Urinary tract infections Flashcards
What differentiates upper urinary tract from lower urinary tract?
Above bladder = upper urinary tract
What flora is found within the urinary tract (kidneys/ureter, bladder and urethra)?
Kidneys/ureters = sterile Bladder = usually considered sterile but may not be the case Urethra = Perineal flora (skin/lower GI tract flora)
What is the predominant skin flora making up the perineal flora?
Coagulase negative staphylococci
What lower GI tract flora can make up part of the perineal flora? 3
1) Anaerobic bacteria
2) Aerobic bacteria - enterbacertiacae
3) Gram-positive cocci - enterococcus spp.
What is cystitis?
Lower urinary tract infection
What 5 components make up the syndrome of cystitis?
1) Dysuria
2) Urinary frequency
3) Urgency
4) Supra-pubic tenderness/ pain
5) Polyuria, nocturia, haematuria
What is pyelonephritis?
Upper urinary tract infection - infection of kidney and or renal pelvis
What are the 3 main symptoms of pyelonephritis?
1) Loin/abdominal pain/ tenderness
2) Fever
3) Other evidence of systemic infection eg. rigors, nausea, fever, diarrhoea, elevated CRP and WBC
What is urethral syndrome?
Also called abacterial cystitis or frequency-dysuria syndrome - symptoms of lower UTI without demonstratable infection
Which group does urethral syndrome commonly affect?
Women - 30-50 years of age
How is significant bacteriuria classified, what does that indicate?
10^5 cfu/ml (colony forming units)
Indicated likely UTI
What levels of bacteria indicate probable UTI?
10^4-10^5 cfu/ml
What are the 4 main limitations of defining significant bacteriuria and using this as an indicator of UTI?
1) Bacterial count is on a normal curve
2) Many symptomatic females have bacterial counts less than that considered significant bacteriuria
3) Lower counts 10^3cfu/ml are considered significant in males
4) Not relevant to catheter urine or sterile-aspirate urine
What is asymptomatic bacteriuria?
Significant bacteriuria with a single organism
With no symptoms of urinary tract infection
What is sterile pyruria?
Pus cells in urine
No organisms grown
Give 6 predisposing factors for UTI?
1) Female sex - 10:1
2) Urinary stasis (pregnancy, prostatic hypertrophy, stones, strictures, neoplasia, residual urine)
3) Instrumentation - eg. cystoscopy
4) Sexual intercourse
5) Fistuale - recto-vesical, vesico-vaginal
6) Congenital abnormalities - vesico-ureteric reflex
Give 3 sources of infection in UTI?
1) Perineum - movement of bacteria along a lumen
2) Fistulae - Movement of bacteria from genital/GI tract to urinary tract
3) Haematogenous (rare) - seeding of infection from the blood
What is the most common bacteria to cause UTI both in general practise and in hospital?
E coli
What is the second most common bacterial cause of UTI in general practise?
Staphylococcus saprophyticus
What is the second most common bacterial cause of UTI in hospitals?
Enterococcus spp.
What are the 3 causes of sterile pyuria?
1) Inhibition of bacterial growth - unprescribed abx, specimen contaminated with antiseptic
2) Fastidious (hard to grow) organisms - eg. mycobacterium TB, haemophilus spp., Neisseria gonorrhoeae and anaerobes
3) Urinary tract inflammation - renal or bladder stones, other renal disease
What is a catheter UTI?
Long-term indwelling catheterization results in bacteriuria
What 2 things is it important to distinguish between in catheter UTI, how are the distinguished?
Need to distinguish between colonisation and infection
Do so through looking at clinical features
How many catheter UTI lead to bacteraemia, how can this be avoided?
Manipulation or catheter removal may result in bacteraemia - prophylactic Abx may be used to prevent this in people with a hx of this problem, purulent discharge at site or colonisation of catheter exit site with staph aureus
Which 4 investigations can be carried out in someone with suspected UTI?
1) Dipstick testing (urinalysis)
2) Blood tests
3) Microbiology
4) Imaging
When is dipstick testing of no clinical value in suspected UTI?
In people with indwelling catheters unless these have been changed very recently
What 4 things does urine dipstick testing identify?
1) Blood
2) Protein
3) Nitrite
4) White blood cells (leucocyte esterase)
What 2 samples can be used for microbiological testing in suspected UTI?
1) Blood
2) Urine
What are the 4 types of urine sample?
1) Mid stream - MSU
2) Catheter urine - CU
3) Clean catch
4) Supra-pubic aspirate - SPA
Give one special test which may be used in suspected urinary tuberculosis?
Early morning urine (EMU) x 3
Whole contents of bladder
Used in suspected urinary tuberculosis
Give 4 indications for further investigations including renal tract USS and specialised tests in UTI?
1) Recurrent UTI
2) Any UTI in male patient
3) Any UTI in childhood
4) Pyelonephritis
What are the 5 requirements of Abx used to treat UTI?
1) Present in urine
2) Minimally toxic
3) Effective against likely organisms
4) Easily administered
5) Cheap
Give 4 examples of Abx used to treat UTI?
1) Nitrofurantoin
2) Pivmecillinam
3) Trimethoprim
4) Fosfomycin
What is the treatment for cystitis in women?
Treatment pre-empts microbiology results
Short course of Abx - 3 days
What is the treatment for cystitis in women with recurrence of symptoms or in males?
Longer course of Abx - 7 days
What are the 2 stages of treatment for pyelonephritis?
1) Empiric therapy - cefuroxime, ciprofloxacin, piperacillin-tazobactam (if >65)
2) Targeted therapy based on sensitivity reports for 7-14 days depending on Abx used
What 3 groups of people are treated for asymptomatic bacteriuria and why?
1) Pregnant - association with upper UTI, pre-term delivery and low birth weight babies
2) Infant - prevention of pyelonephritis and renal damage
3) Prior to urological procedures - prevention of UTI/bacteraemia
Do the elderly and catheterised require Abx for asymptomatic bacteriuria?
No, they do not require Abx
What type of urine sample is required is suspected UTI?
Mid stream
