Microbiology of UTI Flashcards Preview

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Flashcards in Microbiology of UTI Deck (83):
1

In a normal urinary tract, where is the urine sterile and where might it pick up bacteria?

Sterile - kidney, ureter, bladder
Distal urethra is colonised by bowel flora (coliforms & enterococci)

2

Define UTI

Presence of bacteria in urine which is causing clinical infection

3

Define lower and upper UTI

Lower UTI - infection confined to bladder (cystitis)
Upper UTI - infection involving ureters +/- kidney (pyelonephritis)

4

Define complicated UTI

UTI associated with systemic sepsis OR stones OR urinary tract abnormality

5

Define bacteriuria

Bacteria in the urine

Nb - common in elderly people with catheters & does not always denote infection

6

Cystitis is infection of the bladder. T/F

False - inflammation of the bladder; infection is one cause but there are others

7

Who is at highest risk of UTI?

Women
Catheterised patients
Patients with structural abnormalities of the urinary tract

8

Why are women more at risk of UTI?

Shorter & wider urethra
Proximity of urethra to anus
Increased risk with sexual activity & pregnancy

9

Describe ascending infection

Bowel bacteria on perineal skin -->
Urethra -->
Bladder -->
Ureter -->
Kidney

10

Describe bloodstream infection

Bacteraemia/septicaemia -->
Kidneys (multiple small abscesses)

11

What organisms commonly cause UTI?

E.coli
Klebsiella
Enterobacter

(more rarely proteus & other coliforms)

12

What are the features of UTI commonly associated with Proteus?

Calculi formation
Foul smelling urine

13

How does proteus cause the formation of renal stones?

Produces urease which breaks down uric acid into ammonia --> higher blood pH --> formation of salts

14

What are enterococci? Name two

Types of streptococci which live within the GI tract
Enterococci faecalis and faecium

15

What types of staph can cause UTI? State whether they are coagulase positive or negative

Staph. saphrophyticus (neg)
Staph aureus (pos)

16

Who gets staph. saphrophyticus infection?

Women of child bearing age

17

Pseudomonas aeruginosa is a gram negative bacillus of the coliform family. T/F

False - not a coliform

18

What is pseudomonas aeruginosa infection associated with?

Catheterisation
Instrumentation

19

How is pseudomonas aeruginosa infection treated?

Ciprafloxacin (resistant to other oral antibiotics)

20

What are the clinical symptoms and signs of UTI?

Dysuria
Frequency
Nocturia
Haematuria

21

What are the clinical symptoms and signs of UTI with upper tract involvement?

Fever
Rigors
Flank/loin pain

22

What is important to remember about collecting urine samples? How is this overcome?

Bacterial contamination from the perineum is common on first samples.
Midstream specimen of urine (MSSU)

23

Describe how midstream specimen of urine is collected

Perineum/meatus is washed with sterile saline
Sterile foil bowl given to patient
First pass urine on toilet
Mid urine collected in bowl
Last pass urine on toilet

24

Apart from MSSU, how else can urine be collected? When are these indicated

Clean catch - children & elderly
Bag urine - babies
Catheter specimen urine - catheter in
Suprapubic aspiration - outflow obstruction

25

List one drawback and one positive about bag urine collection?

Often contaminated with bowel flora
Negative culture results are reassuring

26

Which two containers can be used for urine collection? State the timeframes in which they should be delivered to the lab, respectively

Boricon container - 24 hours (preservative)
Sterile universal container - 2 hours

27

Which results on dipstick urine testing would indicate infection?

Leukocyte (WBC in urine)
Nitrite (bacteria in urine)
Blood
Protein

28

Which bacterias will not test positive for nitrites on dipstick?

Enterococci (which is absolutely fabulous because they're a common pathogen)

29

Which two tests can be done on the urine in a laboratory? When are these indicated?

Microscopy - urgent cases (look for pus, bacteria & red cells)
Culture - significant bacteraemia suspected

30

Describe Kass's criteria for defining urine culture results. Who does this criteria apply to?

>10^5 organisms/ml - probable UTI

31

Mixed growth in urine culture is not significant as UTIs are usually caused by one infecting organism. T/F

True - single organism in large majority of patients but may not stand true for those who are catheterised or who have structural abnormalities

32

What are ESBL producing bacteria?

Extended spectrum beta lactamase producing bacteria (i.e bacteria resistant to all cephalosporins and most penicillins)

33

Which antibiotics may be useful against ESBL producing bacteria?

Nitrofurantoin (oral)
Temocilin (IV)
(& others)

34

What are carbapenemase producing enterbacteria (CPE)?

Gram negative coliform bacilli that are resistant to Meropenem (i.e all current antibiotics)

35

How does CPE resistance spread? What are some strains associated with?

Plasmids
Travel to indian sub-continent

36

What are the features of an antibiotic useful in treating UTI?

Excreted in high concentrations in urine
Few side effects
Oral

37

How long a course of antibiotics should be given to uncomplicated lower UTI's in women?

3 days

38

What are the first line antibiotics for UTI?

