Urinary Tract Infections Flashcards

1
Q

How is the urinary tract protected from infection?

A

A variety of defence mechanisms

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2
Q

What is the most important defence mechanism in protection of the urinary tract?

A

Regular flushing during voiding

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3
Q

What does flushing during voiding do?

A

Removes organisms from the distal urethra

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4
Q

What happens between voiding?

A

Organisms may ascend the urethra

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5
Q

What is the result of organisms ascending the urethra between voiding?

A

Infection is commoner in females, because the urethra is comparitavely short

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6
Q

What are the host factors in the pathogenesis of urinary disease?

A
  • Shorter urethra
  • Obstruction
  • Neurological
  • Ureteric reflux
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7
Q

What may a shorter urethra lead to?

A

More infections in females

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8
Q

What may cause urethral obstructions?

A
  • Enlarged prostate
  • Pregnancy
  • Stones
  • Tumours
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9
Q

What can neurological urinary disease cause?

A
  • Incomplete emptying
  • Residual urine
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10
Q

What can ureteric reflux cause?

A

Ascending infection from bladder, especially in children

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11
Q

What are the bacterial factors in the pathogenesis of urinary disease?

A
  • Faecal flora
  • Adhesion
  • K Antigens
  • Haemolysins
  • Urease
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12
Q

What are faecal flora?

A

Potential urinary pathogens that colonise the periurethral area

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13
Q

What is required for bacterial adhesion?

A

Fimbriae and adhesins

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14
Q

What do fimbriae and adhesins allow in urinary infections?

A

Attachment to the urethral and bladder epithelium

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15
Q

What do K antigens do?

A

Allow some E. coli to resist host defences by producing polysaccharide capsule

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16
Q

What do haemolysins do?

A

Damage membranes and cause renal damage

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17
Q

What produces urease?

A

Some bacteria, e.g. proteus

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18
Q

What does urease do?

A

Breaks down urea for energy

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19
Q

How severe are most UTIs?

A

Most are mild

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20
Q

What may renal infections lead to?

A

Long term renal damage

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21
Q

What is the urinary tract a common source of?

A

Life threatening Gram -ve bacteraemia

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22
Q

What is the most common UTI?

A

Cystitis

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23
Q

Where does cystitis affect?

A

The lower tract

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24
Q

What may an upper UTI result from?

A

Haematogenous or ascending routes of infection

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25
Q

What are the types of lower UTI?

A
  • Bacterial cystitis
  • Abacterial cystitis
  • Prostatitis
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26
Q

What does bacterial cystitis cause?

A

Frequency and dysuria, often with pyuria and haematuria

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27
Q

What does abacterial cystitis cause?

A

The same as bacterial, but without significant bacteriruia

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28
Q

What does prostatitis cause?

A
  • Fever
  • Dysuria
  • Increased frequency
  • Perineal and low back pain
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29
Q

What are the types of upper UTIs?

A
  • Acute pyelonephritis
  • Chronic interstitial nephritis
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30
Q

What does acute pyelonephritis cause?

A

The symptoms of cystitis plus fever and loin pain

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31
Q

What does chronic interstitial nephritis cause?

A

Renal impairment following chronic inflammation

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32
Q

What can cause asymptomatic UTIs?

A

Covert bacteriuria

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33
Q

How can covert bacteria causing UTIs be detected?

A

Only in culture

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34
Q

When is covert bacteria causing UTIs important?

A

In children and pregnancy

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35
Q

What are the most common pathogens in the community?

A

Gram -ve rods, particularly the enterobacteriaceae

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36
Q

What % of bacteria in the community are gram -ve rods?

A

80%

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37
Q

What are enterobactericeae known as?

A

Coliforms

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38
Q

What type of coliform is particularly common in the community?

A

E. Coli

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39
Q

Who may develop a UTI due to coagulase-negative staphylococci?

A
  • Young women
  • Hospitalised patients
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40
Q

Give an example of a coagulase-negative staphylococci

A

Staph. Saprophyticus

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41
Q

Why are young women and hospitalised patients at a higher risk of developing a UTI due to coagulase negative staphylococci?

A

Due to increased risk factors, e.g. catherisation

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42
Q

Why does cathertisation increase the risk of UTIs?

A

Biofilms

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43
Q

Who do uncomplicated UTIs develop in?

A

Healthy women

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44
Q

Who do complicated UTIs develop in?

