Urinary Tract Infections Flashcards
How does prevalence of UTI vary with age & gender?
0-6mths: Males >
- Higher rate of structural/functional abnormalities
1-adult: Females >
- Shorter urethra, easier access for bacteria; Males have extra protection from antibacterial secretions from prostate
Elderly: Equal
- Comorbidities, increased usage of cahether
Normal host defense mechanisms
- Bacteria in bladder stimulates micturitoin -> Increases diuresis -> Increased emptying of bladder
- Antibacterial properties of urine & prostatic secretion
- Anti-adherence mechanism -> Prevent bacterial attachment
- Inflmm response with polymorphonuclear leukocytes (PMNs) -> Phagocytosis -> Prevent/control spread
Different types of UTIs?
Pyelonephritis, Cystitis, Catheter-associated, Urethritis, Prostatitis, Epididymitis
Pathogenesis (Routes of Infection)
1) Ascending
- colonic/fecal flora colonise periurethra/urethra & ascend to bladder/kidney (eg. E.coli, Klebseilla, Proteus)
- Females > risk (shorter urethra)
2) Descending (< common)
- Organism at distant primary site -> Bloodstream -> Urinary Tract -> UTI
- Eg. Staph aureus, mycobacterium tuberculosis
Factors affecting developement of UTI
1) Competency of host defense mechanism
2) Size of inoculum
3) Virulence/Pathogenicity
Risk factors for UTI
- Females
- Sexual intercourse (Incr colonisation of bacteria @ vaginal site)
- Abnormalities of urinary tract (Incr urinary retention)
- Neurologic dysfunctions
- Anti-cholinergic drugs
- Catheterization/ Other mechanical instrumentation (can harvest bacteria in medical devices)
- Diabetes (Neuropathy, can have urinary retention)
- Pregnancy
- Use of diaphragms/spermicides (Can alter flora of periurethra area)
- Genetic association
- Previous UTI
Non-pharmacological interventions for UTI
- Drink lots of fluid (6-8 glasses/day)
- Urinate frequently whenever you feel the urge
- Urinate shortly after sex
- Wipe from front to back especially after bowel movement (Females)
- Wear cotton underwear & loose-fitting clothes, keeo area dry
- Modifying birth control method (Soermicidal & unlubricated condoms can increase bacterial growth)
Non-pharmacological interventions for UTI
- Drink lots of fluid (6-8 glasses/day)
- Urinate frequently whenever you feel the urge
- Urinate shortly after sex
- Wipe from front to back especially after bowel movement (Females)
- Wear cotton underwear & loose-fitting clothes, keep area dry
- Consider modifying birth control (Unlubricated/Spermicidal condoms increase irritation, may help bacteria grow; Diaphragm/Spermicide can increase bacteria growth)
Classification of UTI
1) Complicated
- Potential for serious outcomes, risk for therapy failure
- Presence of complicating factors
2) Uncomplicated
- Healthy, premenopausal, non-pregnant women with no hx suggesting abnormal urinary tract
Symptoms of lower UTI (Cystitis)
- Dysuria, urgency, frequency, nocturia, gross hematuria, suprapubic heaviness or pain
Symptoms of upper UTI (Pyelonephritis)
- Costovertebral tenderness (Renal punch)
- Flank pain
- Fever, reigors, HA, N/V, Malaise
Note: Elderly may not present specific urinary symptoms instead just more drowsy, less alert, general GIT symptoms
Methods to collect urine
1) Midstream clean-catch
2) Catheterization
3) Suprapubic bladder aspiration
Microscopic analysis of UFEME
- WBC: > 10 WBCs/mm3 = pyuria
- > Signifies presence of inflmm (no pyuria = unlikely UTI)
- Presence of RBC (Hematuria) (frequent but non-specific)
- Identify bacteria/yeast using Gram stain
- WBC casts indicate upper tract infection/disease
What does chemical urinalysis (dipstick) test for?
