Microbiology of Urinary Tract Infection Flashcards Preview

SM Renal > Microbiology of Urinary Tract Infection > Flashcards

Flashcards in Microbiology of Urinary Tract Infection Deck (65):
1

What part of the renal tract is colonised by bacteria

The distal end of the urethra

2

What type of bacteria is found in the distal end of the urethra

Coliforms and enterococci from the large bowel

3

What is the definition of a UTI

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

4

What is cystitis

Inflammation of the bladder that ay or may not be caused by an infection

5

What is a lower UTI

an infection that is confined to the bladder (cystitis)

6

What is an upper UTI

An infection involving the ureters +/ the kidneys (pyelonephritis)

7

Why is it important to determine whether the infection is upper or lower

Different antibiotics are used to treat different levels of the urinary tract

8

What is a complicated UTI

A UTI complicated by systemic sepsis or a urinary structural abnormality or stones

9

What patients are more likely to have bacteria in their urinary tract but not necessarily an infection

Patients with catheters or elderly patients

10

What is meant by bacteriuria

The presence of bacteria in the urine

11

Give 3 reasons that make women more susceptible to UTI than men

Short wide urethra
proximity of urehtra to anus is shorter
increased risk with sexual activity,
pregnancy (uterus presses down on the bladder resulting in incomplete emptying)

12

Ascending infection is more common. Describe how it occurs

Bowel organisms colonise the perineal skin. they travel to the lower end of the urethra, into the bladder, ureters and then kidneys

13

Describe how infection occurs from the blood

The patient has bacteraemia/ septicaemia from another focus of infection --> bacteria in blood --> seeded into kidney --> multiple small abscesses --> bacteria in urine

14

What organism is responsible for 70% of UTI

E Coli

15

What are almost all causal organisms

Gram negative bacilli

16

What are some other causal organisms

Coliforms
Klebstelle sp.
Enterobacter sp.
Proteus sp.

17

What is protest sp. associated with

the formation of stones (calculi)
They produce urease which changes urinary pH which causes precipitation of salts and this can result in the formation of stones

18

there are 2 common forms of Enterococcus spp.
Name them
What is more difficult to treat and why

Enterococcus faecalis and enterococcus faecium
Faecium is more difficult to treat as it is more resistant to antibiotics

19

What organism usually affects women of child bearing age

Staphylococcus saphrophyticus

20

What is pseudomonas aeruginosa associated with

UT instrumentation or catheters

21

What is the antibiotic that seems to be sensitive to pseudomonas aeruginosa.

What is the disadvantage of using it

Ciprofloxacin
Associated with C diff infection

22

How does pseudomonas aeroginosa behave differently to other coliforms

It grows aerobically

23

What are the signs and symptoms of a UTI

dysuria
frequency of urination
nocturia
haematuria

24

What are some signs of an upper urinary tract infection

fever
loin pain
rigors

25

How is the best specimen collected

Wash perineum / urethral meatus with sterile saline (not antiseptic)
Allow patient to pass first part in toilet. Collect second part which should have less organisms and not just urethral organisms
Pass last urine in toilet

26

Why should antiseptic not be used to wash the perineum

It can inhibit bacteria growth which may affect lab results

27

What is the difficulty with bag urine collection

It is often contaminated with bowel flora
A negative culture result is more useful than a positive as it can exclude infection from the differential

28

What might a clinician do lift he bag urine is positive

Suprapubic aspirate of urine

29

How is urine collected from a catheter for culture

Take from a collection port - not the bag

30

What is the best container to collect urine for sending to the lab

Boricon container (red top)
It contains the preservativeve boric acid which will stop bacteria multiplying for 24 hours

31

When might LEU be raised on dipstick

Catheterised patients

32

What organism does not give a positive nitrite test

Enterococci

33

If a patients urinalysis shows LEU, when should you send a sample

Only if they have signs and symptoms as well

34

What should we look for on microscopy of urine

Not done routinely but when we do we look for: presence of polymorphs (pus cells), bacteria +/- RBCs

