UTI Flashcards
Name the 4 parts of the urinary system where infection occurs
Urethra, ureters, kidneys, bladder
Where do bacteria enter through
Urethra
Which bacteria causes UTI
Escherichia Coli (gram negative)
What symptoms occur in bladder (cystitis)
Polyuria (peeing more than normal), dysuria (burning when urinating), lower abdominal discomfort
What symptoms occur in urethra (urethritis)
Burning on passing urine, discharge
Why can differential diagnosis include STI
Due to the proximity of the urethra to the vagina
List risk factors for UTI
- More common in females (shorter urethra, proximity to the anus)
- Postmenopausal women (decline in circulating oestrogen)
- Indwelling catheters
- Recent antibiotic use (disrupts flora)
- Spermicides (irritation & attachment sites for E coli)
- Sexual intercourse (bacteria to urinary tract)
- Pregnancy
List reasons for referral
- Pregnancy (pyelonephritis - kidney infection, premature birth, rupture of membranes and other complications)
- Men
- <16 years
- Symptoms of pyelonephritis (fever, loin pain, nausea/vomiting, flu-like illness)
- Signs of sepsis (altered behaviour, increased HR, low BP, anuria (lack of urine production)
- Non-response to first antibiotics
Who not to carry urine dipstick on
Over 65 years as asymptomatic bacteria common in this age and therefore unnecessary antibiotics
Which part of urine is tested
Mainstream
Why we don’t use urine culture often
Results not available straight away therefore uncomplicated infections will have resolved by then
How many days of antibiotics prescribed for non-pregnant uncomplicated lower UTI cases
3-day course
When do we prescribe antibiotics for UTI
Women under 65 with 2 or more key symptoms and no other causes (STI/sepsis)
When do we not prescribe antibiotics
No symptoms unless pregnant
What is urethritis
Inflammation post sexual intercourse
How do we differentiate between pyelonephritis and sepsis?
- Pyelonephritis (kidney pain/back pain, flu like illness, nausea/vomiting)
- Sepsis
(altered mental state, increased RR/HR, low BP, anuria, mottled skin, rash)
How do we diagnose UTI?
Dysuria, new nocturia, cloudy urine
- 2/3 present (UTI likely & dipstick not needed)
- 1 present (perform dipstick)
- 0 present (check urgency, visible haematuria - blood in urine, frequency, suprapubic tenderness)
If yes to other symptoms, perform dipstick, otherwise consider other diagnoses
What if a dipstick is negative for nitrites, leukocytes and RBC?
UTI less likely
What if dipstick is negative for nitrites and positive for leukocytes?
Could be UTI, send urine culture and consider treatment depending on symptom severity
What if a dipstick is positive RBC with positive nitrite or leukocyte?
Likely UTI, treat or wait with back up depending on symptom severity
What is the key differences between over and under 65?
- No urine dipsticks, new onset dysuria or 2 new symptoms of UTI, always send urine culture, delirium considerations/other diagnostics
Who is there seperate guidance for?
Children, pregnant women and men
What screening do pregnant women receive as part of antenatal care?
MSU (mid-stream specimen of urine) screening
How are pregnant women treated if suspected UTI?
- Symptomatic relief with paracetamol
- Prescribe antibiotic (check suitable)
- Send MSU for culture
- Amend prescription if needed
- If a group B streptococcus is isolated, prophylactic antibiotics will be offered during labour and delivery
What to consider for antibiotics
- How severe the symptoms are
- Risk of complications
- Previous urine culture results & antibiotic use
When to use a back up antibiotic?
If no improvement at 48 hours or if symptoms worsen at any time
List risk factors for increased resistance
- Care home resident
- Recurrent UTI (2 in 6 months, ≥ 3 in 12 months)
- Unresolving urinary symptoms
- Hospitalisation for > 7d in last 6 months
- Recent travel to country with increased resistance
- Previous UTI resistance to trimethoprim, cephalosporins or quinolones
What to do if there is a risk of resistance?
Always safety net & send for urine culture and susceptibilities
What do antibiotics increase the risk of?
Clostridium difficile (severe diarrhoea & in worst cases life-threatening damage to the colon)
Risk increased with broad spectrum antibiotics
What is the difference between trimethoprim and nitrofurantoin?
- Trimethoprim (narrow spectrum, resistance common)
- Nitrofurantoin (broad spectrum, resistance rates much lower)
What are the first choice of antibiotics?
- Nitrofurantoin MR if eGFR > 45ml/min 100mg BD for 3 days
- Trimethoprim 200mg BD for 3 days
What are the second choice of antibiotics?
- Nitrofurantoin MR if eGFR > 45ml/min and not first choice, same dose
- Pivmecillinam (penicillin) > 400mg initial then 200mg TDS for 3 days
- Fosfomycin > 3g single dose sachet
What is the MOA of nitrofurantoin?
Concentrated in urine (bactericidal) reduced by bacterial flavoproteins to reactive intermediates which inactivate/alter bacterial ribosomal proteins
When to avoid nitrofurantoin?
If eGFR is <45ml/min/1.73m2
Why is nitrofurantoin not effective in renal impairment?
Antibacterial efficacy depends on renal secretion of the drug into the urinary tract
Why do we take nitrofurantoin with food?
To increase bioavailability
What does nitrofurantoin do to the urine
Darkens urine colour (yellow/brown)
What are contraindications of nitrofurantoin?
- eGFR low, GP6D deficiency, acute porphyria (abnormal metabolism of haemoglobin), infants <3 months
What are adverse effects of nitrofurantoin?
- GI (minimised by taking with food/milk)
- Dizzy/tired
- Itchy rash/allergic reaction/swollen salivary glands
- Peripheral neuropathy (caution in diabetes patients) discontinue if signs
- Pulmonary reactions
- Discontinue treatment if unexplained pulmonary, hepatotoxic, haematological or neurological syndromes occur
What is the MOA of Trimethoprim?
Inhibits DHFR therefore blocks the reduction of dihydrofolate to tetrahydrofolate, the active form of folic acid by susceptible organisms
Inhibitory activity for most gram-positive aerobic cocci and some gram-negative aerobic bacilli
What to do with trimethoprim in renal impairment
Dose reductions may be needed if severe renal impairment
What does trimethoprim interact with?
Methotrexate, Warfarin
Therefore can cause hyperkalaemia so caution with other drugs that increase K+ (e.g. ACEI)
What is trimethoprim contraindicated with?
Blood dyscrasias (imbalance of body fluids), first trimester pregnancy
List adverse effects of trimethoprim
- Mild GI disturbances
- Pruritus (itching) and skin rash
- Blood disorders (long term)
List some advice for self-care
- Adequate fluid intake
- Paracetamol for pain (or ibuprofen if appropriate and lower UTI)
- Cranberry juice or tablets (no good evidence)
- Hygiene (wipe front to back)
- Empty bladder soon after sexual intercourse
- Birth control
- Avoid potentially irritating female products as these can irritate the urethra
What is some future changes?
- Point-of-care tests for UTIs developed which may guide antimicrobial prescribing
- Faster more accurate results could improve outcomes and reduce resistance risk