Nitrite
- Positive test detects for Gram (-) bacteria (at least 10^ bacteria/mL)
- False -ve: Gram (+), P.aeruginosa, frequent voiding, dilute urine
Leukocyte esterase
- Positive test detects esterase activity of leukocytes in urine
- Correlates with significant pyuria
Pathogen for Uncomplicated Cystitis
- E. Coli (Most common)
- Staphylococcus Saprophyticus
- Enterococcus, Klebsiella, Proteus
Pathogen for Complicated/ Healthcare-associated Cystitis
- E. Coli (Most common)
- Enterococci
- Proteus, Klebsiella, Enterobacter, P. aeruginosa
Unlikely pathogens for UTI
S. Aureus: Bacteremia, to consider other primary sites of infection
Yeast/Candida: Possible contaminant
Exceptions to treat asymptomatic UTI
1) Pregnancy
- Reduces developement for pyelonephritis, risk of preterm labour & low birth weight infant
2) Invasive urologic procedures with mucosal trauma
- Antibioitics given as prophylaxis to prevent postoperative bacteremia & sepsis
- Obtain culture, start based on culture & sensitivity 12-24hrs BEFORE procedure
Empiric antibiotics for uncomplicated cystitis in women (community-acquired)
1st line:
- PO Cotrimoxazole 800/160mg BD x 3d
- PO Nitrofurantoin 50mg QID x 5d
- PO Fosfomycin 3g single dose
- PO Beta-Lactams x 3-7days
- -> Cefuroxime 250mg BD/ Cephalexin 500mg BD/ Augmentin 625mg BD
- PO Fluoroquinolones x 3days [not recc]
- -> Ciprofloxacin 250mg BD/ Levofloxacin 250mg daily
Empiric antibiotics for complicated cystitis in women
- Same as uncomplicated cystitis -
- Longer: 7-14days
- Fosfomycin: PO 3g EOD x 3 doses
Adverse effects of Cotrimoxazole
- Photosensitivity
- Hemolytic anemia (G6PD Deficiency)
- Megaloblastic anemia, leukopenia & theombocytopenia (Give folinic acid)
- N/V
- Rash
Caution in 1st & last trimester of pregnancy
Empiric antibiotics for community-acquired Pyelonephritis in women
1st line:
- PO Fluoroquinolones
–> Cipro 500mg BD x 7days/
Levo 750mg OD x 5days
- PO Cotrimoxazole 160/800mg BD x 14days
- PO Beta-lactam x 10-14 days
–> Cephalexin 500mg BD/
Augmentin 625mg TDS
Severely ill requiring hospitalization/ Unable to take oral drug:
- IV Ciprofloxacin 400mg BD
- IV Cefazolin 1g Q8h
- IV Augmentin 1.2g Q8h
ADD/or IV/IM Gentamicin 5mg/kg for ESBL-producing E.Coli coverage
Empiric antibiotics for community-acquired UTI in men
- Same as complicated cystitis but for LONGER DURATION -
Empiric antibiotics for prostatitis/ pyelonephritis in men
Prostatitis: Localised pain/ pain on ejaculation
- PO Ciprofloxacin 500mg BD
- PO Cotrimoxazole 800/160mg BD
Duration: 10-14 days, longer duration if prostatitis confirmed (6 weeks)
Empiric antibiotics for Nosocomial/Healthcare-associated Pyelonephritis
Nosocomial: Onset >48h post-admission
Healthcare-associated: Hospitalized/ Underwent invasive urological procedure in the last 6mths
- To consider possibility of Pseudomonas aeruginosa & resistant bacteria*
- IV Cefepime 2g Q12h +/- IV Amikacin 15mg/kg/d
- IV Imipenem 500mg Q6h
- IV Meropenem 1g Q8h
For less sick:
- PO Levofloxacin 750mg
- PO Ciprofloxacin 500mg BD
Duration: 7-14days
What is the most common cause for nosocomial UTI?
Catheter-associated UTI
- Presence of symptoms/signs compatible with UTI with no other identified sources of infection frm pt whose catheter has been removed within previous 48h
Risk for Catheter-associated UTI?
- Duration (3-5% chance/day)
- -> Short-term (<7days): 85% Single organism
- -> Long-term(>28days): 95% Polymicrobial
- DM
- Female
- Renal function impairment
- Poor quality of catheter care, including insertion
- Colonisation of drainage bag, catheter & periurethral segment
Treatment of asymptomatic Catheter-associated UTI?
NOT RECOMMENDED except prior to traumatic urological procedures
- ALWAYS consider removing catheter
- If catheter has been placed for >2weeks at onset of CA-UTI & is still consider, should replace catheter to hasten resolution of symptoms & reduce risk of subsequent CA-bacteriuria
Treatment of symptomatic Catheter-associated UTI?
- Consider observation b/f immediate therapy if patient stable & fever low grade
- Urine culture MUST be taken
- Start empiric therapy, adjust after culture & sensitivity testings
Antibiotic treatment of symptomatic Catheter-associated UTI
- IV Imipenem 500mg Q6h
- IV Meropenem 1g Q8H
- IV Cefepime 2g Q12h +/- IV Amikacin 15mg/kg (1 dose)
Mild cases:
- PO/IV Levofloxacin 750mg X 5d
Women <65 with CA-UTI w/o upper ut symptoms after indwelling catheter removed:
- PO Cotrimoxazole 800/160mg BDS X 3d
Duration: 7 days
(10-14 days if delayed response)
Prevention of Catheter-associated UTI
- Avoid unnecessary catheter use
- Minimal duration
- Long-term indwelling catheter changed before blockage
- Use closed system
- Aseptic insertion technique
AVOID:
- Topical antiseptic/antiobiotics
- Prophylatic antiobiotics
- Chronic supressive antibiotics
Antibiotics to avoid in pregnancy
1) Ciprofloxacin
- Reports of fetal cartilage damage & arthropathies in animal studies
2) Cotrimoxazole in 1st & 3rd trimester
- Folate deficiency
- G6PD-Deficiency
- Kernicterus (Hyperbilirubinemia)
3) Nitrofurantoin at term
- G6PD Deficiency
4) Aminoglycosides used with caution
Antibiotics for UTI in pregnancy
- Beta-lactams
–> Cephalexin 500mg BD/
Augmentin 625mg TDS
Duration: 7days (Asymptomatic bacteruria/cystitis); 14 days (Pyelonephritis)
Choice based on culture
Adjunctive therapy for UTI
Pain & Fever: Paracetamol/NSAIDs
Vomiting: Rehydration
Urinary symptoms: Phenazopyridine 100-200mg TDS for duration of symptoms
Monitoring therapeutic response of UTI
- Should respond clinically within 2-3days; If persistently + blood/urine culture, further investigation needed:
- To exclude bacterial resistance/ possible obstruction/ Renal abscess/ Other disease process
- Repeat culture ONLY for pregnant women
- Absence of adverse drug reactions/allergies
