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MBBS 3: Internal Medicine > Urinary Tract Infections > Flashcards

Urinary Tract Infections Flashcards

1
Q

Classification of UTIs?

A
  1. Asymptomatic bacteriuria
  2. Symptomatic lower UTI
    e.g. Acute cystitis
  3. Upper UTI
    e.g. Acute pyelonephritis
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2
Q

Epidemiology of UTI?

A

UTI is more common in females.
- (1-2% of young non-pregnant women)
- 40% of females will have a symptomatic UTI in their life time.

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3
Q

UTI in men?

A

prevalence is 0.04%

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4
Q

Incidence of UTIs?

A
  • Incidence of UTI increases in old age
  • 10% of men & 20% of women
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5
Q

Routes of infection?

A
  1. ascending infection
  2. hematogenous spread
  3. lymphogenous spread
  4. direct extension from other organs
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6
Q

Most common route of infection in UTIs?

A

Ascending infection from the urethra is the most common route
Note: Pyelonephritis most commonly results from ascent of infection up the ureter.

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7
Q

Hematogenous cause of UTIs?

A

hematogenous spread to the urinary tract is uncommon, the exceptions being:
1. tuberculosis
2. cortical renal abscesses

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8
Q

Lymphogenous spread?

A

is rare

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9
Q

Direct extension from other organs?

A

Direct extension from other organs may occur, especially from
1. intra-peritoneal abscesses in inflammatory bowel disease
2. pelvic inflammatory disease

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10
Q

Risk factors for UTIs in females?

A
  1. sexual activity
    - use of spermicidal, diaphragm
  2. Pregnancy.
  3. Estrogen deficiency (Post menopausal )
  4. short urethra
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11
Q

Risk factors for UTIs in males?

A
  1. lack of circumcision,
  2. prostatic hypertrophy,
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12
Q

Risk factors for UTIs in both sexes?

A
  1. Obstruction,
  2. Vesicoureteric reflux,
  3. Instrumentation, & catheterization
  4. Neurogenic disorders that impairs bladder, emptying
  5. Diabetes (increase risk of complications and fungal infections)
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13
Q

How is obstruction a risk factor for UTIs?

A

any microorganism that enter the bladder is washed out during voiding therefore when outflow is obstructed urine remains in bladder — medium for microbial growth

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14
Q

How is increased pressure in the bladder a risk factor for UTIs?

A

Increase pressure in bladder compresses vessels in bladder wall
- decrease in the mucosal defense

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15
Q

Anatomical obstructions that are risk factors for UTIs?

A
  1. Stones
  2. Prostatic hyperplasia
  3. Pregnancy
  4. Malformation of ureterovesical junction
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16
Q

Functional obstructions that are risk factors for UTIs?

A
  1. Neurogenic bladder
  2. Infrequent voiding
  3. Constipation
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17
Q

How are catheter induced infections risk factors for UTIs?

A
  1. Provide a means for entry of microorganisms into the urinary tract
  2. Bacteria adhere to surface of catheter & initiate the growth of biofilm that covers the surface of catheter.
  3. Biofilm protects the bacteria from antibiotics
18
Q

Causes of uncomplicated lower UTIs?

A
  1. Escherichia Coli - gram negative bacillus
  2. Staphylococcus saprophyticus - gram positive coccus
19
Q

Causes of complicated UTIs?

A
  1. Proteas mirabiris
  2. Klebsiella species
  3. Enterobacter species
  4. Pseudomonas Eurogenosa
    - mainly gram negative rods
  5. Staph aurius (gram positive cocci)
20
Q

What is the pathogenesis of UTIs?

A

Pathogenesis of UTI involves interaction of host with agent leading to let down of host defences against virulence of infectious agents

21
Q

Components of the bladder that act as host defences in preventing UTIs?

A

Urinary bladder is usually resistant to bacterial colonization
1. Washout Phenomenon
- Bacteria removed during voiding
2. Protective mucin layer
- Protects against bacterial invasion
3. Immune mechanisms
- secretory immunoglobulin(lgA), PMN cells

22
Q

What other urinary host defences prevent UTIs?

A
  1. Normal flora in periurethral area in women
  2. prostatic secretions in males
23
Q

What kind of E.coli produces UTI?

A

Only those strains of E-coli with increased ability to adhere to epithelial cells to produce UTI
- Most E.coli causing UTI belong to O,K and H serotypes.

24
Q

Describe the pathogen virulence that allows E. coli to produce UTIs?

A

Uropathogenic E.coli have
1. fimbria /Pilli - for adherence
2. Secrete hemolysin & aerobactin -resist serum bactericidal action

25
Q

Pathogenesis of Uropathogenic E.coli?

