Urinary Tract Infection

Question 1

Urinary tract infections (UTIs) refer to an infection of any part of the urinary system from .. to the ..

Answer 1

Urinary tract infections (UTIs) refer to an infection of any part of the urinary system from kidney to the urethra.

Question 2

UTIs are generally defined as the presence of characteristic symptoms (e.g. dysuria, frequency) and significant bacteriuria (presence of bacteria in urine). Significant bacteriuria is defined as > … colony forming units (CFU)/ml. In the absence of symptoms, this level of bacteriuria is termed asymptomatic bacteriuria.

Answer 2

UTIs are generally defined as the presence of characteristic symptoms (e.g. dysuria, frequency) and significant bacteriuria (presence of bacteria in urine). Significant bacteriuria is defined as > 10^5 colony forming units (CFU)/ml. In the absence of symptoms, this level of bacteriuria is termed asymptomatic bacteriuria.

Question 3

UTIs can be further categorised depending on the location of infection (e.g. upper or lower) or the presence of co-morbidities (e.g. complicated or uncomplicated).

Answer 3

Upper UTI: infection of the kidney (pyelonephritis)

Lower UTI: infection of the bladder (cystitis) and urethra (urethritis)

Uncomplicated UTI: if occurring in healthy non-pregnant adult women

Complicated UTI: the presence of factors that increase the risk of treatment failure (e.g diabetes, structural abnormalities, catheter and other devices and all UTIs in men)

Question 4

UTIs occurring in men are generally considered ‘…’ as many occur in children and the elderly in association with urological abnormalities, malignancy or immunosuppression.

Answer 4

UTIs occurring in men are generally considered ‘complicated’ as many occur in children and the elderly in association with urological abnormalities, malignancy or immunosuppression.

Question 5

UTIs are caused by the organism… in 75-90% of cases.

Answer 5

UTIs are caused by the organism Escherichia coli in 75-90% of cases.
Gram negative bacillus

Question 6

Escherichia coli (E. coli) is a … bacillus that is a facultative inhabitant of the large intestines. E. coli may cause a wide range of infections including, respiratory infections, intra-abdominal infections, enteric infections and urinary infections.

Uropathogenic strains of E. coli infect the urinary tract leading to a wide range of problems including urethritis, prostatitis, cystitis, pyelonephritis and urosepsis.

Answer 6

Escherichia coli (E. coli) is a gram-negative bacillus that is a facultative inhabitant of the large intestines. E. coli may cause a wide range of infections including, respiratory infections, intra-abdominal infections, enteric infections and urinary infections.

Uropathogenic strains of E. coli infect the urinary tract leading to a wide range of problems including urethritis, prostatitis, cystitis, pyelonephritis and urosepsis.

Question 7

Other common microorganisms associated with UTIs include: (aside from E.coli)

Answer 7

Proteus mirabilis
Klebsiella pneumoniae
Staphylococcus saprophyticus

Question 8

A growing number of UTIs are secondary to … (ESBL) producing E. coli.

Answer 8

A growing number of UTIs are secondary to extended-spectrum beta-lactamase (ESBL) producing E. coli.

Question 9

ESBL
A growing number of UTIs are secondary to extended-spectrum beta-lactamase (ESBL) producing E. coli.

What are they highly resistant to?

Answer 9

These organisms are highly resistant to most beta-lactam antibiotics, which includes penicillins and cephalosporins. Beta-lactamases are enzymes which open the beta-lactam ring of beta-lactam antibiotics rendering them inactive.

Question 10

ESBL infections are a growing cause of hospital-acquired infections associated with poor outcomes. The risk of developing ESBL infections is linked to the prior administration of antibiotics, the length of ITU stay and the presence of a urinary catheter, among others. Treatment often requires …

Answer 10

ESBL infections are a growing cause of hospital-acquired infections associated with poor outcomes. The risk of developing ESBL infections is linked to the prior administration of antibiotics, the length of ITU stay and the presence of a urinary catheter, among others. Treatment often requires potent, broad-spectrum antibiotics (e.g. Carbapenems).

Question 11

Pathophysiology of UTI - overview

Answer 11

The normal urinary tract is a sterile environment.
The development of UTIs results from colonisation and ascending spread of microorganisms from the urethra into the bladder (lower) and kidney (upper), or by haematogenous spread via the blood. Many pathogens have adaptions that allow them to breach host defences.

Question 12

Microorganism spread - UTI

Answer 12

In women, infections start with the colonisation of the vaginal introitus (entrance to the vaginal canal) and periurethral area. It then ascends the urethra to cause infection of the bladder. Infections are uncommon in men for a number of reasons. They have a longer urethra, prostatic secretions have some antimicrobial properties and their periurethral area is generally drier.

