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Bacterial cystitis can be classified according to several definitions. Sporadic bacterial cystitis is defined as bacterial infection in the bladder that results in inflammation resulting in clinical signs such as pollakiuria, stranguria, dysuria and hematuria. … Read More
Bacterial cystitis can be classified according to several definitions. Sporadic bacterial cystitis is defined as bacterial infection in the bladder that results in inflammation resulting in clinical signs such as pollakiuria, stranguria, dysuria and hematuria.
Sporadic bacterial cystitis mainly occurs in otherwise healthy, non-pregnant females and less commonly in castrated males. Comorbidities such as uroliths, neurologic disease (IVDD) or endocrinopathies (diabetes mellitus, hyperadrenocorticism) are rarely present in this group.
Sporadic bacterial cystitis was previously referred to as simple uncomplicated lower UTI; however, the International Society of Companion Animal Infectious Diseases (ISCAID) Guidelines discourage the use of this term because it is often difficult to determine if the UTI is truly uncomplicated in dogs.
Dogs with more than 3 UTIs within 12 months are classified as having recurrent urinary tract infections (UTI). Recurrent UTIs are common in dogs. There are 2 major types of UTI recurrence: relapse and reinfection. The implications of relapse versus reinfection are important for management of recurrent UTI.
Relapses are defined as UTI recurrence of the same species and strain of microorganisms within days to weeks of completion of therapy accompanied by clinical signs of either pyelonephritis or lower urinary tract signs (LUTS).
Reinfections are recurrent UTI caused microorganisms that are different from the prior UTI. Subclinical bacteriuria (SBU) is a term used in human medicine (also called asymptomatic bacteriuria) to describe the presence of bacteria in the urine, as determined by a positive bacterial culture, in the absence of LUTS.
Subclinical bacteriuria (SBU) also occurs in dogs and cats. Subtle LUTS may be difficult to discern in small animals, so the distinction between SBU and UTI per se is not always easily defined. Subclinical bacteriuria has been variably reported in dogs and cats with prevalence rates in cats reported from 1% -29%.
In one study evaluating 101 healthy adult dogs, SBU was present in 8.9% of the dogs. Cats with SBU are typically older, female cats. Subclinical bacteriuria is also anecdotally reported more often in animals with endocrinopathies, chronic kidney disease (CKD), in animals treated with glucocorticoids or immunosuppressive agents, or in cats that have altered anatomy from perineal urethrostomy.
Deciding if or how to treat SBU in dogs and cats is often challenging. Treatment of SBU is not usually indicated (see below). Pyelonephritis is defined as an infection of the renal pelvis and surrounding renal parenchyma and is also referred to as upper UTI. Differentiation of pyelonephritis from lower UTI alone is not always easily determined.
Causes of recurrent UTI
Most UTIs occur from ascending bacterial infection from the vaginal vestibule or prepuce. There are normal host defenses that protect the urinary tract from ascending 2 infections. Interference with normal host defenses may contribute to recurrent ascending infections.
Potential contributing factors include urinary incontinence, incomplete voiding, urine stasis or reflux, disruption of or damage to the urothelium (urothelial carcinoma), anatomic abnormalities, morbid obesity, perivulvar dermatitis, alterations in immune competence, alterations of urine composition (glucosuria), or iatrogenic causes (perineal urethrostomy, indwelling urinary catheters).
Young adult cats rarely have bacterial UTI unless prior procedures (e.g., indwelling urinary catheters) predispose them to acquired UTI; older cats are more commonly affected by UTI (or SBU) because of concurrent diseases such as CKD, diabetes mellitus and hyperthyroidism that cause dilute urine or impaired immune competence.
Common causes of UTI relapse include inappropriate antibiotic use (incorrect antibiotic dose, duration, or poor owner compliance), persistence of infection within a nidus in the urinary tract (uroliths, neoplasia, pyelonephritis, prostatitis), and emergence of drug-resistant pathogens.
Common causes of reinfection include failure to eliminate predisposing causes for UTI (perivulvar hooding with perivulvar dermatitis, vaginal septa), urinary incontinence, and systemic illness (e.g., CKD, diabetes mellitus and hyperadrenocorticism). A rare cause of UTI is recto-urethral fistula, which presents usually with reinfections and multi-organism infections.
Bulldogs are the most commonly reported breed for recto-urethral fistulas. Diagnostics for sporadic bacterial cystitis For sporadic cystitis, urinalysis with quantitative aerobic urine culture of urine obtained by cystocentesis is recommended including antimicrobial susceptibility testing of any pathogen(s) isolated.