A
  1. Periuretheral area & urethra are colonised by bacteria.
  2. Bacteria enter bladder in susceptible host.
  3. Adherence properties enable pathogens to colonise bladder
  4. Pathogens attach to uroepithelial mucosa, secretion of cytokines recruitment of PMNs inflammation.
  5. Pathogens may ascend through ureter to kidney causing pyelonephritis
26
Q

Clinical presentations of UTIs?

A
  1. asymptomatic bacteriuria
  2. cystitis
  3. acute pyelonephritis
27
Q

Features of asymptomatic bacteriuria?

A
  1. Common in females & elderly.
  2. 25% develop symptomatic UTI
  3. 25% clear spontaneously.
  4. Spontaneous cure & reinfection are common
28
Q

Features of cystitis?

A
  1. Frequency, dysuria , urgency.
  2. Suprapubic discomfort +/- tenderness.
  3. Fever is often absent
  4. Ocasionally urine is cloudy and foul smelling
29
Q

Features of acute pyelonephritis?

A
  1. Fever, abdominal pain, vomiting.
  2. Dysuria ,frequency, flank or loin pain.
  3. Flank or loin tenderness.
  4. In elderly: symptoms are often atypical.
  5. Bacteremia is common.
30
Q

Describe the change in renal anatomy and physiology of pregnant women?

A
  1. Dilation of calyces, pelvis and ureters.
  2. Reduction in peristaltic activity of ureters
    - thought to be muscle relaxing effect of progesterone
    - mechanical obstruction from enlarge uterus
31
Q

Complications of UTI in pregnant women?

A
  1. Persistent bacteriurea
    - UTI during pregnancy may be the result of preexisting asymptomatic bacteuria therefore Urine culture is recommended at first prenatal visit
  2. Acute or chronic pyelonephritis
  3. premature delivery.
  4. low birth weight infant.
  5. Increased newborn mortality
32
Q

Describe UTIs in the elderly?

A
  • Second most common cause of infection after respiratory tract infection
  • Vague symptoms –anorexia,fatigue and weakness
  • Difficult to interpret because elderly people without UTI also commonly experience urgency, frequency and incontinence.
33
Q

Investigations and making a diagnosis of UTIs?

A
  1. Urine microscopy: -WBCs, RBCs
  2. Urine dipstick
    - Nitrites,Leukocytes
  3. more markers of infection
  4. Urine culture & sensitivity to antibiotics
  5. Significant bacteriuria= 100000 cfu/ml
  6. symptoms: 1 +ve culture = infection
34
Q

Diagnosing UTIs?

A
  1. Symptoms: 10000 cfu/ml = propable infection
  2. Asymptomatic: 2 +ve urine cultures = infection
  3. False negative : antibiotics, antiseptics, diuresis.
  4. FBC
  5. BLOOD CULTURE
35
Q

What kind of sample is needed to test for UTIs?

A

to confirm diagnosis always send a mid-stream urine sample for culture, collected before antibiotics

36
Q

Urine dipstick test results that correspond to UTIs?

A

Positive dipstick
a urine dipstick test with positive nitrites makes UTI more likely in men (PPV 96%)
Negative dipstick
Negative for both nitrite and leucocyte makes UTI less likely, especially if symptoms are mild

37
Q

Investigations used to identify contributing factors like obstruction?

A
  1. X-ray
  2. Ultrasonography
  3. CT scan
  4. Renal scans
38
Q

Management of lower UTI in non-pregnant women?

A

dependent on local guidelines
1. Trimethoprim
2. Nitrofurantoin
3. quinolones

39
Q

Management of lower UTI in pregnant women?

A
  1. send urine culture
  2. Nitrofurantoin
    - avoid near term of pregnancy
  3. Amoxicillin or cefalexin for second line
    - Avoid Trimethoprim and quinolones because they are teratogenic
  4. Treat asymptomatic bacteriuria in pregnancy
    - do urine cultures routinely
40
Q

UTI management in men?

A

Immediate abx therapy for 7 days
1. Start with Trimethoprim (dependent on local sensitivities) or Nitrofurantoin
2. Quinolones
3. Do not treat asymptomatic bacteriuria in catheterised patients

41
Q

Upper UTI treatment for acute pyelonephritis?

A
  1. Broad-spectrum antibiotics, cephalosporins or quinolones.
  2. Manage any complications like Urosepsis accordingly
  3. Refer to urology for suspected recurrent UTIs for suspected urinary tract abnormality corrections

MBBS 3: Internal Medicine (72 decks)

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