Renal Microbiology

Question 1

What is the definition of UTI

Answer 1

Presence of microorganisms in the UT that are causing infection

Question 2

What is the definition of LUTI?

Answer 2

Infection confined to the Bladder (Cystitis)

Question 3

What is the definition of UUTI?

Answer 3

Infection confined to the Ureters and Kidneys (Pyelonephritis)

Question 4

Is the urine in the kidneys, ureters and bladder sterile?

Answer 4

True, although it is normal to see bacteria in elderly patients’ urine

Question 5

What is meant by Complicated UTI?

Answer 5

UTI complicated by the systemic symptoms/structural abnormality/stones

Question 6

What is Bacteriuria?

Answer 6

Bacteria in the urine.
Common in elderly patients with catheters and does NOT always mean infection.
Determine if patient symptomatic.

Question 7

List host factors for UTI

Answer 7

Genetic background 
Underlying disease - structural abnormality/catheterisation
Gender
Age 
Geographical Factors

Question 8

Why are host factors important for UTI?

Answer 8

Denotes recurrence possibility

Question 9

List 2 modes of UTI

Answer 9

Ascending

Bloodstream

Question 10

Who is more affected by UTIs, women or men?

Answer 10

Women
Shorter, wider distal urethra closer to the anus means they are more susceptible
Also increased risk with sexual activity and pregnancy

Question 11

List other patient groups predisposed to UTI

Answer 11

Catheterised patients
Patients with structural abnormality
Diabetics on SGLT2 Inhibitors

Question 12

How does UTI occur?

Answer 12

Contamination of the urethra leads to colonisation and subsequent infection

Question 13

What is Ascending UTI?

How does it occur?

Answer 13

Infection that tracks up from the bladder into the UT, often arising from:
Bacteria from bowel
Perineal Skin
Lower End of Urethra

Question 14

What is the biggest cause of UTI?

Answer 14

Coliforms, especially E.coli

Other coliform causes include:
Enterobacter 
Klebsiella 
Serratia 
Proteus

Question 15

What is the biggest gram negative, non-coliform bacterial causes of UTI?

Answer 15

Pseudomonas Aeruginosa

Question 16

What aids E.coli in its ability to cause disease?

Answer 16

Endotoxin
Flagellum
Fimbriae, help it attach on its way up the bladder

Question 17

What is Proteus UTI associated with?

Answer 17

Struvite stones (staghorn calculi)

These are large stones which take the shape of the renal calyx.
Urologists are needed to break them down

Question 18

How can Proteus be identified?

Answer 18

Foul smelling, smells like burnt chocolate

It produces urease to produce urea which increases urinary pH, increasing salt production

Swarming cultures on agar plate

Question 19

List other forms of urine specimen

Answer 19

Clean Catch Urine (used for children)
Bag Urine (babies), susceptible to contamination
Catheter Specimen of Urine, only if patient has symptomatic UTI
Suprapubic Aspiration

Question 20

Why is Pseudomonas Aeruginosa UTI important?

Answer 20

It is resistant to most oral antibiotics

Can only be treated with Quinolones i.e. Ciprofloxacin

Question 21

List other UTI investigations

Answer 21

Urine Microscopy (only for patients with nephrotic differentials e.g. casts)
Urine Culture (< 10^4 colonisation is Negative for infection)

Question 22

List gram positive causes of UTI

Answer 22

Enterococcus faecalis, which is a common bug of hospitalised patients (HAI)
Staphylococcus Saphrophyticus (women of child bearing age)
Staph. Aureus (associated with bacteraemia)

Question 23

List symptoms of UTI

Answer 23

Dysuria 
Increased Frequency 
Nocturia (establish change)
Haematuria 
Fever, Loin Pain or Rigors (UUTI indication)

Question 24

Antibiotics are required in asymptomatic bacteriuria

Answer 24

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

Question 25

Why is it important to be careful with antibiotics in catheterisation?

Answer 25

Catheter may become colonised with resistant bacteria

Question 26

How is a urine sample taken?

Answer 26

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

Question 27

Why is Gentamicin use limited to 3 days?

Answer 27

Due to risk of nephrotoxicity

Question 28

What is Abacterial Cystitis?

Answer 28

Syndrome consisting of: 
Frequency 
Nocturia 
Dysuria 
May be due to early phase of UTI, urethral trauma (Honeymoon Cystitis) or chlamydia/gonorrhoea urethritis

Question 29

How is female LUT treated?

Answer 29

Trimethoprim or nitrofurantoin orally (3 days)

Anti-inflammatory treatment may be as good as antibiotics for some cystitis patients

Question 30

How is UTI treated for an uncatheterised male?

Answer 30

Trimethoprim or nitrofurantoin orally (7 days)

Question 31

How is a Complicated UTI or GP presentation of Pyelonephritis treated?

Answer 31

Co-amoxiclav or co-trimoxazole (14 days)

Question 32

How is a Complicated UTI or Hospital Pyelonephritis treated?

Answer 32

Amoxicillin and Gentamicin IV for 3 days

Co-trimoxazole and gentamicin if penicillin allergy, stepdown as guided by antibiotic sensitivities

Question 33

How is ESBL UTI treated?

Answer 33

Pivmecillinam (oral)

Temocillin (IV)

Question 34

List first line antibiotics for UTI

Answer 34

Gentamicin
Amoxicillin (not always sensitive)
Trimethoprim
Co-trimoxazole (not reliable in bacteraemia)

Question 35

What is the Kass Criteria?

Answer 35

> 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