UTIs Flashcards
What is an uncomplicated UTI
Bacterial infection of a structurally/functionally normal urinary tract
Can include acute cystitis in women (lower UTI) and
pyelonephritis (upper UTI)
What is a complicated UTI
Infection of a tract that is abnormal/predisposing conditions
- Structurally complicated (obstruction, stent, scarring)
- Functionally complicated (vesicoureteral reflux)
- Neurologically complicated
Most utis in men, pregnant women and children are considered complicated
Whats percentage of HCAIs are UTIs
2nd largest group of HCAI in UK
19.7% all HCAI infections. This will often be due to catheterisation
1 in 3 women will experience a UTI by 24y age
Does your risk of UTI increase with age?
Yes, over 60s have a 10% women, 3% men annual infection risk, over 80s have a 20% women 10% men risk
What is infected in:
urethritis
cystitis
pyelonephritis
urethra
bladder
kidney
What is the
cysto-ureteric valve
a structure which links the bladder and the urethra which moves up to the kidneys. It stops backflow of urine from the bladder to the kidneys
What are the host resistance factors to try to prevent UTIS
Bulk flow of urine - can flush any bacteria away from the urethra
Low pH and osmolarity - can lyse bacteria
Urine contains:
salts
organic acids - see above
Lactoferrin - sequests iron (prevents bacteria from being able to use any free iron)
Neutrophil influx
Bladder cell exfoliation - reduces bacterial load attached to bladder cells
What are some general host risk factors
In pre-menopausal women
Regular sexual intercourse - daily sex can increase likelihood of uti 9x
Spermicide that use
Nanoxynol-9 (USA) which disrupts normal vaginal microbiota. Decrease of helpful bacteria leads to more space for bad bacteria
Dehydration - decrease of bulk flow
Uropathogenic colonisation of GI tract - most uti bacteria derived from gut
Age - risk increases with age
Pregnancy - can introduce structural changes (enlarged uterus obstructs the ureta affecting urine bulk flow)
Indwelling medical device (catheter) - bypasses innate imune factors increases likelihood of biofilm
What is Vesicoureteral reflux
Urine flows backward from the bladder, up the ureter to the kidney due to a fault with the cysto-ureteric valve
Which bacteria cause UTIS (common and less common)
Common
Escherichia coli (70-95% cases)
Staphylococcus saprophyticus
Less Common *Klebsiella spp. *Enterobacter spp. *Proteus spp. *Citrobacter spp. Pseudomonas spp. Group B Strep Group D Strep Enterococci Corynebacterium urealyticum Yeasts
*all in the same family
What are the signs and symptoms of a UTI
Urinary urgency/frequency
Dysuria
Sensation of bladder fullness
Suprapubic tenderness
Bloody urine
How high is mortailty vs morbidity
Mortality from UTI is negligible. However, there is a significant morbidity
Mean 6.1 days of symptoms
Put these steps of infection of the urinary tract in order
Apoptosis and exfoliation of bladder epithelial cells
Adherence to uroepithelial cells by type 1 and p fimbriae
Contamination of periurethral area with uropathogenic E. Coli that has colonized the bowel
Invasion, intracellular multiplication observed for selected strains
influx of PMNs
Type 1 fimbriated e. coli selected at high CFU and low O2
Contamination of periurethral area with uropathogenic E. Coli that has colonized the bowel
Adherence to uro-epithelial cells by type 1 and pili/ fimbriae
Invasion, intracellular multiplication observed for selected strains
Apoptosis and exfoliation of bladder epithelial cells - innate defence mechanisms
Influx of PMNs (host inflammatory response)
Type 1 fimbriated e. coli selected at high CFU and low O2
Put these steps of infection of the urinary tract in order (part 2)
haemolysin damages epithelium
P fimbriae bind to renal tutbular epithelial cells
sat vacuolates epithelial cell and damages glomeruli
cytokines induced
e. coli crosses tubular epithelial cell barrier to initiate bacteraemia
E coli ascends to the kidney
E coli ascends to the kidney
There is a change in virulence factors - P fimbriae (not type 1 pili) bind to renal tutbular epithelial cells
cytokines induced
haemolysin damages epithelium
sat (protease virulence factor - toxin which can lead to host cell death) vacuolates epithelial cell and damages glomeruli leading to the presence of blood in the urine
e. coli crosses tubular epithelial cell barrier to initiate bacteraemia (enters blood supply)
What is the difference between pili and fimbrie
They are the same thing.
