Urinary Tract Infections

Question 1

What is the definition of a UTI?

Answer 1

an infection of any part of the urinary system

Question 2

What is the definition of an infection?

What does infection lead to?

Answer 2

an infection is the invasion of body tissues by a pathogenic organism

this causes an immune response, giving rise to symptoms

Question 3

What is the most common type of pathogen causing a UTI?

Answer 3

in a UTI, the pathogen is often an endogenous bacteria that has got in the wrong place and invaded

Question 4

What are the predisposing factors to UTI?

Answer 4

• female sex
• urinary stasis
• urological instrumentation (including catheters)
• sexual intercourse
• fistulae (recto-vesical, vesico-vaginal)
• congenital abnormalities (vesico-ureteric reflux)

Question 5

What are common causes of urinary stasis?

Answer 5

• pregnancy
• prostatic hypertrophy
• stones
• strictures
• neoplasia
• residual urine from poor bladder emptying

Question 6

Which areas of the urinary tract are sterile and colonised?

Answer 6

• the kidneys are ureters are sterile
• the bladder is considered sterile, but this may not be the case
• the urethra contains perineal flora

Question 7

What makes up the perineal flora?

Answer 7

skin flora:

• mainly coagulase negative staphylococci

lower GI tract flora:

• ‘internal’ colonising bacteria are often found on the skin around the relevant orifice

enterobacterales:

• “coliforms” - enteric Gram-negative bacilli

Gram-positive cocci:

• Enterococcus spp.

Question 8

What endogenous source are most UTIs caused by?

Answer 8

most infections are caused by gut bacteria (enteric flora)

perineum:

• movement of bacteria along a lumen

fistulae:

• movement of bacteria from the genital/GI tract to the urinary tract

Question 9

What is the other cause of a UTI involving endogenous bacteria?

Answer 9

haematogenous spread

this is the seeding of bacteria to the urinary tract via the blood

e.g. Staphylococcus aureus

this is very rare

Question 10

What organisms commonly cause UTIs?

Answer 10

• E. coli
• Staphylococcus saprophyticus
• Proteus mirabilis
• Enterococcus spp.
• Klebsiella spp.
• other coliforms
• Pseudomonas aeruginosa

Question 11

What is the problem with knowing whether a bacteria is the cause of a UTI or whether it is local?

Answer 11

bacteria that cause UTIs can also:

• contaminate poorly taken samples
• colonise catheters
• cause asymptomatic bacteriuria (particularly in >65s)

Question 12

What is the key to diagnosis in UTIs?

Answer 12

clinical signs and symptoms are the key to diagnosis

AND

microbiology results guide you to the culprit and appropriate, directed treatment

Question 13

What is seen in asymptomatic bacteriuria?

Answer 13

no symptoms of a urinary tract infection

BUT

cultured urine sample will grow a single organism in significant numbers

Question 14

What is cystitis?

What are the signs and symptoms?

Answer 14

it is a lower UTI that is more common in women

• dysuria
• frequency
• urgency
• supra-pubic pain or tenderness
• polyuria, nocturia, haematuria

Question 15

What is pyelonephritis?

What are the signs and symptoms?

Answer 15

an infection of the kidney and/or renal pelvis

symptoms:

• all the symptoms of a lower UTI
• loin / abdominal pain or tenderness
• fever

other signs of systemic infection:

• rigors, nausea, vomiting, diarrhoea
• elevated CRP and WBCs

Question 16

What are the 2 different types of UTIs?

Answer 16

complicated or uncomplicated

Question 17

What is the difference between a complicated and uncomplicated UTI?

Answer 17

Complicated UTI:

• underlying abnormailty that is structural or functional
• e.g. urinary stasis - obstruction/retention
• presence of a foreign body
• e.g. catheter / renal calculi / biofilm

Uncomplicated UTI:

• in absence of above

Question 18

In which types of people should a complicated UTI be suspected unless confirmed otherwise?

Answer 18

children < 10-12

men < 65

Question 19

what is a catheter-associated UTI?

What are the risks and treatment?

Answer 19

indwelling catheterisation results in bacteriuria

biofilm formation has led to colonisation

manipulation or catheter removal may lead to bacteraemia

antibiotic prophylaxis can be indicated for some patient groups

Question 20

What types of patient groups would be indicated for antibiotic prophylaxis against a catheter associated UTI?

Answer 20

• previous symptomatic CA-UTI with catheter change/removal
• traumatic catheterisation (including 2 or more attempts)
• purulent urethral/suprapubic catheter exit site discharge
• catheter or meatal/suprapubic catheter exit site colonisation with Staphylococcus aureus (including MRSA)

Question 21

How is diagnosis of a catheter-associated UTI made?

Answer 21

diagnosis is made by clinical features

there is a need to distinguish between colonisation and infection

dipsticks are no use and “normal” / “sterile” results should not be expected

Question 22

What is a nephrostomy?

Answer 22

an artifical opening created between the kidney and the skin which allows for the urinary diversion directly from the upper part of the urinary system (renal pelvis)

this is performed if there is a blockage in the urinary tract

Question 23

What are the signs of infection following nephrostomy?