A
  • Pregnancy
  • Treatment failure
  • Suspected pyelonophritis
  • Complications
  • Males
  • Paediatrics
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45
Q

Does urine need to be cultured in uncomplicated UTIs?

A

No

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46
Q

Why is there no need to culture urine in uncomplicated UTIs?

A

Infection is indicated by nitrite/leukocyte esterase dipstick testing

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47
Q

How can samples be collected in complicated UTIs?

A
  • Mid-stream specimen
  • Catheter samples
  • Supra-pubic aspiration
  • Adhesive bags
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48
Q

Why is a mid-stream sample collected when investigating complicated UTIs?

A

As we do not want to culture the urethras normal flora, so allow for a small amount of urine to be passed to ‘clear’ it before collecting the sample

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49
Q

When may an adhesive bag be used to collect a urine sample

A

In small children, who it is difficult to get samples in

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50
Q

What is the false positive rate of collecting a urine sample by placing an adhesive bag over genitals?

A

20%

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51
Q

Where is a catheter sample taken from?

A

Not from the bag, but by using a needle up a special tube in the catheter

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52
Q

What happens in supra-pubic aspiration?

A

A sample of bladder urine is obtained by using a needle through the abdominal wall

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53
Q

How commonly is supra-pubic aspiration used?

A

Rarely

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54
Q

Under what conditions do urine samples need to be transported?

A
  • Kept at 4oC
  • Small amount of boric acid in the collection tube
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55
Q

What is the purpose of the conditions that urine samples are kept under once collected?

A

It stops bacterial division to keep the sample representative of the collection time

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56
Q

What investigations are undertaken on urine samples?

A
  • Turbidity
  • Dipstick testing
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57
Q

What is meant by investigating turbidity?

A

Look to see if the sample is cloudy

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58
Q

What is cloudy urine indicative of?

A

A UTI

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59
Q

What is being looked for during dipstick testing?

A
  • Leukocyte esterase
  • Nitrite
  • Haematuria
  • Proteinuria
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60
Q

What does leukocyte esterase in urine indicate?

A

Presence of WBCs

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61
Q

What does nitrite indicate in urine?

A

The presence of Nitrate reducing bacteria

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62
Q

Can haematuria and proteinuria be used to diagnose a UTI?

A

No, because there are many causes of these symptoms

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63
Q

When is microscopy used to investigate UTIs?

A
  • Kidney disease
  • Suspected endocarditis
  • Children under 6
  • Schistosomiasis
  • Suprapubic aspirates
  • When requested
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64
Q

What may indiciate kidney disease in UTIs?

A
  • Lion pain
  • Nephritis
  • Hypertension
  • Toxaemia
  • Renal colic
  • Haematuria
  • Renal TB
  • Casts
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65
Q

What distinguishes between bacteriuria/contamination in a urine culture?

A

A number of colony forming units > 100,000per ml (105 cfu/ml)

66
Q

What % predictive is a single urine specimen?

A

80%

67
Q

When is a urine culture used?

A

To investigate complicated UTIs

68
Q

Why is a urine culture preferential to a urine sample?

A

Increased sensitivity (down to 102 cfu/ml)

69
Q

What can a urine culture be used to determine?

A
  • Epidemiology of isolates
  • Sensitivity
  • Specimen quality
70
Q

How can a urine culture be used to control specimen quality?

A

Can differentiate between properly collected and contaminated samples

71
Q

How can a urine culture be used to differentiate between properly collected and contaminated samples?

A

Poorly collected samples may contain epithelial cells

72
Q

How is a urine culture report interpreted?

A
  • Clinical details
  • Quality of specimen
  • Delays in culture
  • Microscopy (if available)
  • Organism(s) located
73
Q

What clinical details should be considered when interpreting a culture report?

A
  • Symptoms
  • Previous antibiotics
74
Q

What is sterile pyuria?

A

Pus in urine

75
Q

What happens in sterile pyuria?

A

A UTI is present, but unable to be cultured

76
Q

Why may sterile pyuria occur?

A
  • The patient may have aleady been treated with antibiotics
  • Infected with bacteria that are difficult to isolate or culture
  • Tuberculosis
  • Appendicitis
77
Q

Give an example of a bacteria that is difficult to isolate or culture?

A

Chlamydia

78
Q

Why may appendicitis cause sterile pyuria?

A

The appendix is stuck on the bladder

79
Q

Do all adult women who present with classic UTI symptoms have a UTI?

A

No

80
Q

How are adult women who present with classic UTI symptoms treated?

