MB10 Urinary Tract Infections Flashcards
UTIs
- What are the difficulties?
- What is recurrent infection an indication of?
- What is the trend in
- Males
- Females
- Common, Life threatening, Complicated
- radiological investigation especially in children
- Trend
- Men get more complicated UTIs later in life because of prostate disease
- Women have acute, easier-treated UTIs (more likely to have them younger)
What are the main modes of acquisition of a UTI?
(most common in bold)
Ascending
Haematogenous
What are the factors that predispose to UTI?
Bacterial Factors
- Capsular Antigens
- Hemolysins
- Urease
- Adhesion to uroepithelium (e.g fimbriae in E.Coli)
- Introital colonisation
Host Factors
- Renal calculi
- Ureteric reflux
- Tumours in and adjacent to urinary tract
- Pregnancy, bladder stones
- Neurologic problems
- Incomplete bladder emptying
- large volume of residual urine
- Loss of sphincter control
- Prostatic hypertrophy
- Short urethra in women
- Catheterization
Define
- Uncomplicated UTI?
- Complicated UTI?
- UTI by a usual pathogen in a normal urinary tract in a person with normal renal function
- UTI where there is anatomical, functional, pharmacological factors predisposing to persistent infection
What will predispose to a complicated UTI?
Anatomical: stones, vesicoureteric reflux, neurogenic bladder, catheter, urinary obstruction
Multi-drug resistant organism: carbapenemase producing enterobacteriaceae (CPE)
Impaired host defence: diabetes mellitus, immunosuppressed
Impaired renal function or post renal transplant
What is the most common cause for urinary tract infections?
E.Coli
Organisms in community acquired are just as prominent in hospitalised, however there is a greater variety of UTI causing agents in the community.
- Which organisms live in the gut, can colonise the perineum and ascend up the urethra and colonise it?
- Which from the Non-Enterobacteriaceae is likely to cause UTIs?
- Which of the gram-positive cocci chains is likely to cause UTI?
- ENTEROBACTERIACEAE (gram negative rods) = Esherichia Coli, Klebsiella pneumoniae, Proteus mirabilis
- Pseudomonas aeruginosa
- Enterococcus faecalis
What are the clinical features of
- Acute lower UTIs
- Upper UTIs
- Dysuria, urgency, frequency, nocturia, strangury (feel like you need to go), haematuria, suprapubic pain, smell
- Fever, nausea, malaise, loin pain, tenderness
- What is Asymptomatic Bacteriuria
- How is it picked up?
- Who is it particularly importnant to screen?
- Significant numbers of bacteria in urine in absence of symptoms
- Screening
- Pregnant women, Young children, people undergoing instrumentation of the urinary tract (bacteremia), elderly and diabetics
How are UTIs normally diagnosed?
by symptoms
- Dipstick
- Culture and sensitivites
- Urine collection and lab analysis
- Special collections
Dipsticks
- What do they detect?
- What could the results indicate?
- Urinary nitrate (thought to be a metabolite produced by bacteria in the urine) and urinary leucocyte esterase (WBCs will be involved in an inflammatory response)
- +/+ =UTI very likely – treat empirically
- /- = UTI unlikely – no treatment unless…..
- /+ = Possible UTI – consider culture…..
When should Culture and Sensitivities be conducted in UTI diagnosis?
- Pregnancy - 1st antenatal visit or if symptoms
- Suspected pyelonephritis - (signs of upper UTI)
- Suspected UTI in men
- Recurrent UTI
- Catheterised – only if evidence of systemic infection
- Failed treatment or persistence
- Abnormal Urinary Tract
- Post Renal Transplant
UTI diagnosis - Urine Collection
- Normally, what state is the urine in the bladder?
- How should a sample be collected?
- When should it be cultured?
- What is the basis of the Mid-steam sample collection?
- How is it intially analysed?
- Sterile
- Clean- MSU- before antibiotics, Collected into sterile container
- Cultured within one hour or held at 4°C
- flushes away the transient colonisation of the perineurium. This next urine is actually the urine IN THE BLADDER
- Clear result in less than 24 hours = counting didn’t reach the threshold (WBCs and bacteria counted). If positive - ID and sensitivies (antibiotic sensitivity testing) (48hours)
UTI Diagnosis
- What constitutes an ‘infection’?
- What constitutes ‘contamination’?
- Properly collected MSU contain >105 CFU/ml of single bacterial spp (bacteria per ml)
- <104 CFU/ml – more than one spp
spp = SPECIES
What is the unit CFU?
colony-forming unit (CFU or cfu) is a measure of viable bacterial or fungal cells.CFU measures only viable cells. For convenience the results are given as CFU/mL (colony-forming unitsper milliliter) for liquids, and CFU/g (colony-forming units per gram) for solids.