Answer 23

• fever
• pain and tenderness at the site
• haematuria or purulent discharge

Question 24

What is meant by an ileal conduit / urostomy?

Answer 24

a short section of the ileum is used to drain the ureters directly to a stoma on the anterior abdominal wall after cystectomy

Question 25

What signs might be seen if there was an infection following ileal conduit / urostomy?

Answer 25

* fever * ascending infection (upper UTI symptoms) * para-stomal skin infections - redness, swelling, pus

Question 26

Why is it important to recognise the symptoms of infection following nephrostomy or ileal conduit?

Answer 26

like catheters, colonisation of the tubing and bags occurs

Question 27

What is meant by **urosepsis**? What symptoms will be present?

Answer 27

systemic signs of infection related to any underlying urinary source of infection * fever * rigors * nausea, vomiting, diarrhoea * +/- haemodynamic compromise * raised inflammatory markers (CRP, WCC) often thought as akin to 'upper UTI', but there may not be clinical signs of pyelonephritis

Question 28

What are some common causes of urethritis?

Answer 28

* some STIs cause urethral symptoms * thrush (vulvovaginal candidiasis) causes irritation and dysuria * urethral syndrome

Question 29

What is meant by "urethral syndrome"? Who is most commonly affected?

Answer 29

symptoms of lower UTI without any demonstratable infection also known as abacterial cystitis and frequency-dysuria sundrome mostly affects 30-50 year old women

Question 30

What are the 2 different types of urinary tract abscesses?

Answer 30

perinephric and intra-renal

Question 31

What causes a peri-nephric urinary tract abscess?

Answer 31

**uncommon complication:** * renal stones and/or diabetics * secondary to obstruction of infected kidney **gram-negative bacilli**

Question 32

What causes an intra-renal urinary tract abscess?

Answer 32

**haematogenous spread:** * this can be unilateral, single or renal cortex * caused by *Staphylococcus aureus* **classic acute pyelonephritis:** * in the cortex or medulla

Question 33

what is prostatitis? What are the signs and symptoms?

Answer 33

inflammation of the prostate **signs & symptoms:** * lower urinary tract symptoms * fever * tender tense prostate on PR palpation * acute retention

Question 34

Which pathogens cause prostatitis? What are the risk factors associated with this condition?

Answer 34

**pathogens:** * normal urinary pathogens e.g. *E. coli* * can be caused by *S. aureus* **risk factors:** * procedures involving the prostate * indwelling urinary catheter

Question 35

What are the symptoms of chronic prostatitis?

Answer 35

* pain in and around the perineum and genitalia * lower urinary tract symptoms * enlarged or tender prostate on examination

Question 36

What are the causes of chronic prostatitis?

Answer 36

\>90% due to **chronic pelvic pain syndrome** this is non-bacterial and will have a negative urine culture **chronic bacterial prostatitis** caused by recurrent UTIs with the same organism and asymptomatic in-between

Question 37

If a diagnosis of UTI relies on clinical symptoms, what are the purposes of tests?

Answer 37

* to confirm clinical suspicion * to find out the pathogen and how best to treat it * to monitor response through inflammatory marker trends * imaging can be used to look for abnormalities in urinary tract anatomy, stones and abscesses this can guide the duration of therapy required

Question 38

Why is it important to find out the pathogen causing a UTI and how best to treat it?

Answer 38

this allows for a **directed approach** to treatment it confirms the empirical choice, or prompts change if needed the **narrowest spectrum** antibiotic possible can be given this reduces the impact on the patient's microbiome and reduces risk of C. diff

Question 39

What are the most common microbiological investigations for UTIs?

Answer 39

**dipsticks, ward-tests and urinalysis** this provides a quick screen, but has limitations and is only suitable for certain groups **laboratory testing of urine samples**

Question 40

When should dipsticks/ward-tests/urinalysis NOT be used? What are the guidelines surrounding their use in children?

Answer 40

do NOT use for catheter samples and unreliable in \>65y **children:** * do NOT use if \< 3 months * 3m - 3y can use but if high risk send for culture regardless of result * \>3y they are reliable

Question 41

What do dipsticks test for?

Answer 41

* blood * protein * nitrite * white blood cells (leukocyte esterase)

Question 42

What samples should be collected for microbiology lab tests?

Answer 42

**urine:** * mid-stream (MSU) * catheter urine (CSU) * paediatric samples - "clean catch", pad, bag * supra-pubic aspirate (SPA) **blood cultures:** * suspected pyelonephritis or severe sepsis

Question 43

What types of tests are performed on the urine samples?

Answer 43

microscopy, culture and sensitivity testing

Question 44

What types of clinical details should be sent to the lab with the urine sample? Why?

Answer 44

* age * gender * pregnant? * symptoms * antibiotics * allergies this allows the lab to determine what needs to be 'set up', what antibiotics to test and what growth is relevant

Question 45

Why is mid-stream urine used?

