Urinary tract infection and subclinical bacteriuria

Question 1

Give a definition of urinary tract infection

Answer 1

Urinary tract infection refers to the adherence, multiplication and persistence of an infectious agent within the urogenital system that causes an associated inflammatory response and clinical signs
- more than 99% are caused by bacteria

Question 2

Give a definition of subclinical bacteriuria

Answer 2

Presence of a significant number of bacteria (>10^3 CFU/ml in a cystocentesis derived urine sample), with or without signs of inflammation in the urine sediment, in an animal that has no clinical signs referable to UTI

Question 3

Cite the different categories of significant bacteriuria in cats

Answer 3

Sporadic bacterial cystitis

Recurrent bacterial cystitis

Pyelonephritis

Subclinical bacteriuria

Bacteriuria in cats with indwelling urinary catheters

Bacteriuria in cats undergoing urological surgery or minimally invasive urological procedures and/or with urologic implants

Question 4

Give a definition of sporadic bacterial cystitis

Answer 4

Sporadic (fewer than three episodes in the preceding 12 months) bacterial infection of the bladder with compatible lower urinary tract signs in an animal with or without predisposing factors

Question 5

Give a definition of recurrent bacterial cystitis and give the subcategories of it

Answer 5

Three or more episodes of clinical bacterial cystitis in the preceding 12 months or two or more episodes in the preceding 6 months

Relapse
- infection with the same microorganism that recurs after successful treatment of the initial UTI

Reinfection
- infection with a different microorganism after the initial microorganism responded to therapy

Persistent infection
- persistently positive urine cultures with the same organism during treatment with appropriate antimicrobial agents

Superinfection
- infection with new organisms that develop during antimicrobial treatment for the initial infecting organism

Question 6

Give sub-classification of pyelonephritis

Answer 6

Acute pyelonephritis
- uncomplicated: no underlying comorbidity
- complicated: presence of a predisposing systemic disease or an anatomical/obstructive disorder

Chronic pyelonephritis

Question 7

Give three examples of complicated lower UTI

Answer 7

Emphysematous cystitis
- characterized by gaz accumulation within the bladder wall and lumen secondary to infection with glucose-fermenting bacteria (mainly E. coli)
- animals with diabetes mellitus are predisposed

Encrusting cystitis
- the hallmark of encrusting cystitis is adherent bladder mucosal plaques
- urea-splitting bacteria (e.g., Corynebacterium urealyticum) may lead to mineral precipitation, resulting in bladder wall encrustatio

Polypoid cystitis
- refers to mass-like proliferations or diffuse thickening of the bladder mucosa induced by chronic inflammation
- most commonly associated with Proteus sp. infections

Question 8

What are the risk factors for UTIs

Answer 8

UTIs are significantly more common in
- spayed female cats
- Abyssinian cats
- cats older than 10 years

A predisposing comorbidity can be identify in 80% of cats with UTI or subclinical bacteriuria
- the most common systemic comorbidities in affected cats are
- CKD
- diabetus mellitus
- hyperthyroidism

Question 9

What are the major host defences against bacterial colonisation

Answer 9

Frequent and complete voiding of an adequate urine volume

Presence of a normal resident microflora

A physiological urinary tract anatomy

Antimicrobial characteristics of the urine

Systemic immunocompetence

Question 10

Which pathogen is more often associated with subclinical bacteriuria and what are its characteristics

Answer 10

Enterococcus faecalis is more likely to be present in cats with sub-clinical bacteriuria than in cats with UTIs

E. faecalis has intrinsic resistance to numerous antibiotics including fluoroquinolone

E. faecalis form biofilms and can thus evade antimicrobials

Question 11

Which examination is important after pyelonephritis treatment and why

Answer 11

Cultures 1-2 weeks post-treatment are recommended

Question 12

what is the current recommendation of treatment for subclinical bacteriuria

Answer 12

Consider treatment of subclinical bacteriuria only in animals with suspected pyelonephritis, patients undergoing surgical procedures of the urinary tract, patients undergoing endoscopic procedures of the urinary tract, in diabetic animals if subclinical bacteriuria is thought to be the reason for insulin antagonism or ketosis