Amoxicillin (IV or oral)
Trimethoprim (oral or IV cotrimoxazole)
Nitrofurantoin (oral)
Gentamicin (IV)

39

What are the second line antibiotics for UTI?

Pivmecillinam (oral)
Temocillin (IV)
Cefalexin (oral)
Co-amoxiclav (IV, oral)
Ciprofloxacin (IV, oral)

40

Is amoxicillin safe in pregnancy?

Yes

41

Which organisms will amoxicillin treat?

Enterococci faecalis
Some coliforms (50% are resistant)

42

How does trimethopram work?

Inhibits bacterial folic acid synthesis

43

Is trimethopram safe in pregnancy?

Avoid in first trimester (3 months)

44

What is co-trimoxazole a combination of?

Trimethopram and sulphamethoxazole

45

What risk do sulphonamides carry?

Stevens Johnsons syndrome (i.e toxic epidermal necrolysis)

46

Which organisms will trimethopram treat?

Most coliforms
Staph aureus
MRSA

NOT pseudomonas

47

In which clinical presentation of UTI is nitrofurantoin useful? Why?

Lower uncomplicated UTI
Only reaches effective concentrations in bladder urine

48

Is nitrofurantoin safe in pregnancy?

Avoid in late pregnancy (neonatal haemolysis) , breast feeding and in children

49

Which organisms will nitrofurantoin treat?

Most coliforms
Staph aureus
MRSA

NOT proteus or pseudomonas

50

Is gentamicin safe in pregnancy?

No

51

What does gentamicin toxicity cause? How common is this?

Renal toxicity
8th cranial nerve damage (deafness and balance issues)

Narrow therapeutic index - must be carefully monitored

52

How is gentamicin administered? What then must be checked?

Once daily IV infusion (7mg/kg)
Must check blood levels 6-14 hours later

53

Which organisms will gentamicin treat?

Most coliforms
Staph aureus
MRSA

NOT enterococci

54

When is gentamicin clinically indicated? How long for?

Severe gram negative (i.e coliform) sepsis
NO MORE THAN 3 DAYS

55

Pivmecillinam is useful in what clinical context?

Lower uncomplicated UTI

56

What bugs is pivmecillinam effective against?

Resistant coliforms

57

What bugs is pivmecillinam NOT effective against?

Strep
Staph
Pseudomonas
Enterococci

58

Can pivmecillinam be used in pregnancy?

Nope

59

Which bugs is temocillin effective against? Which is it NOT effective against?

Resistant coliforms

Strep
Staph
Enterococci
Pseudomonas

60

Temocillin is useful in which clinical context?

Complicated UTI/urosepsis where the patients renal function isn't good enough to introduce gentamicin

61

Can cefalexin be used in preganancy?

Yes

62

Why is cefalexin not used if it can be avoided?

Broad spectrum antibiotic increases risk of c.diff infection

63

Which organisms do cefalexin treat?

Coliforms
Staph

64

What is co-amoxiclav?

Combination of amoxicillin and clavulanic acid

65

Is co-amoxiclav safe in pregnancy?

Yes

66

Which organisms does co-amoxiclav treat? Why is it not used more often?

Staph
Coliforms
Enterococci

C.diff infection risk

67

When is ciprofloxacin not used?

Young children
Pregnant woman

68

Why is ciprofloxacin not used more often?

C.diff infection risk because broad spectrum antibiotics

69

Which organisms does ciprofloxacin treat? Why is worth remembering about this antibiotic?

Pseudomonas
Coliforms
Enterococci
Only ORAL agent that treats pseudomonas

70

How is female lower UTI treated?

Trimethoprim OR
Nitrofurantoin orally
3 days

71

How is uncatheterised male UTI treated?

Trimethoprim OR
Nitrofurantoin orally
7 days

72

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

Co-amoxiclav OR
Co-trimoxazole
14 days

73

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

Amoxicillin/co-trimoxazole AND gentamicin
3 days
Step down treatment

74

When can you diagnose asymptomatic bacteraemia?

>10^5 organisms/ml
Asymptomatic patient
NO pus in the urine

75

How is asymptomatic bacteraemia treated?

It isn't - especially not in old people

76

How is asymptomatic bacteraemia treated in a pregnant woman? What happens if you don't treat?

Antibiotics
May develop into pyelonephritis -->
Intra-uterine growth retardation (IUGR) or premature labour

77

What is abacterial cystitis/urethral syndrome?

UTI symptoms
Pus in urine
No significant growth in culture

78

What can the cause of abacterial cystitis?

Early phase of UTI
Urethral trauma
Chlamydia/gonorrhoea causing urethritis

79

What is honeymoon cystitis?

Urethral trauma due to vigorous sexual intercourse

80

How can urethral syndrome be treated?

Alkalising the urine for symptomatic relief

81

Does catheterisation increase the incidence of UTI? What increases the risk?

Yes
Increasing length of catheter

82

When should catheterised patients be given antibiotics?

>10^5 organisms/ml
Symptomatic

83

Giving unnecessary antibiotics to catheterised patients causes what?

Colonisation of catheter with increasingly resistant organisms

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