The presence of more than 103 cfu/mL of bacteria is considered clinically significant for urine specimens collected by cystocentesis. If the urine is well concentrated and glycosuria is absent, then further diagnostics, such as complete blood count (CBC), serum biochemical panel, and imaging studies, are not usually warranted in an otherwise healthy animal if the suspected infection is an isolated event.
We are current evaluating voided urine with and without perivulvar cleansing in female dogs as an alternative to cystocentesis, which may be useful for dogs with concurrent illness that makes cystocentesis less idea (e.g., urothelial carcinoma).
Diagnostic approach to animals with recurrent UTI The standard diagnostic evaluation for dogs with recurrent UTI should include history, physical examination, CBC, serum biochemistry profile, urinalysis, urine culture, abdominal radiographs and ultrasound (if available). The history should be reviewed to assess client compliance with prior treatments, diseases or drugs that could contribute to immunosuppression, evidence of urinary incontinence, or skin issues including perivulvar dermatitis.
Physical examination should include careful examination of the vulva and perivulvar skin for evidence of recessed or “hooded” vulva with perivulvar dermatitis that may contribute to reinfection of the urinary tract. Rectal examination should also be included as a standard part of the physical examination of dogs to evaluate the urethra for masses or uroliths that could contribute to recurrent UTI.
Abdominal radiographs should include the entire urinary tract including both kidneys and the entire urethra caudal to the pelvis. Cystoscopy is recommended for diagnostic evaluation for dogs with recurrent UTI if an underlying cause has not been identified during initial work-up. Cystoscopy helps rule out anatomic abnormalities, polyps, neoplasia or uroliths and permits mucosal biopsy for culture, cytology and histopathology.
Results of culture of bladder mucosa have yielded conflicting results in some studies. Cultures of tissue or uroliths are more sensitive than routine urine culture for detecting chronic UTI especially in dogs previously treated with antibiotics. Bacteria were isolated from bladder mucosal cultures or urolith cultures in 18 to 24% of dogs despite concurrent negative urine cultures.
Cultures of mucosal biopsies are readily obtained during cystoscopy. One study did not find an advantage in the culture of cystoscopic biopsies compared to urine culture. However, clinical experience suggests the benefit of such cultures in selected cases. Cytology and histopathology of cystoscopic biopsies are required to differentiate benign polyps and polypoid cystitis from neoplasia (most commonly urothelial carcinoma).
Correction of anatomic abnormalities (ectopic ureters, vaginal septal remnants) detected during cystoscopy may help prevent recurrent UTI. Treatment of sporadic cystitis Imitating antimicrobial therapy while awaiting culture results is most commonly recommended for dogs with sporadic cystitis.
There is evidence from humans that analgesics alone may be as effective as antimicrobials in uncomplicated bacterial cystitis; therefore, administration of NSAIDs pending urine culture results is an alternative approach to initiating empirical antimicrobial therapy.
For empirical therapy, the ISCAID Guidelines recommend amoxicillin as a reasonable first choice in most areas unless there is prior documentation of high frequency of bacterial resistance to amoxicillin.
While amoxicillin/clavulanic acid is also reasonable first tier antibiotic, evidence of benefit of clavulanic acid for treatment of UTI is lacking, even in UTIs with beta-lactamase producing bacteria, because high urinary concentrations of amoxicillin are usually achieved in animals with good renal function. (Some pharmacologists also suggest that urinary excretion of clavulanic acid is limited.)
Trimethoprim-sulfonamide is another first tier option, but may be associated with greater adverse effects in some dogs. However, the likelihood of adverse effects on first exposure is low with short courses of therapy recommended by ISCAID. Treatment for 3-5 days for sporadic bacterial cystitis is recommended in most cases as opposed to prior recommendations of 10-14 days.
Although one study documented that high dose short duration enrofloxacin was effective for sporadic cystitis, fluoroquinolones should be reserved for patients with documented need for this class of antibiotics or for animals with suspected pyelonephritis.
Treatment should be based on clinical cure, rather than microbiological cure; therefore, follow-up urine cultures are not recommended for animals with sporadic cystitis. Diagnostic and therapeutic approach for animals with recurrent UTI Treatment of recurrent UTI should include diagnostics to obtain a specific diagnosis followed by a systematic treatment approach.
Treatment of recurrent UTI should be based on aerobic culture and sensitivity testing of urine samples obtained by cystocentesis (or from culture of mucosal biopsies) rather than empiric antimicrobial 4 therapy.
