Lecture 8.1: Urinary Tract Infections

Question 1

What is a UTI?

Answer 1

Presence and multiplication of microorganisms in one or more structures of the urinary tract with organisms invading the surrounding tissues

Question 2

Uncomplicated UTI Definition

Answer 2

UTI caused by typical pathogens in people with a normal urinary tract and kidney function, and no predisposing co-morbidities

Question 3

Complicated UTI Definition

Answer 3

UTI with an increased likelihood of complications such as persistent infection, treatment failure and recurrent infection

Question 4

What is Bacteriuria?

Answer 4

The presence of bacteria in the urine

Question 5

What is a Lower UTI?

Answer 5

An infection of the bladder or urethra

Question 6

What is a Upper UTI?

Answer 6

An infection of the ureters and/or kidneys

Question 7

What is a Recurrent UTI?

Answer 7

• Usually defined as two or more
  episodes of UTI in six months or three
  or more episodes in one year
• Can be due to either Relapse or
  Reinfection

Question 8

What is considered a Relapsed UTI?

Answer 8

<7 days, same organism

Question 9

What is considered a Reinfection UTI?

Answer 9

> 14 days, any organism

Question 10

What is Catheter Associated UTI?

Answer 10

Symptomatic infection of bladder or Kidney in catharised person

Question 11

Who gets UTIs?

Answer 11

• Acute UTI- up to 50% of all women in
  their lifetime
• 1/3 of women will have had episode
  cystitis by 24 yrs.
• 20-30% women who have a UTI will
  have recurrence

Question 12

What is Cystitis?

Answer 12

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

Question 13

What is Pyelitis?

Answer 13

It is an inflammation of the mucous membrane of the pelvis and calyces of the kidney

Question 14

What is Pyelonephritis?

Answer 14

It is an inflammation of the mucous membrane of the pelvis, calyces of the kidney AND infection of the parenchyma

Question 15

What are some general Risk Factors for UTI? (3)

Answer 15

• Increased Age
• Sex: Female
• History of UTI

Question 16

What are the Risk Factors for UTI?: Via Bacterial Entry

Answer 16

• Shorter Urethra
• Catheter
• Sexual Activity
• Incontinence
• Immunocompromised

Question 17

What are the Risk Factors for UTI?: Via Urine Stasis (4)

Answer 17

• Prostate (BPH)
• Urethral Strictures
• Stones
• Pregnancy

Question 18

What are the Risk Factors for UTI?: Via Changes to Flora (3)

Answer 18

• ABx Use
• Diabetes
• Menopause

Question 19

How do bacteria enter the urinary tract? (3)

Answer 19

• Retrograde: ascending infection from
  urethra
• Via blood/lymphatics
• Direct (catheter, surgery,
  instrumentation)

Question 20

Which organisms are common causes of uncomplicated UTIs?

Answer 20

• Escherichia coli (in 60 to 85% of cases,
  “UPEC”)
• Staphylococcus saprophyticus
  (approximately 5–10% of cases,
  young, “honeymoon cystitis”)

Question 21

What are some (of the many) other pathogens that can commonly cause UTIs?

Answer 21

• Proteus mirabilis (more common in
  males, associated with calculi)
• Psuedomonas aeruginosa (often.
  hospital-acquired, antibiotic resistant)
• Fungal & viral causes (candida,
  herpes, adenovirus in children)

Question 22

Bacterial virulence factors involved in infection in UTIs? (2)

Answer 22

• Adhesion: fimbriae and adhesins
  allow attachment to uroepithelium
• K antigens: capsule resistant to
  phagocytosis

Question 23

Natural Defences against UTIs (5)

Answer 23

• Low pH, high concentration of urea
• Regular flushing: removes bacteria
  from distal urethra
• Mucin layer
• Antibacterial secretions by urothelium
  into the mucin layer (RNAse 7,
  cathelicidn, Tamm-Horsfall protein)
• Inflammation & exfoliation of cells

Question 24

What is Urethral Syndrome?

Answer 24

It is symptomatic abacteriuria, where you present with the clinical features of cystitis do not have positive urine cultures

Question 25

What are possible reasons for Urethral Syndrome? (4)

Answer 25

* Infection with low counts of bacteria * Infection with fastidious organisms not detected on routine culture * Sexually transmitted infections e.g. Chlamydia * Non-infective inflammation e.g. chemical

Question 26

Symptoms of UTIs (8)

Answer 26

* Dysuria (burning/pain upon urination) * Polyuria (increased frequent urination) * Urgency (a strong need/desire to empty the bladder) * Nocturia (PU more often at night) * Suprapubic tenderness/discomfort * Changes in urine (cloudy, colour change, odour change) * Haematuria (blood in urine) * Backpain, fever, loin pain, rigors = consider Pyelonephritis

Question 27

What on a Urine Dipstick is indicative of an UTI? (at least 1 or 2 of these)

Answer 27

* Nitrites: Positive * Leucocytes: Positive * RBCs: Positive

Question 28

Cultures for UTIs are not routinely done, under what circumstances are they done? (8)

Answer 28

Culture when higher risk of complication: * Pregnancy * >65 yrs (if sx and antibx given) * Suspected pyelonephritis * Suspected UTI in men * Failed antibiotic treatment or recurrent symptoms * Recurrent UTI * Abnormalities of the GU tract * Renal impairment

Question 29

What are the Methods for Urine Collection for a Culture? (3)

Answer 29

* Mid-stream Urine (MSU) sample preferred * Catheter technique * Pad sample

Question 30

Treatment of Uncomplicated Lower UTI

Answer 30

* Short course of ABx (women 3 days, men 7 days) or delay * Nitrofurantoin (check eGFR) or Trimethoprim first line (but see local guidelines)

Question 31

Treatment of Pyelonephritis

Answer 31

* Cefalexin or co-amoxiclav PO/IV * Supportive measures (fluids, analgesia) * ALWAYS safety net * Guided by results of culture

Question 32

What is Asymptomatic Bacteriuria?

Answer 32

Isolation of bacteria in an appropriately collected urine specimen from an individual without symptoms of urinary tract infection (UTI)

Question 33

Should be Asymptomatic Bacteriuria Treated?

Answer 33

* Unless patient has systemic symptoms, not to be treated * Does not reduce morbidity/mortality * Does increase antibiotic resistance & risk of side effects * Except in pregnancy, then you treat it

Question 34

What percentage of patients who undergo short-term catheterisation (2-4 days) develop bacteriuria?

Answer 34

* Between 10% and 30%

Question 35

What percentage of patients who undergo long-term catheterisation develop bacteriuria?

Answer 35

* Between 90% and 100%

Question 36

How to UTIs present in Children? What is the course of action for Treatment?

Answer 36

* Often present with non-specific. symptoms – consider other causes * If under 3 months, refer urgently to paeds * Otherwise dipstick * Culture – clean catch, pad, catheter, suprapubic * Ultrasound if complicated – assess for structural abnormalities * Only re-culture if complicated UTI

Question 37

First Line Antibiotics for Uncomplicated UTI (2)

Answer 37

* Trimethoprim * Nitrofurantoin