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pr3151 finals > IC13 Urinary Tract Infections > Flashcards

IC13 Urinary Tract Infections Flashcards

1
Q

What is the similarity and difference between asymptomatic bacteriuria (ASB) and urinary tract infection (UTI)?

A

Similarity: Isolation of significant colony counts of bacteria in the urine (bacteriuria) from a person

Difference: Symptoms
- ASB = No symptoms
- UTI = Symptoms (Invasion and inflammation)

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2
Q

What are the 3 categories of UTI?

A
  1. Upper UTI (Pyelonephritis - Kidneys)
  2. Lower UTI (Cystitis - Bladder; Urethritis; Prostatitis; Epididymitis)
  3. Catheter-associated UTI
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3
Q

Which 2 adult populations is screening and treatment of ASB is only indicated for? Why are they screened?

A
  1. Pregnancy - Prevent pyelonephritis, preterm labor and low birth weight of infant
  2. Urologic procedures where mucosal trauma or bleeding is expected (Not including urinary catheter placement) - Bacteria can enter the bloodstream, so you need to prevent postoperative bacteremia and sepsis
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4
Q

When are the 2 indicated adult populations screened for ASB?

A
  1. Pregnancy - One of the first visits (12-16 weeks gestation)
  2. Urologic procedure - Prior to procedure
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5
Q

If the 2 adult populations is screened and confirmed with ASB, what is the treatment?

A
  1. Pregnancy - Active Abx based on AST for 4-7 days
  2. Urologic procedure - Obtain culture then start active Abx as SAP based on culture & AST
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6
Q

Which 8 populations are never indicated for screening for ASB even though it is common in these patients? Why not screened?

A
  1. Children
  2. Healthy women (Premenopause, Postmenopause)
  3. Diabetes Mellitus
  4. Elderly in the community > 70 y.o.
  5. Elderly in Long-term care facility
  6. Spinal cord injury (Intermittent catheter use; Sphincterotomy/condom catheter)
  7. Kidney transplant patients
  8. Persons with indwelling catheter use (Long term urine catheter)

Reason: RCTs show that treatment does not decrease the risk of subsequent UTI in these patients.

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7
Q

Why is non-treatment of ASB important? When is treatment of ASB unwarranted and what should be done instead? When is it warranted?

A

To reduce the inappropriate use of abx

Having symptoms of delirium, falls, confusion and mental status changes ALONE without urinary symptoms DOES NOT indicate UTI. Other causes of delirium like dehydration should be evaluated.

Systemic infection with delirium may warrant empiric therapy

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8
Q

At what age is UTI more prevalent in one gender over another? Why?

A

0-6 mths - M > F (Structural functional abnormality)

1-adult - F > M (Shorter urethra)

Elderly (Age > 65) - Equal (Comorbidity causing obstruction or retention e.g. BPH, bowel incontinence due to stroke)

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9
Q

What are the 2 routes of UTI and how they cause UTI? (Pathogenesis)

A
  1. Ascending to bladder/kidney from gut bacteria
  2. Hematogenous (Descending) from distant primary site (Endocarditis, Osteomyelitis → Bacteremia in bloodstream → Urinary Tract)
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10
Q

What are the microorganisms causing UTI for the 2 different routes of infection?

A
  1. Ascending - Gut bacteria (E coli, Klebsiella, Proteus)
  2. Descending - S Aureus, M tuberculosis
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11
Q

What factors determine the development of UTI?

A
  1. Host Defense Mechanisms
  2. Inoculum Size (Increases with obstruction / urinary retention)
  3. Virulence / Pathogenicity (E.g. Bacteria with pili are resistant to micturition washout and bladder anti-adherence mechanism)
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12
Q

Explain the normal host defense mechanisms against UTIs.

A
  1. Bacteria in bladder stimulates micturition with increased diuresis → emptying of bladder
  2. Antibacterial properties of urine & prostatic secretion
  3. Anti-adherence mechanisms of bladder (prevent bacterial attachment to the bladder)
  4. Inflammatory response with polymorphonuclear leukocytes (PMNs) → phagocytosis → prevent/ control spread
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13
Q

What are the 11 risk factors for UTI and explain why they are risks?