Question 13

Why are UTIs less common in men?

Answer 13

Infections are uncommon in men for a number of reasons. They have a longer urethra, prostatic secretions have some antimicrobial properties and their periurethral area is generally drier.

Question 14

UTIs may also develop from the haematogenous spread of microorganisms. However, common gram-negative bacilli (e.g. E. coli) are unlikely to cause infection by this route. Haematogenous spread is more often seen with uncommon urinary microorganisms such as …

Answer 14

UTIs may also develop from the haematogenous spread of microorganisms. However, common gram-negative bacilli (e.g. E. coli) are unlikely to cause infection by this route. Haematogenous spread is more often seen with uncommon urinary microorganisms such as Staphylococcus aureus, Candida albicans and Mycobacterium tuberculosis.

Question 15

Host and pathogen - UTI

Answer 15

The ability of microorganisms to infect the urinary system is dependent on both the host and pathogen. Host factors such as intercurrent illness, immunosuppression (e.g. steroid use) or co-morbidities (e.g. diabetes) can increase the risk of developing a UTI.

Some pathogens are particularly well suited to infecting the urinary tract. For example, uropathogenic strains of E. coli contain fimbriae, these are hair-like protein polymers that project from the bacterial surface. They allow strong adherence to the urothelium. Fimbriae play a crucial role in the pathogenesis of UTIs and have been shown to increase bacterial survival.

Question 16

Risk factors for UTI

Answer 16

UTIs are extremely common especially among young, sexually active females.

Risk factors for the development of UTIs include:

Recent sexual intercourse
Diabetes
History of UTIs
Spermicide use
Catheters

Question 17

… are one of the major risk factors for developing a UTI in secondary care.

Answer 17

Urinary catheters are one of the major risk factors for developing a UTI in secondary care. UTIs associated with catheters are a leading cause of hospital-associated bacteraemia.

Question 18

Typical clinical features of UTIs include (2)

Answer 18

Typical clinical features of UTIs include dysuria (often described as burning) and increased frequency.

Question 19

Symptoms in UTI

Answer 19

Dysuria
Frequency
Urgency
Incontinence
Suprapubic pain
Haematuria
N&V

Question 20

Dysuria is commonly described, women who suffer with recurrent UTIs will often identify the symptoms early. Clinicians should be alert for signs of … which include kidney pain, myalgia, fevers, rigors and nausea/vomiting.

Answer 20

Dysuria is commonly described, women who suffer with recurrent UTIs will often identify the symptoms early. Clinicians should be alert for signs of pyelonephritis which include kidney pain, myalgia, fevers, rigors and nausea/vomiting.

Question 21

Signs of UTI

Answer 21

Fever
Rigors
Flank pain
Confusion
Costovertebral angle tenderness

Question 22

Signs and symptoms of…

Answer 22

UTI

Question 23

Urosepsis - define

Answer 23

Urosepsis refers to a sepsis that originates from a urinary infection. Sepsis can be thought of as a dysregulated host response to infection leading to life-threatening organ dysfunction. Features include haemodynamic instability, tachypnea, changes to mental status, reduced urine ouput and pyrexia.

Question 24

There are a number of scoring systems that can be used to assess risk and prognosis, each has their own limitations. An example is qSOFA (quick Sepsis Related Failure Assessment) that aims to identify patients at increased risk of poor outcomes outside the ITU environment. It consists of three components:

Answer 24

Mental status (score 1 if altered mental status)
Respiratory rate (score 1 if ≥ 22)
Systolic BP (score 1 if ≤ 100)

Question 25

Mental status (score 1 if altered mental status)
Respiratory rate (score 1 if ≥ 22)
Systolic BP (score 1 if ≤ 100)

What scoring system is this?

Answer 25

qSOFA (quick Sepsis Related Failure Assessment)

aims to identify patients at increased risk of poor outcomes outside the ITU environment.

Question 26

UTI - Patients with… should receive urgent review by a senior clinician and a MET/Peri-arrest call if indicated. All patients with significant infection should have a senior review.

Answer 26

haemodynamic instability, a lactate greater than 2 or evidence of end-organ dysfunction (or any other reason for concern)

Question 27

Three In - sepsis 6 UTI

Answer 27

Patients should receive high flow oxygen to achieve appropriate target saturations. A target of 94-98% is appropriate for the majority of patients. Those at risk of carbon dioxide retention (COPD) should have a target of 88-92%. IV fluids should be started, often 500ml of crystalloid over 15 minutes with reference the patient’s haemodynamic status and co-morbidities. Antibiotics are key and should be given without delay, NICE recommend empirical treatment with piperacillin/tazobactam (tazocin).