A

As though they have one, until proved otherwise

81
Q

What may cause classic UTI symptoms that is not a UTI?

A
  • Significant bacteriuria
  • Urethral syndrome
82
Q

What may cause urethral syndrome?

A
  • Low-count bacteriuria
  • Fastidious organisms
  • Vaginal infection/inflammation
  • Sexually transmitted pathogens
  • Mechanical, physical, and chemical causes
83
Q

What may sexually transmitted pathogens cause?

A

Urethritis

84
Q

What are the general principles of UTI treatment?

A
  • Increase fluid intake
  • Address underlying disorder
85
Q

What is done when bacteria are present asymptomatically in UTIs?

A

Only treat once symptoms appear

86
Q

How is an uncomplicated UTI treated?

A

3 day course of antibiotics

87
Q

Why is an uncomplicated UTI treated with a 3 day course of antibiotics?

A

3 days reduces the selection pressure for resistance

88
Q

How is a complicated UTI treated?

A

7 day course of antibiotics

89
Q

What antibiotic is not appropriate for treatment of a complicated UTI?

A

Amoxicillin

90
Q

Why is amoxicillin not appropriate in the treatment of a complicated UTI?

A

50% of isolates are resistant

91
Q

How is pyelonephritis/septicaemia treated?

A

14 day course of antibiotics

92
Q

What is used in the treatment of pyelonephritis/septicaemia?

A

A more potent agent with systemic activity

93
Q

When is prophylaxis used in the treatment of UTIs?

A

When there are 3 or more episodes in one year with no treatable underlying condition

94
Q

What is given in UTI prophylaxis?

A

Single, low, nightly dose of antibiotics

95
Q

What is the purpose of the antibiotics given in UTI prophylaxis?

A

To prevent bacteria build up in static urine

96
Q

What must be done in UTI prophylaxis?

A

All breakthrough infections documented

97
Q

What do diuretics do?

A

Block the reabsorption of Na+ and therefore water by the kidney

98
Q

What are the types of diuretics?

A
  • Loop
  • Thiazide
  • K+ Sparing
  • Aldosterone Antagonists
99
Q

What kind of diuretic is most powerful?

A

Loop

100
Q

What are loop diuretics capable of?

A

Causing the excretion of 10-25% of filtered Na+ ions

101
Q

How do loop diuretics work?

A

By blocking the Na-2Cl Symporter in the apical membrane

102
Q

Give two examples of loop diuretics

A
  • Furosemide
  • Bumetanide
103
Q

Draw a diagram illustrating the function of loop diuretics

A
104
Q

Where do thiazide diuretics act?

A

On the early DCT

105
Q

What are thiazide diuretics capable of?

A

Inhibiting only 5% of Na+ reabsorption, less potent than loop diuretics

106
Q

Where are thiazide diuretics ineffective?

A

In the treatment of renal failure

107
Q

How do thiazide diuretics work?

A

By blocking the Na-Cl Symporter

108
Q

Give an example of a thiazide diuretic

A

Bendroflumethiazide

109
Q

Draw a diagram illustrating the action of thiazide diuretics

A
110
Q

Where do K+ sparing diuretics and aldosterone antagonists act?

A

On the late DCT

111
Q

What do K+ sparing diuretics and aldosterone antagonists act to do?

A

Reduce Na+ channel activity

112
Q

What are K+ sparing diuretics and aldosterone antagonists capable of doing?

A

Both mild diuretics, inhibiting only 2% of Na+ reabsorption

113
Q

What effect do K+ sparing diuretics and aldosterone antagonists have on K+?

A

They reduce the loss of K+

114
Q

What is a potential problem with K+ sparing diuretics and aldosterone antagonists?

A

They can both produce life threatening hyperkalaemia

115
Q

When may K+ sparing diuretics and aldosterone antagonist cause life threatening hyperkalaemia?

A

In renal failure

116
Q

Give an example of a K+ sparing diuretic

A

Amiloride

117
Q

Give an example of an aldosterone antagonist

A

Spironolactone

118
Q

Draw a diagram illustrating the action of K+ sparing diuretics and aldosterone antagonists

A
119
Q

What are the potential adverse effects of diuretic use and abuse?

A
  • Effects on potassium
  • Hypovolaemia
  • Hyponatraemia
  • Increase uric acid levels in the blood
  • Metabolic effects
  • Carbonic anhydrase inhibition
120
Q

What kind of diaretics may cause hypokalaemia?

