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Flashcards in Microbiology Deck (43)
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1
Q

Define a UTI

A

The presence of micro-organisms in the urinary tract that are causing clinical infection

2
Q

Differentiate between an Upper and Lower UTI

A

Lower UTI = infection confined to bladder (cystitis)

Upper UTI = infection involving ureters +/- kidneys (pyelonephritis)

3
Q

The lower end of the urethra is usually colonised by what bugs and why?

A

bacteria (coliforms and enterococci from the large bowel - due to proximity of anus to urerthra)

4
Q

What is meant by a complicated UTI?

A

Pt has:
systemic symptoms
OR urinary structural abnormality /stones

5
Q

Bacteruria does NOT always mean infection. TRUE/FALSE?

A

TRUE - Bacteriuria just means bacteria present in urine

does not always mean infection,
esp. in elderly patients or patients with catheters

6
Q

Cystitis is caused by an infection. TRUE/FALSE?

A

FALSE
Cystitis is inflammation of the bladder
(not always due to infection)

7
Q

Why are women at more risk of a UTI than men?

A
  • short wide urethra
  • proximity of urethra to anus
  • increased risk with sexual activity, pregnancy
8
Q

What are the two main routes of infection with a UTI?

A
  • Ascending infection

- bloodstream

9
Q

What bacteria is usually responsible for UTIs?

A

E-coli

10
Q

What types of bacteria can be responsible for UTIs?

A

Lactose fermenting Coliforms (ecoli, Kelbsiella, enterobacter etc.)
Lactose non-fermenting coliforms (proteus, providencia)

Pseudomonas (Gm -ve bacilli but NOT a coliform)

11
Q

What features of E-coli contribute to its virulence?

A
Endotoxin = released in sepsis
Fimbriae = allow to adhere to the wall of urethra and climb upwards
12
Q

Describe when proteus would normally be found?

A

in Struvite Kidney stones

13
Q

Describe the presentation of proteus in the lab

A
Foul smelling (burnt chocolate)
Swarming cultures
14
Q

What does proteus produce and what does this cause?

A

Produces urease
=> breaks down urea to form ammonia (NH4+)
=> increases urinary pH - precipitation of salts

15
Q

When would you suspect a pseudomonas UTI?

A

Associated with catheters and instrumentation

16
Q

What antibiotic is the only oral option for a pseudomonas infection?

A

resistant to most oral antibiotics

except ciprofloxacin

17
Q

How does ciprofloxacin work?

A

Inhibits bacterial DNA gyrase

=> prevents “supercoiling” of bacterial DNA

18
Q

In what patients should ciprofloxacin be avoided?

A

young children

pregnant women

19
Q

What bugs does ciprofloxacin NOT cover?

A

Staph aureus or MRSA

20
Q

Where is an infection such as Enterococcus faecalis

most likely acquired?

A

In hospital

21
Q

Who is usually affected by Staphylococcus saphrophyticus UTIs?

A

women of child bearing age

22
Q

What symptoms indicate a lower urinary tract infection?

A

dysuria (pain passing urine)
frequency of urination
nocturia
haematuria

23
Q

What symptoms may indicate an upper urinary tract infection?

A

Fever
Rigors
Loin pain

24
Q

When do you want to take a specimen to check for evidence of UTIs?

A
  • Midstream specimen (as first pass of urine will be contaminated)
  • Suprapubic aspiration
  • Straight (in/out) catheter
25
Q

What container can be used for a urine specimen where it will take longer than 2 hrs to reach the labs?

A

Boricon container
contains boric acid to stop bacterial multiplying
works for ~24 hrs

26
Q

What patients should NOT undergo dipstick urine testing?

A

DO NOT DIPSTICK URINE OF THE ELDERLY

DO NOT DIPSTICK CATHETER SPECIMENS

27
Q

When is microscopy of urine used?

A

If cultures have been identified but the lab wishes to be more specific with the diagnosis

28
Q

Over what number of bacteria in a urine specimen would indicate an infection?

A

> 10^5

29
Q

What is an abacterial cystitis?

A

Patient has symptoms of UTI

Pus cells present in urine, but no significant growth on culture

30
Q

What can cause an abacterial cystitis?

A

early phase of UTI
urethral trauma - “honeymoon cystitis”
urethritis caused by chlamydia, gonorrhoea

31
Q

If antibiotics cannot be given, what treatment can provide symptomatic relief in abacterial cystitis?

A

Alkalinising agents

32
Q

When is asymptomatic bacteruria treated?

A

Treated with antibiotics in pregnancy.
If left untreated:
- may progress to pyelonephritis
=> lead to intra-uterine growth retardation (IUGR) or premature labour

33
Q

When should catheterised patients be given antibiotics?

A

When there is evidence of symptoms of infection

34
Q

How is a female Lower UTI treated?

A

Trimethoprim or nitrofurantoin orally (3 days)

35
Q

How is an uncatheterised male UTI treated?

A

Trimethoprim or nitrofurantoin orally (7 days due to prostatism risk)

36
Q

How is a complicated UTI/ pyelonehritis treated in the community?

A

Co-amoxiclav or co-trimoxazole (14 days)

37
Q

How is a complicated UTI/ pyelonehritis treated in hospital?

A

Amoxicillin and gentamicin IV for 3 days

38
Q

Why is gentamicin only used in hospital settings?

A

Can only be given IV

Narrow therapeutic index before toxicity

39
Q

What antibiotic should be given if a patient has an ESBL infecting organism?

A
Pivmecillinam (oral)
and Temocillin (IV)
40
Q

When should trimethoprim be avoided?

A

1st trimester (3 months) of pregnancy

41
Q

Why is amoxicillin not used first line to treat UTIs?

A

> 50% of coliforms including Ecoli are now resistant

42
Q

When would cefelexin potentially be used to treat a UTI?

A

If organism is amoxicillin and trimethoprim resistant

43
Q

What patient group is Temocillin useful for?

A

Useful in patients whose renal function is too poor for gentamicin

NOT as effective as gentamicin clinically