Question 28

Three out - sepsis 6 UTI

Answer 28

A minimum of two sets of blood cultures should be taken. Ideally, this should happen prior to administration of antibiotics though they should not be a cause for delay. A serum lactate should be obtained normally via a blood gas (arterial or venous) to help assess the patient’s status. Urine output should be measured ideally with a catheter with a careful fluid balance recorded.

Question 29

The definitive diagnosis of a UTI is based on typical clinical features associated with positive laboratory evidence of …/…

Answer 29

The definitive diagnosis of a UTI is based on typical clinical features associated with positive laboratory evidence of pyuria +/- bacteriuria.

Question 30

In young, non-pregnant females, typical clinical features (e.g. dysuria, suprapubic pain) in the absence of vaginal symptoms, is highly suggestive of a UTI. In this patient group, the probability of a UTI is > …%. Further laboratory testing offers little to the diagnosis, however as a minimum, the majority of clinicians would do a urine dip.

Answer 30

In young, non-pregnant females, typical clinical features (e.g. dysuria, suprapubic pain) in the absence of vaginal symptoms, is highly suggestive of a UTI. In this patient group, the probability of a UTI is > 90%. Further laboratory testing offers little to the diagnosis, however as a minimum, the majority of clinicians would do a urine dip.

Question 31

In the presence of complicating factors (e.g. systemic upset, diabetes, pregnancy, recurrent UTIs), further laboratory testing is necessary. Urinalysis, involving a urine dipstick and urinary … is key

Answer 31

In the presence of complicating factors (e.g. systemic upset, diabetes, pregnancy, recurrent UTIs), further laboratory testing is necessary. Urinalysis, involving a urine dipstick and urinary microscopy, culture & sensitivity, (MC&S), is key.

Question 32

A urine dipstick is useful to measure the presence of … and …

Answer 32

A urine dipstick is useful to measure the presence of leucocyte esterase (an enzymes released by WBCs, which reflects pyuria) and nitrites. The latter is because common urinary tract pathogens are able to convert nitrate into nitrite.

The presence of both leucocytes and nitrites is strongly associated with a UTI, however, the absence of one or both of these findings does not rule out a UTI if there is still a high clinical suspicion.

Question 33

The presence of both … and … is strongly associated with a UTI, however, the absence of one or both of these findings does not rule out a UTI if there is still a high clinical suspicion.

Answer 33

The presence of both leucocytes and nitrites is strongly associated with a UTI, however, the absence of one or both of these findings does not rule out a UTI if there is still a high clinical suspicion.

Question 34

Urinary MC&S

Answer 34

A urinary MC&S may identify the infecting microorganism and can help guide antibiotic sensitivities.

This is essential for patients with recurrent UTIs where resistance may have developed to previously used antibiotics.

Question 35

Further investigations - UTI

Answer 35

Further testing involves the use of blood tests and radiological investigations. These may be warranted in those who do not respond to treatment, present with a severe infection, have an atypical infection or underlying co-morbidities.

A full blood count, urea & electrolytes and a CRP forms the basic screen of blood tests. They may show raised inflammatory markers and impaired renal function. The latter is particularly important to assess for the development of an acute kidney injury (AKI).

Radiological investigations are usually reserved for complicated pyelonephritis or uncomplicated UTIs that do not respond to conventional antibiotic therapy. It can include both ultrasonography and computed tomography. They are useful for the assessment of abscesses, haemorrhage, calculi, obstruction and emphysematous pyelonephritis.

Question 36

Management of UTIs involves the prescription of appropriate antibiotic therapy according to local guidelines and concordance with any culture results.

Answer 36

The choice of antibiotic, route of administration and duration of therapy is dependent on multiple factors. These may include sex, severity, sensitivities, infecting organism and response to treatment. Some example regimes are shown below.

In those presenting with features of sepsis, a full assessment including sepsis six (and any other investigations indicated by review) and senior review should be sought.

Question 37

Acute uncomplicated UTIs can generally be managed with antibiotics such … OR …

Answer 37

Acute uncomplicated UTIs can generally be managed with antibiotics such as trimethoprim or nitrofurantoin. The former should be avoided in pregnancy and the latter in renal impairment. A typical course of trimethoprim may be 200 mg BD for 3 days in women or 7-14 days in men. Nitrofurantoin is given at a dose of 50 mg QDS or 100 mg MR BD for 3 days in women or 7-14 days in men.

Acute uncomplicated pyelonephritis that does not require admission to hospital can be treated with a course of an oral fluoroquinolone such as 500 mg of ciprofloxacin 12-hourly for 14 days.