A

Loop and thiazide

121
Q

Why may loop and thiazide diuretics cause hyperkalaemia?

A

Because they reduce the loss of potassium in urine

122
Q

Is hypo or hyperkalaemia life threatening?

A

Either can be

123
Q

What is the result of diuretics reducing ECF volume?

A

They cause the activation of RAAS

124
Q

What is the effect of diuretics causing the activation of RAAS?

A

It will cause aldosterone secretion, increasing Na+ absorption and K+ secretion, helping contribute to hypokalaemia

125
Q

Draw a diagram illustrating the potential adverse effects of diuretics

A
126
Q

What is hypovolaemia?

A

Decreased ECF volume

127
Q

What is hypovolaemia due to?

A

Excessive loss of Na+ and water

128
Q

What should be monitered in the case of hypovolaemia?

A
  • Weight
  • Signs of dehydration
  • BP
129
Q

How can BP be monitered in hypovolaemia?

A

Look for postural hypertension

130
Q

What can increased uric acid levels in the blood do?

A

Precipitate attack of Gout

131
Q

What are the potential metabolic effects of diuretics?

A
  • Glucose intolerance
  • Increased LDL levels
132
Q

What diuretics inhibit carbonic anhydrase?

A

Those that act in the PCT by inhibiting the enzyme carbonic anhydrase

133
Q

What is the effect of carbonic anhydrase inhibition?

A

It interferes with Na+ and HCO3- reabsorption

134
Q

Why are carbonic anhydrase inhibitors no longer used as a diuretic?

A

As HCO3- loss leads to metabolic acidosis

135
Q

What are diuretics used to treat?

A
  • Conditions with ECF expansion and oedema
  • Acute pulmonary oedema
  • Hypertension
136
Q

What conditions have ECF expansion and oedema?

A
  • Congestive heart failure
  • Nephrotic syndrome
  • Kidney failure
  • Ascites and oedema due to cirrhosis of the liver
  • Hypercalcaemia
  • Cerebral oedema
  • Glaucoma
137
Q

What diuretic is used to treat kidney failure?

A

Loop

138
Q

What diuretic is used to treat ascites and odema due to cirrhosis or the liver?

A

Spironolactone

139
Q

What is used to treat acute pulmonary oedema?

A

IV Furosemide

140
Q

What causes acute pulmonary oedema?

A

Left heart failure

141
Q

How is is hypertension treated?

A

Thiazide diuretics or spironolactone

142
Q

When is spironolactone used to treat hypertension?

A

In primary hyperaldosteronism (Conn’s syndrome)

143
Q

What diuretics are used to treat hypercalcaemia?

A

Loop

144
Q

Why are loop diuretics used to treat hypercalcaemia?

A

They promote calcium excretion by the Loop of Henle

145
Q

What diuretics are used in the treatment of cerebral oedema?

A

Osmotic diuretics

146
Q

Give an example of an osmotic diuretic

A

Mannitol

147
Q

What diuretic is used in the treatment of glaucoma?

A

Acetazolamide

148
Q

What kind of diuretic is acetazolamide?

A

Carbonic anhydrase

149
Q

What substances have diuretic action?

A
  • Alcohol
  • Coffee
  • Other drugs
150
Q

How does alcohol have a diuretic action?

A

It inhibits ADH release

151
Q

How does coffee have a diuretic action?

A

It increases GFR and decreases tubular Na+ reabsorption

152
Q

What drugs have a secondary diuretic action?

A
  • Lithium
  • Demeclocycline
153
Q

How do lithium and democlocycline have a diuretic action?

A

They inhibit ADH action on collecting ducts

154
Q

What is the symptom of diseases causing diuresis?

A

Polyuria

155
Q

What is polyuria?

A

More than 2.5L urine/day

156
Q

What diseases cause diuresis?

A
  • Diabetes mellitus
  • Diabetes insipidus (cranial)
  • Diabetes insipidus (nephrogenic)
  • Psychogenic polydipsia
157
Q

How does diabetes mellitus cause diuresis?

A

Glucose in filtrate leads to osmotic diuresis

158
Q

How does cranial diabetes insipidus cause diuresis?

A

Decreased ADH release from posterior pituitary leads to diuresis

159
Q

How does nephrogenic diabetes insipidus cause diuresis?

A

Poor response of collecting ducts to ADH leading to diuresis

160
Q

What is psychogenic polydipsia?

A

Increased intake of fluid