A
  • Females > males - Shorter urethra
  • Sexual intercourse - Changes vaginal flora
  • Abnormalities of the urinary tract eg prostatic hypertrophy, kidney stones, urethral strictures, vesicoureteral reflux - Urinary obstruction
  • Neurological dysfunctions eg stroke, diabetes, spinal cord injuries - Urinary retention
  • Anticholinergic drugs - Urinary retention
  • Catheterization and other mechanical instrumentation - Harbor bacteria in biofilm
  • Diabetes - Sugar encourages bacteria growth
  • Pregnancy
  • Use of diaphragms & spermicides
  • Genetic association (positive family history, 1st degree female relatives)
  • Previous UTI
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14
Q

6 Non-pharmacological Prevention measures for UTI

A
  1. Hydration (6-8 glasses of fluid to flush bacteria)
  2. Frequent urination (Prevent bacteria growth)
  3. Urination after sex
  4. Wipe from front to back after bowel movement
  5. Keep area dry (Cotton underwear, loose-fitting clothing)
  6. Modify birth control method (Avoid diaphragm, spermicide, non-lubricated/spermicidal condoms)
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15
Q

2 Classifications of UTI and their 3 main differences (What clinical presentations? Who is at risks? What are the risks?)

A
  1. Complicated UTI
    - Mild cystitis to life-threatening urosepsis (Sepsis/Mortality)
    - In men, children, pregnant women
    - Complicating factors present: Functional / Structural abnormalities, Genitourinary instrumentations, DM patient, Immunocompromised
  2. Uncomplicated UTI
    - Mild Cystitis to severe pyelonephritis
    - Risks in healthy premenopausal, non-pregnant women (without history of abnormal urinary tract)
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16
Q

What are some differences in subjective symptoms for cystitis vs pyelonephritis

A
  1. Cystitis (LUTI) - Dysuria, urgency, frequency, nocturia, sprapubic heaviness / pain, gross hematuria
  2. Pyelonephritis (UUTI) - Fever, rigors, headache, nausea, vomiting, malaise, flank pain, costovertebral tenderness (renal punch), or abdominal pain
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17
Q

What are 2 objective diagnostics for UTI?

A
  1. Urinalysis (UFEME, Chemical analysis)
  2. Culture
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18
Q

What are the 3 methods of urine collection?

A
  1. Midstream clean-catch (After initial 20-30mL of urine disposed)
  2. Catheterization
  3. Suprapubic Bladder Aspiration using needle
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19
Q

What is UFEME? What results do you expect in microscopic urinalysis if there is UTI or not?

A

Urine Formed Elements and Microscopic Exam

  1. WBC > 10 cells/mm3 (Inflammation)
    - Presence may not indicate infection
    - Absence indicates it to be unlikely UTI
  2. RBC > 5/HPF or gross (Hematuria)
    - Non-specific (Menses, hemorrhage, catheter trauma)
  3. Microbes - Gram stain (Bacteria / Yeast)
  4. WBC casts - Renal tubular cell masses / proteins (Upper UTI)

UTI = Pyuria + Bacteriuria

Contamination - When there is high levels of squamous epithelial cells collected

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20
Q

When is chemical urinalysis (dipstick) done? What does it test for?

A

Primary care setting where there are no labs

  1. Nitrite positive = Gram negative bacteria (Only microbes that reduce nitrate to nitrite)
  2. Leukocyte esterase positive (Neutrophils in urine)
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21
Q

How much bacteria is required for nitrite test to be positive?

A

10^5 bacteria/mL

22
Q

When can a false negative nitrite test result occur?

A

Presence of Gram positives like P aeruginosa

Low urinary pH

Frequent voiding of urine

Diluted urine

23
Q

What should correlate with a positive LE test?

A

Significant pyuria > 10 WBCs/mm^3

24
Q

When is not necessary to obtain urine cultures?

A

Uncomplicated Cystitis

25
Q

When is it necessary to take pre-treatment cultures?

A
  • Pregnant women
  • Recurrent UTI (relapse within 2 weeks or frequent)
  • Pyelonephritis
  • Catheter-associated UTI
  • All men with UTI
26
Q

What are the likely pathogens for uncomplicated or community acquired UTI?

