UTI Flashcards
Routes of infection
1) Ascending route
2) Hematogenous/Descending route
Ascending route
1) Pathogenesis
2) Possible causative organisms
1) Colonic/Fecal flora colonize at periurethral area / urethra –> ascend to bladder and kidneys –> invades tissues and causes inflammation & infection
2) E. coli, Klebsiella, Proteus
Descending route
1) Pathogenesis
2) Possible causative organisms
1) Organism causing infection at distant primary site enters bloodstream (bacteremia) –> organism invades urinary tract
2) S. aureus, M. tuberculosis
Host defense mechanisms to protect against UTI
1) Presence of bacteria in bladder stimulates micturition & increased diuresis –> emptying of bladder –> flush out bacteria from urinary tract
2) Antibacterial properties (antibacterial enzymes) of urine & prostatic secretions –> prevent multiplication of bacteria
3) Anti-adherence properties of bladder mucosa –> prevent attachment of bacteria –> prevents bacteria from invading tissues & causing infection
4) Inflammatory response by polymorphonuclear leukocytes (PMNs) –> phagocytose bacteria
Factors determining development of UTI
1) Competency of host defense mechanisms
2) Size of inoculum
- E.g. Urinary retention/Obstruction in urinary tract –> bacteria cannot be passed out –> increase size of inoculum –> increase risk of UTI
3) Virulence of pathogen
- E.g. Bacteria with pili are resistant to washout and anti-adherence mechanisms
Risk factors for UTI
1) Females > Males
- Due to shorter urethra
2) Sexual intercourse
- Increase colonization of bacteria at vaginal area, change vagina flora –> increase ascent of bacteria from vaginal area to urethra
3) Abnormalities in urinary tract, leading to urinary retention and/or backflow of urine
- E.g. BPH, urethral stricture, kidney stones, vesicoureteral reflux
4) Diabetes
- High glucose in urine –> increase bacterial growth
- Neuropathy –> urine retention
5) Neurological disorders
- E.g. stroke diabetes, spinal cord injuries
- Malfunction of urinary tract –> urinary retention
6) Catheterization, other mechanical instrumentation
7) Certain types of contraceptives
- E.g. Spermicides / Diaphragms –> alter flora in periurethral area/vaginal area –> increase bacterial colonization
- E.g. Unlubricated condoms / spermicidal condoms –> cause irritation –> increase bacterial growth
8) Positive family history
9) Previous history of UTI
10) Pregnancy
11) Anticholinergic drugs
- Causes urinary retention as a side effect
Subjective evidence for lower UTI (cystitis)
1) Dysuria
2) Urgency
3) Frequency
4) Nocturia
5) Gross hematuria
6) Suprapubic heaviness/pain
Subjective evidence for upper UTI (pyelonephritis)
1) Fever, rigors
2) Malaise
3) Headache
4) N/V
5) Positive renal punch
6) Abdominal/Flank pain
Objective evidence - Vital signs
1) Fever - Temperature ≥ 38 degC
2) Hypotension - SBP < 100 mmHg
3) Respiratory rate > 22 bpm
4) Heart rate > 90 bpm
5) Mental status changes
Objective evidence - Lab tests
1) TW > 10 x 10^9 / L OR TW < 4 x 10^9 / L
2) Increased neutrophils (normal: 45 - 75%)
3) Increased procalcitonin
4) Increased CRP (> 10 mg/L)
5) Increased ESR
Objective evidence - UFEME
1) Pyuria - WBC > 10 WBCs / mm3
- Indicates presence of inflammation
- Absence of pyuria –> unlikely to be UTI
2) Hematuria - > 5 HPF / gross
- Not specific for infection
3) Presence of microorganisms
4) Presence of WBC casts
- Indicates upper tract infection
Objective evidence - Chemical urinalysis
1) Nitrite
- Positive test indicates presence of GN bacteria
2) Leukocyte esterase (LE)
- Positive test indicates esterase activity
Urine collection methods
1) Midstream clean-catch
- Throw away first 20-30mL, collect midstream