Answer 45

the inital stream will pick up the bacteria colonising the urethra the mid-stream better represents any bacteria actually in the bladder or higher urinary tract

Question 46

What types of bottles should mid-stream urine be collected in?

Answer 46

**sterile:** * should not be decanted into from non-sterile containers **preservative:** * e.g. boric acid ("red top") * this needs the right amount of urine but prevents overgrowth

Question 47

How are lab results on urine samples interpreted? What does a raised WCC, RCC and epithelial cells show?

Answer 47

if there is bacterial growth in the presence of clinical symptoms, this confirms diagnosis raised WCC indicates inflammation raised RCC indicates bleeding epithelial cells may indicate contamination if present

Question 48

What is meant by "sterile pyuria"?

Answer 48

pus cells (raised WCC) in the urine no organisms are grown with standard lab methods

Question 49

What can cause sterile pyuria?

Answer 49

**inhibition of bacterial growth:** * antibiotics - collect sample before starting if possible * specimen contaminated with antiseptic **"fastidious" (hard to grow) organisms:** * anaerobes * *Mycobacterium tuberculosis, Haemophilus* spp. **urinary tract inflammation:** * renal or bladder stones **urethritis (sexually transmitted pathogens)** * *Neisseria gonorrhoeae* * *chlamydia trachomatis*

Question 50

When might an early morning urine test (x3) be requested? What is needed specifically?

Answer 50

if suspected **urinary tuberculosis** need to request acid fast bacilli (AFBs) specifically this test has poor sensitivity and a tissue biopsy at the site of suspected disease would be better

Question 51

What are the indications for further non-microbiological investigations? What are these investigations?

Answer 51

* recurrent UTI * any UTI in a male patient * any UTI in childhood * pyelonephritis **investigations:** * renal tract ultrasound scan * CT KUB * specialised tests - isotope scans, micturating cystourethrogram

Question 52

What is involved in the non-antimicrobial management of UTIs?

Answer 52

* increased fluid intake * anti-inflammatories - NSAIDs, ibuprofen * device removal if no longer indicated if the device is still needed, it should be changed under prophylaxis * drainage is there is an obstruction or abscess

Question 53

When are recurrent UTIs deemed to be "significant"?

Answer 53

recurrent UTI can be caused by re-infection or bacterial persistence it is significant if there are 3 or more episodes within 12 months

Question 54

What are the requirements for a "good" UTI antibiotic?

Answer 54

* gets into urine * minimally toxic * effective against the likely organisms * easily administered * cheap

Question 55

What UTI antibiotics are commonly used?

Answer 55

* Nitrofurantoin inadequate for systemic infections and prostatitis so used in lower UTIs only * Pivmecillinam * Trimethoprim * Fosfomycin

Question 56

How is cystitis treated in females?

Answer 56

* treatment is often started before microbiology results * short course of antibiotics (3 days) * in mild cases, a delayed prescription is given and patient is told to increase fluids +/- ibuprofen

Question 57

What is the treatment of cystitis in males or recurrent cases?

Answer 57

* longer course of antibiotics - 7 days if there are recurrent UTIs in men - think PROSTATE

Question 58

What is the empiric therapy for pyelonephritis?

Answer 58

* broad action against likely urinary pathogens required * needs to be systemically active * cefuroxime, aztreonam, ciprofloxacin, gentamicin

Question 59

What is involved in the directed therapy for pyelonephritis?

Answer 59

this is based on sensitivity results and the narrowest spectrum agent possible is used not all oral agents are suitable for PO step-down e.g. cannot use nitrofurantoin for follow on treatment

Question 60

What is the duration of treatment for pyelonephritis?

Answer 60

7 - 14 days depending on antibiotic used

Question 61

What must an agent that is used to treat prostatitis be?

Answer 61

* it needs to be active against likely pathogens * it needs to penetrate the prostate most antibiotics have poor penetration into prostatic tissue penetration is better in the inflammation present in acute prostatitis

Question 62

What are the empiric and directed options used to treat prostatitis? what is the duration?

Answer 62

**empirical options:** * piperacillin-tazobactam (IV only) * ciprofloxacin (IV/PO) **directed options:** * as above * trimethoprim or co-trimoxazole **duration:** * 2-4 weeks

Question 63

Which patients should be treated for asymptomatic bacteruria?

Answer 63

**pregnant:** * associated with upper UTI, pre-term delivery and low birth weight **Infants:** * preventon of pyelonephritis and renal damage **prior to urological procedures:** * prevention of UTI/bacteriaemia elderly and catheterised patients DO NOT require antibiotics

Question 64

What lifestyle modification factors are undertaken in treatment of confirmed recurrent UTIs?

Answer 64

* increased fluid intake * review of contraception * voiding before and after sex * oestrogen replacement in post-menopausal women - local or oral

Question 65

What are the antimicrobial strategies used to treat confirmed recurrent UTIs?

Answer 65

continuous prophylaxis with **methanamine hippurate** no catheter and acidic urine needed continous antibiotic prophylaxis - urology guided this drives resistance, and therefore breakthrough infections with resistant organisms but may have short term benefit