A

E coli (>85%)

Staphylococcus Saprophyticus (5-15%)

Other Gut Bacteria – Enterococcus faecalis, Klebsiella spp, Proteus mirabilis

27
Q

What are the likely pathogens for Complicated UTI / Healthcare-associated UTI?

A

E coli (About 50%)

Enterococci, Proteus, Klebsiella, Enterobacter, P aeruginosa

28
Q

What are health-care risk factors? What about these type of strains?

A

Recent and/or frequent exposure to healthcare settings:
1. Hospitalization in last 90 days
2. Current hospitalization > 2 days
3. Nursing homes
4. Recent antimicrobial use

May have more Abx-resistant strains

29
Q

What miscellaneous bacteria can be present and why?

A
  • S. aureus – commonly due to bacteremia; consider other primary site of infections
  • Yeast or Candida – possible contaminant; consider other sites of infection
30
Q

Selection of antibiotics for UTI depends on which 3 points?

A
  1. Need to treat? ASB vs UTI
  2. What is the organism factor? Community or nosocomial
  3. UTI type?
    * Cystitis in women
    * Community-acquired pyelonephritis in women
    * Community-acquired UTI in men
    * Nosocomial/ Healthcare-associated pyelonephritis
    * Catheter-associated UTI
    * UTI in pregnancy
31
Q

What are the 3 first line empiric antibiotics (with dosing regimen) used for Cystitis in Women?

A
  • PO cotrimoxazole 800/160 mg (2 tabs) bid x 3d
  • PO nitrofurantoin 50 mg (1 tab) qid x 5d
  • PO fosfomycin 3 g single dose sashay
32
Q

Why is fosfomycin used only for cystitis and when is it best used? Why do primary care still like to dispense it?

A
  • Does not reach kidney tissues (Pyelonephritis)
  • In hospitals against ESBL E coli (More resistant strains)
  • Easy to use (Sashay)
33
Q

What are alternative empiric antibiotics (with dosing regimen) used for Cystitis in Women?

A

1) Beta-lactams x 5-7 days
* PO cefuroxime 250 mg (1 tab) bid
* PO amoxicillin-clavulanate 625 mg (1 tab) bid
* PO cephalexin 250-500 mg (1-2 cap) qid

2) Fluoroquinolones x 3 days:
* PO ciprofloxacin 250 mg (Halved tab) bid
* PO levofloxacin 250 mg (Halved tab) daily

34
Q

What is the treatment duration for complicated cystitis in women?

A

7-14 days

35
Q

What is the fosfomycin dose for complicated cystitis?

A

PO 3 g EOD x 3 doses

36
Q

What are the empiric antibiotics (with dosing regimen) used for community acquired pyelonephritis in women?

A

1) Fluoroquinolones
* PO ciprofloxacin 500 mg twice daily x 7 days or
* PO levofloxacin 750 mg daily x 5 days or

2) Co-trimoxazole 160/800 mg twice daily x 10-14 days

3) PO Beta-lactam x 10-14 days
* PO cefuroxime 250-500 mg bid
* PO amoxicillin-clavulanate 625 mg tds
* PO cephalexin 500 mg qid

37
Q

For severely ill patients (women) with community acquired pyelonephritis who require hospitalization or NIL by mouth, take ___________________, then _______________

A

Empiric therapy:
IV ciprofloxacin 400 mg BID or
IV cefazolin 1 g q8h or
IV amoxi-clav 1.2g

switch to oral when patient improves or can take by mouth and change to culture-directed therapy

38
Q

What are the empiric antibiotics (with dosing regimen & duration) used for community acquired UTI in men?

A

Cystitis - Use as per Complicated cystitis in women (treat for longer duration - 7-14 days)

Cystitis with concern for prostatitis / Pyelonephritis:
- PO ciprofloxacin 500 mg twice daily or
- PO co-trimoxazole 160/800 mg twice-daily

For 10-14 days (Even longer if got prostatitis - 6 weeks)

39
Q

What are the empiric antibiotics (with dosing regimen & duration) used for nosocomial pyelonephritis?

