
dog or cat with no identifiable signs of cystitis. to and colonize the urinary epithelium. appropriate.
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Bacteria quantities < 10 CFU/mL in dogs and Colonizing microbes can 1) be eliminated
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10 CFU/mL in cats on free-catch urine samples, by the host, 2) remain in the urinary tract TREATMENT
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quantities < 10 CFU/mL from catheterized without causing inflammation or illness, or
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samples in dogs, or quantities < 10 CFU/mL 3) result in cystitis. Cystitis is defined as an Treatment Overview
from samples obtained by cystocentesis may be infection of the bladder with accompanying What circumstances, if any, warrant antimi-
due to contamination. signs of dysuria, pain, urinary urgency, or crobial therapy for bacteriuria in pets with no
hematuria. reported clinical or physical abnormalities
Synonyms • In the past, the urinary bladder was thought related to cystitis remains unknown. In humans,
Occult urinary tract infection, asymptomatic to be sterile during health. Actually, the urine subclinical bacteriuria is treated only in a few
bacteriuria, subclinical urinary tract infection of healthy humans, dogs, and likely cats specific circumstances (e.g., pregnancy, planned
contains a large variety of microorganisms urologic interventional procedures, immediate
Epidemiology (i.e., urinary microbiome). Most of these period after renal transplantation). Several
SPECIES, AGE, SEX microbes are identified only using sophisti- meta-analyses conclude that antimicrobial
Seemingly more common in older animals cated techniques and not on routine urine treatment of people with asymptomatic (i.e.,
culture. subclinical) bacteriuria does not reduce the
RISK FACTORS • The clinical significance of microbes identi- incidence of symptomatic cystitis, complications
Dilute urine for any reason, immunosuppression fied on routine culture from appropriately of cystitis such as pyelonephritis, or death
or immunocompromise, endocrinopathy (e.g., collected urine in animals with no signs of compared to no treatment.
diabetes mellitus, hyperadrenocorticism), cystitis, no complications of cystitis such as
incomplete urinary emptying (e.g., upper or urolithiasis (p. 1016). And no evidence of Acute General Treatment
lower motor neuron disease affecting the inflammation on urine sediment examination Because there is a paucity of data regarding the
bladder), urinary incontinence, anatomic defects remains to be determined. need for treatment, the following is based on
of the urinary tract (e.g., recessed vulva, ectopic the author’s opinion. Consider implementing
ureter, diverticula) antimicrobial therapy (p. 232) in the following
Clinical Presentation DIAGNOSIS circumstances:
• Urine is cloudy, opaque, or malodorous, or
DISEASE FORMS/SUBTYPES Diagnostic Overview there is an active urine sediment (i.e., > 5
By definition, this disorder is identified by urine By definition, subclinical bacteriuria is identified WBC/hpf, hematuria unexplained by sample
culture in animals without clinical signs typical on urine culture from an animal absent histori- collection, numerous rods or cocci/hpf,
of cystitis (p. 232). Because there are no signs cal or physical examination evidence of cellular casts)
to prompt urine culture, most cases are identified cystitis. • Conditions that might make dysuria difficult
after bacteria are visualized on sediment exam to observe (e.g., paresis that might interfere
during routine urinalysis or after screening urine Differential Diagnosis with the animal’s pain sensation, outdoor-
culture is performed on an animal with a disease • Sample contamination only dog unobserved during urination)
condition known to predispose to cystitis (e.g., • Cystitis • Underlying disease that might be negatively
diabetes mellitus, paraparesis). impacted by bacterial urinary infection (e.g.,
Initial Database chronic kidney disease [cats especially],
HISTORY, CHIEF COMPLAINT • Review history with pet owner, specifically diabetes mellitus).
Incidentally discovered; history may be remark- inquiring about dysuria, stranguria, perineal The author avoids antimicrobial therapy
able for a disorder known to predispose to licking or other behavioral changes, inap- for subclinical bacteriuria in the following
bacterial cystitis propriate urination (e.g., urinating outside circumstances:
a litter box or on a floor), urinary frequency, • Factors that predispose to bacteriuria cannot
PHYSICAL EXAM FINDINGS urinary volume, and character of the urine be corrected (e.g., permanent paraparesis)
None related directly to bacteriuria. (e.g., color, odor). • Bacteria isolated are resistant in vitro to
• Urinalysis for specific gravity, pH, glucose, multiple antimicrobial drug classes or for
Etiology and Pathophysiology and sediment which in vitro susceptibility exists only to
• The urinary bladder is protected from infec- ○ Poorly concentrated urine can predispose parenteral, expensive, or very broad-spectrum
tion by anatomy and function (e.g., intact to bacteriuria or cystitis. drugs. Enterococcus spp often fit these criteria.
epithelial barriers, unidirectional urine flow ○ Glucosuria can predispose to bacteriuria • If subclinical bacteriuria is recognized within
emptying the bladder periodically, urethral or cystitis. several months of completion of a course of
sphincters), innate defenses (e.g., epithelial ○ Alkaline pH often identified with uro- antimicrobial therapy
cathelicidin, defensins), acquired immune pathogens (e.g., Proteus spp, Staphylococcus • The bacteria isolated is not a known uro-
defenses (e.g., immunoglobulin A), and spp) pathogen. The most common uropathogens
chemical properties of the urine (e.g., ○ Active sediment (p. 1390) can suggest are Escherichia coli, Staphylococcus spp,
concentration, pH, deficiency of nutrients inflammation associated with cystitis Streptococcus spp, Enterococcus spp, Proteus
needed for microbial growth). rather than subclinical bacteriuria. spp, Klebsiella spp.

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