Pending urine culture results, administration of NSAIDs may be considered to minimize clinical signs until culture results are available to guide antibiotic selection. By convention, treatment for dogs and cats with recurrent UTI has been recommended for up to 4 weeks, but a shorter course of therapy (10-14 days) is likely effective in these cases as well. (For re-infection rather than relapse, a short course of 3-5 days may be adequate.)
The clinician can consider obtaining a urine culture shortly after beginning the drug regimen and again 7 days after completing the antimicrobial. If a positive culture is found, further diagnostic tests to investigate for underlying comorbidities should be performed. Treatment should be based on clinical cure, rather than microbiological cure.
Therefore, follow-up urine cultures obtained after completion of antibiotics are not considered essential based on the ISCAID Guidelines. Urine cultures obtained during antibiotic therapy prove in vivo efficacy of the drug selected on the basis of the initial in vitro susceptibility testing.
This culture will be positive in dogs that have persistent infections that may show in vitro susceptibility to the administered antibiotics, yet treatment fails to resolve the resistant infection.
Positive cultures during antibiotic treatment may necessitate change of the antibiotic treatment especially in animals in which the clinical signs have not improved. Episioplasty may be effective for resolving re-infections that occur secondary to perivulvar dermatitis. Weight loss and control of active UTI are also recommended prior to episioplasty.
Resolution of relapsing UTI secondary to infected uroliths usually requires removal of the uroliths in order to achieve resolution of the UTI. Urinary incontinence may also contribute to recurrent UTI: if urine can leak out of the bladder, then bacteria may be able to ascend through the urethra from the lack of a tight seal.
Effective treatment of urinary incontinence may reduce the risk of recurrent UTI in dogs. For dogs with vaginal septal remnants, laser transection of the remnant may be beneficial to preventing future ascending UTIs.
Adjunct treatment for recurrent UTI
Alternative approaches for prevention and treatment of recurrent bacterial cystitis that have been investigated in human beings as well as animal models include the use of cranberry extract. The efficacy of cranberry extract in women has been mixed, but a recent meta analysis showed that cranberry extract may reduce recurrent UTI in otherwise healthy women.
While cranberry has been shown to prevent adherence of E. coli strains in in vitro studies, one study in dogs with intervertebral disk disease did not appear to reduce the risk of UTI in that placebo controlled trial. Live biotherapeutic products appear promising for treatment of recurrent UTI in humans and dogs.
Intravesical administration of nonpathogenic E. coli in human beings with recurrent UTI reduced symptoms of UTI and protected some patients from recurrent UTI after serial catheterizations which might reduce the need to antimicrobial therapy. In a recent veterinary study, intravesical administration of ASB E. coli 2-12 to dogs with recurrent UTI resulted in complete or nearly complete clinical cures in 4/9 dogs and 3 dogs also had microbiological cures at two weeks.
Three of these four dogs had ASB E. coli 2-12 isolated from their urine at day 14. Preventative antibiotic therapy used to be recommended, but newer information suggests that this approach may only reduce UTIs in the short-term and contributes to emergence of more resistant strains of bacteria and more resistant UTIs in the long term.
drug is utilized to treat or forestall certain urinary parcel contaminations. Macrodantin medicine is an antimicrobial that works by halting the development of microscopic organisms. It won’t work for viral contaminations (e.g., basic cold, influenza). Pointless use or abuse of
can prompt its diminished viability. Macrodantin ought not be utilized in youngsters short of one month old enough because of the danger of a specific blood issue.
Therefore, antibiotics should not be used for prevention of UTI. Pulse antibiotic therapy for 3-5 days every few weeks is also not an effective strategy for management of recurrent UTI. These misuses of antibiotics are likely to induce multiple drug resistance in the organisms causing the UTI and limit the number of effective antibiotic options available for treatment of future recurrent infections.
Subclinical bacteriuria (SBU): To treat or not to treat?
In humans with asymptomatic bacteriuria, treatment with antimicrobials is not always administered because of the potential adverse effects of the drugs, as well as concern for emerging antimicrobial resistance.
Although prospective studies regarding this issue in cats and dogs is very limited, SBU in dogs and cats may not always require treatment. One firm recommendation is to treat animals with SBU prior to and during urologic procedures (surgical or minimally invasive procedures) to minimize the risk of urosepsis. Enterococcus is one of the most commonly isolated organisms from dogs and cats with SBU.