Question 38

Acute uncomplicated pyelonephritis that does not require admission to hospital can be treated with a course of an oral … such as 500 mg of ciprofloxacin 12-hourly for 14 days.

Answer 38

Acute uncomplicated pyelonephritis that does not require admission to hospital can be treated with a course of an oral fluoroquinolone such as 500 mg of ciprofloxacin 12-hourly for 14 days.

Question 39

Intravenous … (e.g. 1.2 g 8-hourly, adjusted based on renal function) or ceftriaxone may be used for patients with urosepsis or acute severe pyelonephritis.

Answer 39

Intravenous co-amoxiclav (e.g. 1.2 g 8-hourly, adjusted based on renal function) or ceftriaxone may be used for patients with urosepsis or acute severe pyelonephritis.

Question 40

Acute complicated cystitis may be treated with an oral course of a …. In the presence of more severe disease (e.g. urosepsis) or patients unable to tolerate oral therapy, broad-spectrum IV antibiotics can be used.

Answer 40

Acute complicated cystitis may be treated with an oral course of a fluoroquinolone. In the presence of more severe disease (e.g. urosepsis) or patients unable to tolerate oral therapy, broad-spectrum IV antibiotics can be used.

Question 41

Catheter-associated UTIs

Answer 41

A urinary catheter or other indwelling catheter (e.g. suprapubic) is a major risk factor for the development of a UTI.

A catheter-associated UTI is diagnosed in the presence of bacteriuria (> 103 CFU/ml) of a uropathogenic organism in the presence of clinical features suggestive of a UTI without another possible source of infection.

Asymptomatic bacteriuria is common in catheterised patients and as such the diagnosis should take the clinical picture into account.

Question 42

Catheter-associated UTIs

What microorganisms typically cause these?

Answer 42

Microorganisms causing catheter-associated UTIs are similar to those causing normal UTIs (e.g. E. coli most common). However, other species such as Enterococcus, Candida, Pseudomonas and Klebsiella should also be considered.

Treatment involves the use of appropriate antibiotic therapy as with all UTIs. Ideally, an infected urinary catheter should be removed or changed under antibiotic coverage.

Question 43

Define cystitis

Answer 43

Cystitis is inflammation of the bladder, usually caused by a bladder infection

Question 44

Upper UTI - kidney and proximal ureter

Answer 44

Both = pyelonephritis

Just proximal ureter = pyelitis

Question 45

E.coli - gram stain colour

Answer 45

red - gram negative

Question 46

Staph aureus gram stain?

Answer 46

Violet blue

Question 47

Clavulanate potassium is a potassium salt of clavulanic acid. Clavulanic acid is a beta-lactamase inhibitor.

Answer 47

Beta-lactamases are enzymes which open the beta-lactam ring of beta-lactam antibiotics (e.g. penicillins and cephalosporins) rendering them inactive. Clavulanic acid acts to prevent these enzymes taking effect.

Question 48

What is the definition of a significant bacteriuria?

A > 100 colony forming units (CFU)/ml
B > 1,000 colony forming units (CFU)/ml
C > 10,000 colony forming units (CFU)/ml
D > 100,000 colony forming units (CFU)/ml
E > 1,000,000 colony forming units (CFU)/ml

Answer 48

A significant bacteriuria is defined as > 100,000 colony forming units (CFU)/ml
CFU is a measure of viable bacterial cells. A significant bacteriuria is highly indicative of UTI whilst lower levels may simply indicate contamination.

Question 49

Approximately …% of patients with indicative symptoms and a nitrite positive dipstick will have a UTI.

Answer 49

Approximately 90% of patients with indicative symptoms and a nitrite positive dipstick will have a UTI.

Question 50

Which immunoglobulin protects the bodies mucosal surfaces (including the urothelium)?

A	IgA
B	IgD
C	IgE
D	IgG
E	IgM

Answer 50

IgA is found on the bodies various mucosal surfaces including the intestines, respiratory tracts, oral mucosa and urothelium.
It helps prevent attachment and invasion of the urothelium by pathogens.

Question 51

Trimethoprim is a …
It has action against both gram-negative and gram-positive bacteria. It is one of the front-line antibiotics used in the treatment of urinary tract infections. It has little activity against anaerobes and pseudomonas. As a folate antagonist, it should be avoided in pregnancy. Adverse effects include nausea and vomiting, diarrhoea, rash and pruritus.

Answer 51

Trimethoprim is a dihydrofolate reductase inhibitor.
It has action against both gram-negative and gram-positive bacteria. It is one of the front-line antibiotics used in the treatment of urinary tract infections. It has little activity against anaerobes and pseudomonas. As a folate antagonist, it should be avoided in pregnancy. Adverse effects include nausea and vomiting, diarrhoea, rash and pruritus.