17 UTIs Flashcards
What are the major clinical urinary tract infection syndromes and what are their associated symptoms?
What are the defence mechanisms that protect from a urinary tract infection? (5)
- Regular flushing- voiding
- Antibacterial secretions in urine and urethra
- Vesico-ureteral valves
- Urine acidity
- Mucosal barriers
Identify some pathogens that are known to cause UTIs (and what patients they might affect).
- Gram-negative rods
- Enterobactericeae (coliforms)
- Eg Escherichia coli
- Enterobactericeae (coliforms)
- Gram-positive cocci
- Coagulase-negative staphylococci
-
Staphylococcus saprophyticus
- Young women and hosptialised patients
-
Staphylococcus saprophyticus
- Coagulase-negative staphylococci
Other (hospitalised patients= susceptible)
Pseudomonas aeruginosa
What host factors cause an increased liklihood of acquiring a UTI (eg short urethra in females)?
Outline the pathogenesis of UTIs caused by bacterial factors (ie how do they overcome a patients normal defence mechanisms? Give examples
How should a urine sample (investigating a suspected UTI) be collected and stored?
- Collection:
- Midstream urine (avoid contamination- discard first part)
- Storage:
- Refrigerated
- Collected in container with boric acid
What tests can be carried out on a urine sample? (REMEMBER interpretation of culture results- depend on clinical details)
- Dipstick
- WBCs (leukocyte esterase)
- Nitrite (presence of nitrate-reducing bacteria)
- Blood
- Lab
- Microscopy- RBCs, WBCs, squamous epithilial cells
- Culture- number of bacterial colonies
Why might repeat specimens be required? (50% of women with clinical features of cystitis don’t have positive urine cultures)
-
Why?
- Low bacterial count
- Evidence of contamination
- Sterile pyuria (WBCs with no bacterial growth)
-
What may have caused this?
- Prior antibiotic
- Urethritis (eg chlamydia)
- Vaginal infection
- Non-infective inflammation eg tumour/chemicals
- Urinary tuberculosis (collect 3 early morning urine samples if suspected)
- Appendicitis
Outline how UTIs should be treated:
Useful graph showing UTI prevalence by age- male and female
What are the virulence factors for E.coli?
Differentiate between the symptoms that might present with a lower UTI and an upper UTI:
Dysuria may also be caused by other causes of urethral inflammation (urethritis), give some of these other causes:
What is the definition of an ‘uncomplicated UTI’?
- Normal urinary function
- Normal bacteria (eg e.coli)
- Patient has normal urinary tract
Males and females- any age
What is the definition of a complicated UTI?
1+ factors - predisposing to persistent infection/ recurrent infection/ treatment failure
Eg.
- Abnormal urinary tract
- Virulent organism (staph aureus)
- Impaired host defence
- Impaired renal function
In what circumstances might ‘uncomplicated UTIs’ need to be considered as ‘complicated’?
If uncomplicated in men, children, pregnant women
In what circumstance would a urine culture for a (suspected) UTI need to be carried out?
Complicated UTI
What substances in the urine can be detected with a urine dipstick?
Blood
Urea
Nitrites
Ketones
Glucose
Leucocyte esterase
pH
Protein
In which patients is a urine dipstick not useful?
Patients >65yrs (asymptomatic infection= common)
Catheterised patients
(will have positive dipstick even in absence of infection)
If a patient presents with dysuria, nocturia and cluody urine is a dipstick necessary?
No- high chance of UTI
Useful microscopic view of acute UTI and contaminated urine
What might we be looking for if imaging of the urinary tract is carried out on a patient with a UTI? (4)
Why is asymptomatic bacteriuria only screened for in pregnancy? (Common in elderly and indwelling catheters)
Pregnancy- untreated–> hgiher risk for premature labour and pyelonephritis
In what circumstances might a 5-7 day course of antibiotics be given for a lower UTI? (rather than 3 days)
- Complicated UTI:
- Male
- Pregnant
- Underlying disorders
Name some anitbiotics which can be used to treat uncomplicated UTIs. Which of these should not be given again within 3 months?
Nitrofurantoin
Trimethoprim (high resistance in leicester)
Pivmecillinam
Fosfomycin
Name some antibiotics which can be used to treat a complicated UTI:
- Nitrofurantoin
- Trimethoprim
- Pivmecillinam
- Fosfomycin
- Cefelexin
Name which antibiotics should be used to treat pyelonephritis/septicaemia.
(consider systemic activity and nephrotoxicity)
(NOT nitrofurantoin/fosfomycin- no systemic activity)
- Co-amoxiclav
- Ciprofloxacin
- Gentamicin (IV only and nephrotoxic)
When might prophylaxis be given to a patient for UTIs?
>3 epidodes in one year and no treatable underlying condition
- eg trimethoprim, nitrofurantoin*
- Document any breakthrough infections*