What are the signs and symptoms of pyelonephritis
Initially of cystitis but then…
severe lower back pain
Fever, chills, nausea and vomiting
Bacteraemia is often present
Costovertebral (CVA) tenderness (between the ribs and the backbone)
Elevated RBC in the urine and WBC casts can be seen (due to immune response)
What is the definition of reccurent utis
Two proven episodes of a UTI within 6 months or three episodes of a UTI within 12 months
Who is affected by recurrent utis
Reported in 27-48% healthy women
Very uncommon in healthy men
What can cause recurrent utis
- Voiding dysfunction
- Congenital anomalies (vesicoureteral reflux)
- Behavioural (again)
- Genetic risk factors
- Pod formation (biofilms in the bladder)
What influence do POD forming bacteria have on UTIs
POD communities of UPEC found in the bladder lumen may be a reservoir of viable bacterial cells which could be a cause of reccurent utis.
When do we prescribe back up antibiotics
For women with uncomplicated UTIs before test results have come back. If symptoms haven’t resolved within 48hrs prescription should be used. In all other cases, immediate antibiotic should be offered.
When do we refer patients with suspected utis onto hospital treatment
If a person aged 16+ has symptoms of a more serious uti (such as sepsis)
How do we diagnose UTIs
Using reported symptoms
Urine dipstick tests for: nitrites (indication of bacterial metabolism) leucocytes (due to immune response) protein blood
Mid Stream Sample of Urine (MSSU) to identify organism responsible - reduces contamination likelihood. Only done for complicated ones
What is the first line treatment for a lower uti for all women
Nitrofurantoin 100mg mr 2 times daily
3/7 non pregnant women
7/7 pregnant women
How does nitrofurantoin work
Targets dna and bacterial rna and is bacteriacidal
It concentrates in the urine
active against gram negative and gram positive
What is a second first line therapy for non pregnant women
trimethoprim 200mg 2x day 3/7
Targets bacterial dna synthesis and inhibits their growth
Not used in pregnant women because it can affect folate metabolism
How do we manage cystitis in the community pharmacy
medicines and advice
OTC potassium and sodium citrate (alkaline urine is less painful to pass)
OTC analgesia (dont use to delay attendance at gp)
Public health role
Differential diagnosis of STI, pregnancy
Which patients should we prefer if they present with uti symptoms
Pregnancy (higher risk of kidney infection)
Recurrent or non-resolving / worsening cystitis
Children and men
Symptoms suggestive of ascending infection (pyelonephritis)
Diabetes (elevated urine glucose levels can enhance bacterial growth)
What advice should be given to patients to prevent and control symptoms
Drink plenty of clear fluids (increased urine output)
Avoid caffeine (can encourage dehydration)
Empty bladder often and ensure full emptying (esp in children); wipe front to back
Empty bladder after sexual intercourse
Analgesia
When do we use cefalexin first line in UTI treatment
For the treatment of pyelonephritis. This is because nitrafurantoin shows poor tissue penetration in the kidney and lacks effective therapeutic concentrations in the kidney - it collects in the urine instead so good for lower utis
What are the issues around resistance in upec (inc. %resistance)
Various in vitro studies report UPEC insensitivity to:
Nitrofurantoin (10% isolates)
Trimethoprim (up to 70% isolates)
Regional variability
