Renal Microbiology Flashcards
What is the definition of UTI
Presence of microorganisms in the UT that are causing infection
What is the definition of LUTI?
Infection confined to the Bladder (Cystitis)
What is the definition of UUTI?
Infection confined to the Ureters and Kidneys (Pyelonephritis)
Is the urine in the kidneys, ureters and bladder sterile?
True, although it is normal to see bacteria in elderly patients’ urine
What is meant by Complicated UTI?
UTI complicated by the systemic symptoms/structural abnormality/stones
What is Bacteriuria?
Bacteria in the urine.
Common in elderly patients with catheters and does NOT always mean infection.
Determine if patient symptomatic.
List host factors for UTI
Genetic background Underlying disease - structural abnormality/catheterisation Gender Age Geographical Factors
Why are host factors important for UTI?
Denotes recurrence possibility
List 2 modes of UTI
Ascending
Bloodstream
Who is more affected by UTIs, women or men?
Women
Shorter, wider distal urethra closer to the anus means they are more susceptible
Also increased risk with sexual activity and pregnancy
List other patient groups predisposed to UTI
Catheterised patients
Patients with structural abnormality
Diabetics on SGLT2 Inhibitors
How does UTI occur?
Contamination of the urethra leads to colonisation and subsequent infection
What is Ascending UTI?
How does it occur?
Infection that tracks up from the bladder into the UT, often arising from:
Bacteria from bowel
Perineal Skin
Lower End of Urethra
What is the biggest cause of UTI?
Coliforms, especially E.coli
Other coliform causes include: Enterobacter Klebsiella Serratia Proteus
What is the biggest gram negative, non-coliform bacterial causes of UTI?
Pseudomonas Aeruginosa
What aids E.coli in its ability to cause disease?
Endotoxin
Flagellum
Fimbriae, help it attach on its way up the bladder
What is Proteus UTI associated with?
Struvite stones (staghorn calculi)
These are large stones which take the shape of the renal calyx.
Urologists are needed to break them down
How can Proteus be identified?
Foul smelling, smells like burnt chocolate
It produces urease to produce urea which increases urinary pH, increasing salt production
Swarming cultures on agar plate
List other forms of urine specimen
Clean Catch Urine (used for children)
Bag Urine (babies), susceptible to contamination
Catheter Specimen of Urine, only if patient has symptomatic UTI
Suprapubic Aspiration
Why is Pseudomonas Aeruginosa UTI important?
It is resistant to most oral antibiotics
Can only be treated with Quinolones i.e. Ciprofloxacin
List other UTI investigations
Urine Microscopy (only for patients with nephrotic differentials e.g. casts) Urine Culture (< 10^4 colonisation is Negative for infection)
List gram positive causes of UTI
Enterococcus faecalis, which is a common bug of hospitalised patients (HAI)
Staphylococcus Saphrophyticus (women of child bearing age)
Staph. Aureus (associated with bacteraemia)
List symptoms of UTI
Dysuria Increased Frequency Nocturia (establish change) Haematuria Fever, Loin Pain or Rigors (UUTI indication)
Antibiotics are required in asymptomatic bacteriuria
No
Except for pregnant women as they may present with pyelonephritis or premature pregnancy later on
Pregnant women are screened for asymptomatic bacteriuria on first antenatal visit
Why is it important to be careful with antibiotics in catheterisation?
Catheter may become colonised with resistant bacteria
How is a urine sample taken?
First pass of urine is more likely to be contaminated so sample is taken from a midstream specimen as this is more useful and therefore, the best sample.
First pass = urine in toilet
Midstream specimen = sample after
Why is Gentamicin use limited to 3 days?
Due to risk of nephrotoxicity
What is Abacterial Cystitis?
Syndrome consisting of: Frequency Nocturia Dysuria May be due to early phase of UTI, urethral trauma (Honeymoon Cystitis) or chlamydia/gonorrhoea urethritis
How is female LUT treated?
Trimethoprim or nitrofurantoin orally (3 days)
Anti-inflammatory treatment may be as good as antibiotics for some cystitis patients
How is UTI treated for an uncatheterised male?
Trimethoprim or nitrofurantoin orally (7 days)
How is a Complicated UTI or GP presentation of Pyelonephritis treated?
Co-amoxiclav or co-trimoxazole (14 days)
How is a Complicated UTI or Hospital Pyelonephritis treated?
Amoxicillin and Gentamicin IV for 3 days
Co-trimoxazole and gentamicin if penicillin allergy, stepdown as guided by antibiotic sensitivities
How is ESBL UTI treated?
Pivmecillinam (oral)
Temocillin (IV)
List first line antibiotics for UTI
Gentamicin
Amoxicillin (not always sensitive)
Trimethoprim
Co-trimoxazole (not reliable in bacteraemia)
What is the Kass Criteria?
> 10^5 organisms/ml = significant =probable UTI
<10^3 organisms/ml = not significant bacteriuria
10^4 organisms/ml = contaminated? infection? Repeat specimen
CAUTION; these criteria ONLY apply to women of childbearing age