2) Catheterization
3) Suprapubic bladder aspiration
When are urine cultures needed / not needed
May be necessary for:
1) Pregnant women
2) Men
3) Pyelonephritis
4) Catheter-associated UTI
5) Recurrent UTI (within 2 weeks / frequently)
NOT necessary in:
1) Uncomplicated cystitis
Causative organisms in:
1) Uncomplicated / community-acquired UTI
2) Complicated / healthcare-associated UTI
3) Catheter-associated UTI
4) Others
Uncomplicated / Community-acquired UTI:
- E. coli (> 85%)
- Staphyloccocus saprophyticus (5 - 15%)
- Enterococcus faecalis, Klebsiella, Proteus
Complicated / Healthcare-associated UTI
- E. coli (50%)
- Enterococci
- Proteus, Klebsiella, P. aeruginosa, Enterobacter
Catheter-associated UTI
- Short term (< 7 days): E. coli, Klebsiella (85% single organism)
- Long term (> 28 days): E. coli, Klebsiella, P. aeruginosa (95% polymicrobial)
Others
- S. aureus
- Candida/Yeast
Identifying uncomplicated UTI
No complicating factors
Usually in healthy, pre-menopausal, non-pregnant with no history suggestive of abnormal urinary tract
Identifying complicated UTI
UTI in men/children/pregnant women Complicating factors - Genitourinary instrumentation - Functional and structural abnormalities of urinary tract - DM - Immunocompromised
Identifying nosocomial UTI
Onset of UTI > 48h post admission
Identifying healthcare-associated UTI
UTI in:
- Hospitalized patients
- Underwent invasive urologic procedures in last 6 months
- Indwelling catheter
Healthcare risk factors
- Hospitalization in last 90 days
- Current hospitalization ≥ 2 days
- Nursing home resident
- Antimicrobial use in last 90 days
- Home infusion therapy
- Chronic dialysis
Identifying catheter-associated UTI
1) Presence of UTI s/sx AND
2) No other sources of infection AND
3) 10^3 cfu/mL of ≥ 1 bacterial species in:
- Single catheter urine specimen in patients with indwelling / intermittent catheter
- Midstream voided urine specimen from patient whose catheter has been removed in past 48h
Risk factors for catheter-associated UTI
1) Duration of catheterization
2) Colonization of drainage bag, catheter, periurethral segment
3) DM
4) Female
5) Renal impairment
6) Poor quality of catheter care, including insertion
Need to treat
Treat:
1) Symptomatic
2) Pregnant women (even if asymptomatic)
3) Patient going for invasive urologic procedure
- Antibiotics given as prophylaxis 12-24h before procedure (culture-directed)
Do NOT treat:
1) Asymptomatic
Empiric therapy for community-acquired uncomplicated cystitis in women
1st line:
PO Cotrimoxazole 800/160 mg BID x 3 days
PO Nitrofurantoin 50 mg QDS x 5 days
PO Fosfomycin 3 g single dose
Alternative: PO Cephalexin 500 mg BID x 5-7 days PO Cefuroxime 250 mg BID x 5-7 days PO Amoxicillin-Clavulanate 625 mg BID x 5-7 days PO Ciprofloxacin 250 mg BID x 3 days PO Levofloxacin 250 mg daily x 3 days
Empiric therapy for community-acquired complicated cystitis in women
Duration: 7 - 14 days
1st line:
PO Cotrimoxazole 800/160 mg BID
PO Nitrofurantoin 50 mg QDS
PO Fosfomycin 3 g every other day x 3 doses
Alternative: PO Cephalexin 500 mg BID PO Cefuroxime 250 mg BID PO Amoxicillin-Clavulanate 625 mg BID PO Ciprofloxacin 250 mg BID PO Levofloxacin 250 mg daily
Empiric therapy for community-acquired pyelonephritis in women
PO Ciprofloxacin 500 mg BID x 7 days
PO Levofloxacin 750 mg daily x 5 days
PO Cotrimoxazole 800/160 mg BID x 14 days
PO Cephalexin 500 mg BID x 10-14 days
PO Amoxicillin-clavulanate 625 mg TDS x 10-14 days
Empiric therapy for community-acquired pyelonephritis in women who are severely ill
IV Ciprofloxacin 400 mg BID OR
IV Cefazolin 1g q8h OR
IV Amoxicillin-clavulanate 1.2g q8h
+/- IV/IM Gentamicin 5 mg/kg