A
  • IV cefepime 2g q12h +/- IV amikacin 15mg/kg/d or
  • IV imipenem 500mg q6h or IV meropenem 1g q8h
  • PO levofloxacin 750mg (for less sick patients)
  • PO ciprofloxacin 500mg bid (for less sick patients)
  • Duration of treatment is 7-14 days
40
Q

For nosocomial pyelonephritis, when is the usual onset?

A

> 48h post admission

41
Q

What are health-care associated risk factors for pyelonephritis?

A

Patients who have been hospitalized or underwent invasive urological procedures in the last 6 months, has an indwelling urine catheter

42
Q

Why are broad-spectrum Beta lactams considered for empiric therapy of nosocomial pyelonephritis?

A

The possibility of Pseudomonas aeruginosa and other resistant bacteria (eg extended beta-lactamase producing E coli and Klebsiella)

43
Q

What is the definition of catheter associated UTI?

A
  1. Presence of symptoms or signs compatible with UTI
  2. No other identified source of infection
  3. 10^3 cfu/mL of ≥1 bacterial species in a single catheter urine specimen
  4. In patients with indwelling urethral, indwelling suprapubic, or intermittent catheterization or in a midstream voided urine specimen from a patient whose catheter has been removed within the previous 48h
44
Q

What are the 6 risk factors for development of catheter associated UTI?

A
  • Duration of catheterisation
  • Colonisation of drainage bag, catheter and periurethral segment
  • DM
  • Female
  • Renal function impairment
  • Poor quality of catheter care, including insertion
45
Q

What are the causative organisms for short and long term catheterization?

A
  • Short-term catheterisation (<7 days) – 85% single organisms – reflecting that prevailing in environment
  • Long-term (>28 days) – 95% polymicrobial (2-3 organisms) especially if no new catheter put in
46
Q

What are the morbidity and mortality risks of catheter-associated UTI?

A
  • Symptomatic manifestation uncommon
  • Studies in long-term care facilities showed <10% febrile episodes due to UTI
  • Usually low-risk or not associated with excess mortality
47
Q

What should be done during treatment of catheter-associated UTI?

A
  • Removal of catheter should always be considered
  • If an indwelling catheter has been in place for > 2 weeks at the onset of CA-UTI and is still indicated, the catheter should be replaced to hasten resolution of symptoms and to reduce the risk of subsequent CA- bacteriuria and CA-UTI.
48
Q

What kind of symptoms for catheter-associated UTI warrants antibiotics? When should observation be considered?

A
  1. New onset or worsening of fever, rigors
  2. Altered mental status, malaise, or lethargy with no other identified cause;
  3. Flank pain; costovertebral angle tenderness; acute hematuria; pelvic discomfort.

If patient is stable and fever is low grade, consider observation rather than immediate antibiotics therapy

49
Q

What are the empiric antibiotics (with dosing regimen & duration) used for CAUTI?

A
  • IV imipenem 500mg q6H or IV meropenem 1g q8h
  • IV cefepime 2g q12H +/- IV amikacin 15mg/kg (1 dose)
  • PO/ IV levofloxacin 750mg x 5d (for mild CA-UTI)
  • PO Co-trimoxazole 960mg bid x 3d (for women ≤65 years with CA-UTI without upper urinary symptoms after an indwelling catheter has been removed)
50
Q

How to prevent catheter associated UTI? (8 prevention measures)

A
  • Avoid unnecessary catheter use
  • Use for minimal duration
  • Long-term indwelling catheters changed before blockage is likely to occur
  • Use of closed system
  • Ensure aseptic insertion technique
  • Topical antiseptic or antibiotics not recommended
  • Prophylactic antibiotics and antiseptic not recommended
  • Chronic suppressive antibiotics is not recommended.
51
Q

What antibiotics should be avoided at what term of pregnancy and why?

A
  1. Ciprofloxacin - Fetal cartilage damage & arthropathy
  2. Cotrimoxazole (1st & 3rd trimester) - Folate deficiency, Kernicterus, G6PD deficiency
  3. Nitrofurantoin (38-42 weeks) - G6PD deficiency
  4. Aminoglycosides (Caution) - 8th cranial nerve toxicity in the fetus
52
Q

Treatment durations for ASB and pyelonephritis in pregnant women

A

4-7 days for ASB and 14 days for pyelonephritis

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