What is the cause of urinary tract infections?
most commonly E.COLI
- infection ascends from urethra to bladder
What are the causative organisms in UTI?
- E coli
- Staph Saprophyticus (in sexually active women)
- Klebsiella pneumoniae
- Proteus mirabilis -> gives urine pungent irritating smell & high pH due to ammonia (struvite stone)
- viruses -> immunocompromised patients & children
- > adenovirus, cytomegalovirus, & BK virus (hemorrhagic cystitis)
What are the predisposing factors to UTI?
- structural or functional abnormalities of the urinary tract
- > BPH, VU reflux, UB diverticulum
- > neurogenic bladder, urinary tract calculi
- gender -> higher risk in uncircumcised male infants
- pregnancy
- postmenopause -> decrease estrogen
- chronic constipation -> common in children
- prior condition
- > previous UTI
- > history of kidney surgery
- > immunosuppression
- > DM
- catheter-associated urinary tract infection (CAUTI)
How are UTIs classified according to clinical presentation?
- asymptomatic bacteriuria (ASB) -> bacteriuria without clinical features
- UTI -> bacteriuria & clinical features of UTI
How are UTIs classified according to location?
- UPPER UTI -> infection of kidneys & ureter (pyelonephritis)
- LOWER UTI -> cystitis &/or urethritis associated with prostitis in men
How are UTIs classified according to severity?
Uncomplicated
- infection without risk factors
Complicated
- infection in patients with risk factors -> pregnancy, postmenopause, abnormalities, immunosuppression
- infection associated with recent instrumentation or medical devices
- healthcare-associated UTIs
Urosepsis
- UTI leading to threatening organ dysfunction
What are the sources of infection?
Community acquired UTI
- acquired outside of healthcare setting
- manifests within 48 hours of hospital admission
Healthcare-associated UTI
- UTI in healthsetting
- catheter associated UTI (CAUTI)
- secondary to urinary tract instrumentation
When is a UTI considered recurrent?
- > or = 3 episodes of symptomatic, culture proven UTI in 1 year
- > or = 2 episodes in 6 months
What are the clinical features of urinary tract infections?
LOWER UTIs
- hematuria
- increased frequency
- urinary urgency
- suprapubic tenderness
- dysuria
UPPER UTIS - lower uti symptoms \+ - FEVER - flank pain - fatigue/malaise - nausea & vomiting - symptoms of pyelonephritis
What are more specific clinical features for UTIs in children, males, & old age?
Children
- urinary incontinence
- malodorous urine
- irritability, poor feeding, failure to thrive
Males
- pain in prostatic/perineal area
Older adults
- delirium/acute confusion
What is the approach for investigations to diagnose UTIs?
UNCOMPLICATED LOWER UTI in women
- typical symptoms -> treat without further diagnostics
- unclear history or symptoms -> urinalysis using urine dipstick/microscopy
COMPLICATED LOWER UTI in women
- obtain urinalysis & urine culture -> further diagnostics
LOWER UTI in men
- urinalysis & urine culture
- first febrile UTI -> CT or ultrasound
- consider referral to urology -> if diagnosis in unclear, hematuria, voiding difficulties, or recurrent UTI
What is the best initial laboratory study for UTIs?
URINALYSIS
- treatment should be started in uncomplicated cases directly
findings:
- pyuria -> WBCs -> positive leukocyte esterase ( >5 WBC/HPF or >8-10 WBC/mm)
- bacteriuria -> positive urinary nitrates (E. coli)
- leukocyte casts -> pyelonephritis
- microscopic or macroscopic hematuria
- alkaline urine pH > 8 & struvite crystals -> urease-producing organisms (PROTEUS, Klebsiella, Staph Saprophyticus)
- presence of squamous epithelial cells -> contamination
What are the indications for urine culture?
- suspicion of complicated UTI or healthcare associated UTI
- suspicion of pyelonephritis or urosepsis
- suspicion of uncomplicated cystitis with
- > history of recurrent UTIs
- > equivocal urinalysis
- > atypical symptoms
- > > 65 years of age
- > concern for multi resistant pathogens
- follow up cultures to test if treatment is working
When is a urine culture considered positive?
- > 10 5CU/mL in a clean catch specimen
- any organisms in a specimen obtained by SUPRAPUBIC ASPIRATION
in complicated or recurrent UTI -> culture should be taken before starting antibiotic treatment
When is using imaging modalities indicated in case of UTI?
- suspected GUT obstruction
- severe illness -> septic shock
- early recurrence of UTI -> within 2 weeks of treatment
- bacterial resistance
- recurrent complicated UTI
- men with evidence of febrile UTI
What is the most sensitive modality for initial imaging?
CT abdomen & pelvis
- no contrast -> urolithiasis
- IV contrast -> complications or GUT obstruction
When is ultrasonography used for kidneys & bladder?
- if there are contraindications to contrast or radiation
- for measuring post void residual urine in BPH
What are the risk factors of asymptomatic bacteriuria?
- age > 65 years
- diabetes mellitus
- spinal cord injury
- indwelling urethral catheter
- pregnancy
How is asymptomatic bacteriuria diagnosed & managed?
diagnosed with -> urinalysis with microscopy
management
- treatment recommended in -> pregnant women
- > patients undergoing endourological procedures - treatment not recommended in -> healthy non pregnant women
- > older adults & individuals with diabetes, indwelling catheters, or spinal cord injuries
How is an uncomplicated UTI treated?
FIRST-LINE
- nitrofurantoin for 5 days
- Trimethoprim/sulfamethoxazole (TMP-SMX) for 3 days
- Fosfomycin (single dose)
SECOND-LINE
- beta-lactam for 5-7 days
- amoxicillin/clavulanic acid
- oral cephalosporins (cefpodoxime, cefdinir, or cefaclor)
or
- ciprofloxacin for 3 days in resistant bacteria
How is an uncomplicated UTI treated in pregnant women?
- beta-lactam antibiotics -> amoxicillin calvulanate
- fosfomycin
How should complicated lower UTIs be treated?
hospitalization & initial IV treatment
- > severe systemic symptoms
- > inability to tolerate oral antibiotics
- > severe comorbidities
antibiotics
- Fluoroquinolones -> ciprofloxacin or levofloxacin
- Beta lactams -> cephalosporins (second or third generation) or extended spectrum penicillins
- Aminoglycosides -> gentamicin
How should recurrent UTIs be treated?
chemoprophylaxis -> in all women with recurrent uncomplicated UTIs
- continuous prophylaxis -> taken for 3-12 months (TMP-SMX)
- intermittent or postcoital prophylaxis -> TMP-SMX or Nitrofurantoin
What is CAUTI?
- symptomatic UTI with an indwelling catheter or in 48 hours after removal
- fever, pelvic or flank pain, hematuria, altered mental status, & lethargy
- catheter obstruction may result from colonization with urease producing organisms (proteus)
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