35

When is a plate insignificant of a urine infection

10^3

36

When is a plate of urine definitive for UTI

10^5 organisms or more but usually only 1 organism shows huge numbers (not huge numbers of various organisms)

37

When might a urine plate be contaminated or show signs of an early UTI

10^4 organisms
Test should be repeated

38

What is the problem of using Kass's Criteria

It only applies to women of child bearing age

39

What is ESBL

Extended spectrum beta lactamase - this is an enzyme that breaks down the beta lactic rings in almost all cephalosporins and penicillins

40

Where is ESBL carried

on a plasmid

41

What are some antibiotics that may be useful for treating ESBL-producing bacteria

Nitrofurantoin - oral
Pivemecillinam - oral
Fosfomycin - oral
Tmocillin-IV
Meeropenem - IV
Ertapenem -IV

42

What is though to be one of the causes for the increasing incidence of ESBL producing bacteria

Imported chickens - they contain antibiotic strains

43

What are carbapenemase- producing enterobacteriaceae (CPE)

Gram negative (coliform) bacilli that are resistant to meropenem --> basically resistant to all antibiotics
This is the last choice antibiotic

44

Why did CPE become resistant

A lot of organisms are found in Asia. Uncontrolled use of antibiotics there

45

What are 4 ideal components of an antibiotic

Excreted in urine in high concentration
Oral
Inexpensive
Few side effects

46

Why is trimethoprim the first line AB in women

It inhibits bacterial folic acid synthesis - a range of organisms can be treated

47

Why is trimethoprim contraindicated in the 1st trimester of pregnancy

It inhibits folate synthesis --> spinabifida is associated with low levels of folic acid in pregnancy

48

How can trimethorprim be given

As co-trimoxaxole (IV or oral)

49

When would nitrofurantoin be given

In lower uncomplicated UTI -

50

When should nitrofurantoin be avoided

Late pregnancy
Breastfeeding

51

Why can Nitrofurantoin only be used for uncomplicated lower UTI

It is only activated in the urine

52

Why should gentamicin be avoided in pregnancy

Risk of hearing problems and kidney problem in the fetus
VIIIth nerve damage - deafness and balance problems

53

How long should gentamicin be prescribed for

3 days only - not 3 doses

54

What is the main advantages of using pivmecillinam

Very beta-lactamase stable - high activity against very antibiotic-resistant coliforms that produce extended spectrum beta-lactamases (ESBLs)
Less of a risk of C diff

55

When would Temocillin be used

It is useful for patients whose renal function is too poor for gentamicin but is not as effective

56

When is Cefalexin used

During pregnancy

57

What is co-amoxiclav made up of

amoxicillin and clavulanic acid

58

What does Ciprofloxacin do

Inhibit bacterial DNA gyros which prevents supercoiling of bacterial DNA

59

Who should not receive ciprofloxacin

Pregnant women or young children

60

What is the antibiotic of choice for a female lower UTI

Trimethoprim or nitrofurantoin
oral
3 days

61

What is the antibiotic of choice for an uncatheterised male UTI

Trimethoprim or nitrofurantoin orally
7 days

62

What is the antibiotic used for a complicated UTI or pyelonephritis (GP)

Co-amoxiclav or co-trimoxazole
14 days

63

What is the antibiotic used for a complicated UTI or pyelonephritis (hospital)

Amoxicillin and gentamicin IV for 3 days
Co-trimoxazole and gentamicin if penicillin allergic
Stepdown as guided by antibiotic sensitivities

64

Why are pregnant women treated for asymptomatic bacteriuria but other patients are not

If pregnant women are left untreated, 20-30% progress to pyelonephritis
This may lead to intra-uterine growth retardation or premature labour

65

What might help symptoms of bacterial cystitis / urethral syndrome

Alkalinising the urine may help