Empiric therapy for community-acquired cystitis (no concern for prostatitis) in men
Similar to complicated cystitis in women
Duration: 10-14 days
1st line:
PO Cotrimoxazole 800/160 mg BID
PO Nitrofurantoin 50 mg QDS
PO Fosfomycin 3 g every other day x 3 doses
Alternative: PO Cephalexin 500 mg BID PO Cefuroxime 250 mg BID PO Amoxicillin-Clavulanate 625 mg BID PO Ciprofloxacin 250 mg BID PO Levofloxacin 250 mg daily
Empiric therapy for community-acquired cystitis (concern for prostatitis) OR pyelonephritis in men
Duration: 10-14 days (6 weeks if prostatitis confirmed)
PO Cotrimoxazole 800/160 mg BID
PO Ciprofloxacin 500 mg BID
Empiric therapy for nosocomial / healthcare-associated pyelonephritis
Duration: 7-14 days
IV Cefepime 2g q12h +/- IV Amikacin 15 mg/kg/day
IV Imipenem 500 mg q6h
IV Meropenem 1g q8h
Empiric therapy for nosocomial / healthcare-associated pyelonephritis for less sick patients
Duration: 7-14 days
PO Ciprofloxacin 500 mg BID
PO Levofloxacin 750 mg
Empiric therapy for catheter-associated UTI
Duration: 7 days (prompt resolution of symptoms, defervescence in 72h) OR 10-14 days (delayed response)
IV Cefepime 2g q12h +/- IV Amikacin 15 mg/kg (single dose)
IV Imipenem 500 mg q6h
IV Meropenem 1g q8h
Empiric therapy for catheter-associated UTI - Mild infection
PO/IV Levofloxacin 750 mg daily x 5 days
Empiric therapy for catheter-associated UTI for women ≤ 65 years with catheter-associated UTI without upper urinary tract symptoms after an indwelling catheter has been removed
PO Cotrimoxazole 800/160 mg BID x 3 days
Prevention of catheter-associated UTI
1) Avoid unnecessary catheter use
2) Minimal duration
3) Long term indwelling catheter changed before blockage occurs
4) Closed system
5) Aseptic insertion technique
Antibiotics contraindicated in pregnancy
1) Ciprofloxacin
2) Cotrimoxazole (1st & 3rd trimester)
3) Nitrofurantoin (at term i.e. 38-42 weeks)
4) Aminoglycosides
Empiric therapy for pregnant women
Duration:
Asymptomatic / Cystitis: 7 days
Pyelonephritis: 14 days
Choice of antibiotics:
Similar to non-pregnant women (but without antibiotics C/I in pregnancy)
Adjunctive treatment
1) Paracetamol / NSAIDs
- Reduce pain, fever
2) Rehydration
- For vomiting
3) Phenazopyridine
- Topical analgesic effect on urinary tract mucosa –> symptomatic relief
- 100 - 200 mg TDS, for duration of symptoms
- ADR: N/V, orange-red discolouration of stool & urine
- C/I: G6PD deficiency
Unproven clinical benefit:
1) Urine alkalization
- Relieves discomfort
2) Cranberry juice
- Inhibit adherence of E. coli
- Clinical data suggest decreased incidence of UTI
3) Intravaginal estrogen cream
- Restore vaginal flora, reduce colonization of E. coli
- Decrease incidence of UTI in post-menopausal women
4) Lactobacillus probiotics
- Restore vaginal flora, reduce colonization of E. coli
- Recent small uncontrolled trial showed reduced recurrence in uncomplicated cystitis
Non-pharmacological management of UTI
Prevention
1) Drink plenty of fluids (6-8 glasses/day)
2) Urinate frequently & when you feel the urge
3) Urinate shortly after sex
4) Avoid diaphragms, spermicides, unlubricated/spermicidal condoms
5) Wipe from front to back after using the toilet, especially after bowel movement
6) Wear cotton underwear & loose fitting clothes
Monitoring
1) Resolution of signs & symptoms
- Should have improvement within 48-72h after initiation of effective antibiotics
- If patient fails to respond within 48-72h / Persistently positive blood cultures –> must carry out further investigation to exclude bacterial resistance, possible obstruction, renal abscess, other disease
2) Bacterial clearance
- Culture to document clearance of infection needed for pregnant women
3) ADR, allergies
