Lecture 8.1: Urinary Tract Infections Flashcards
What is a UTI?
Presence and multiplication of microorganisms in one or more structures of the urinary tract with organisms invading the surrounding tissues
Uncomplicated UTI Definition
UTI caused by typical pathogens in people with a normal urinary tract and kidney function, and no predisposing co-morbidities
Complicated UTI Definition
UTI with an increased likelihood of complications such as persistent infection, treatment failure and recurrent infection
What is Bacteriuria?
The presence of bacteria in the urine
What is a Lower UTI?
An infection of the bladder or urethra
What is a Upper UTI?
An infection of the ureters and/or kidneys
What is a Recurrent UTI?
- 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
What is considered a Relapsed UTI?
<7 days, same organism
What is considered a Reinfection UTI?
> 14 days, any organism
What is Catheter Associated UTI?
Symptomatic infection of bladder or Kidney in catharised person
Who gets UTIs?
- 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
What is Cystitis?
Cystitis is inflammation of the bladder, usually caused by an infection
What is Pyelitis?
It is an inflammation of the mucous membrane of the pelvis and calyces of the kidney
What is Pyelonephritis?
It is an inflammation of the mucous membrane of the pelvis, calyces of the kidney AND infection of the parenchyma
What are some general Risk Factors for UTI? (3)
- Increased Age
- Sex: Female
- History of UTI
What are the Risk Factors for UTI?: Via Bacterial Entry
- Shorter Urethra
- Catheter
- Sexual Activity
- Incontinence
- Immunocompromised
What are the Risk Factors for UTI?: Via Urine Stasis (4)
- Prostate (BPH)
- Urethral Strictures
- Stones
- Pregnancy
What are the Risk Factors for UTI?: Via Changes to Flora (3)
- ABx Use
- Diabetes
- Menopause
How do bacteria enter the urinary tract? (3)
- Retrograde: ascending infection from
urethra - Via blood/lymphatics
- Direct (catheter, surgery,
instrumentation)
Which organisms are common causes of uncomplicated UTIs?
- Escherichia coli (in 60 to 85% of cases,
“UPEC”) - Staphylococcus saprophyticus
(approximately 5–10% of cases,
young, “honeymoon cystitis”)
What are some (of the many) other pathogens that can commonly cause UTIs?
- Proteus mirabilis (more common in
males, associated with calculi) - Psuedomonas aeruginosa (often.
hospital-acquired, antibiotic resistant) - Fungal & viral causes (candida,
herpes, adenovirus in children)
Bacterial virulence factors involved in infection in UTIs? (2)
- Adhesion: fimbriae and adhesins
allow attachment to uroepithelium - K antigens: capsule resistant to
phagocytosis
Natural Defences against UTIs (5)
- 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
What is Urethral Syndrome?
It is symptomatic abacteriuria, where you present with the clinical features of cystitis do not have positive urine cultures
What are possible reasons for Urethral Syndrome? (4)
- 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
Symptoms of UTIs (8)
- 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
What on a Urine Dipstick is indicative of an UTI? (at least 1 or 2 of these)
- Nitrites: Positive
- Leucocytes: Positive
- RBCs: Positive
Cultures for UTIs are not routinely done, under what circumstances are they done? (8)
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
What are the Methods for Urine Collection for a Culture? (3)
- Mid-stream Urine (MSU) sample
preferred - Catheter technique
- Pad sample
Treatment of Uncomplicated Lower UTI
- Short course of ABx (women 3 days,
men 7 days) or delay - Nitrofurantoin (check eGFR) or
Trimethoprim first line (but see local
guidelines)
Treatment of Pyelonephritis
- Cefalexin or co-amoxiclav PO/IV
- Supportive measures (fluids,
analgesia) - ALWAYS safety net
- Guided by results of culture
What is Asymptomatic Bacteriuria?
Isolation of bacteria in an appropriately collected urine specimen from an individual without symptoms of urinary tract infection (UTI)
Should be Asymptomatic Bacteriuria Treated?
- 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
What percentage of patients who undergo short-term catheterisation (2-4 days) develop bacteriuria?
- Between 10% and 30%
What percentage of patients who undergo long-term catheterisation develop bacteriuria?
- Between 90% and 100%
How to UTIs present in Children? What is the course of action for Treatment?
- 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
First Line Antibiotics for Uncomplicated UTI (2)
- Trimethoprim
- Nitrofurantoin
