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Year 2 - Renal (DP) > Microbiology > Flashcards

Flashcards in Microbiology Deck (114):
1

Urine in what areas is usually sterile?

Kidneys
Ureters
Bladder

2

What microbes are commensals in the lower urethra?

Coliforms
Enterococci
Anaerobes (rarely cause UTI)

3

What is cystitis?

Infection in bladder (Lower UTI)

4

What is an upper UTI?

Infection involving ureters

5

What is pyelonephritis?

An upper UTI involving the kidneys

6

What is a complicated UTI?

UTI complicated by:
- Sepsis
- Abnormality/Stones

7

What effect does a complicated UTI have on treatment?

Requires a longer antibiotics course

8

When might bacteruria not be an infection?

In the elderly
Patients with catheters

9

Why are females much more prone to UTIs?

Short and wide urethra
Urethral opening close to anus

10

What can increase the risk of UTIs?

Sex
Pregnancy

11

Why do posterior urethral valves increase the UTI risk?

Incomplete bladder emptying:
-> Urine stasis -> Infection

12

What is the most common route of UTI? What route does it take?

Ascending infection
Bowel bacteria -> Perineal skin -> Lower urethra -> Bladder -> Ureters -> Kidneys

13

How can a descending UTI occur?

1. Patient with bacteraemia/sepsis
2. Bacteria seeded in kidney
3. Multiple small abscesses -> Bacteruria

14

What are coliforms?

Rod-shaped, gram negative, non-spore forming, facilitative anaerobes

15

What is the most common causal organism in UTIs?

E. coli (70%)

16

What other coliforms can cause UTIs?

Klebsiella sp
Enterobacter sp.
Other

17

What are Proteus sp. UTIs associated with? How do they cause this?

Stone formation:
- Produce ureases
- Urea broken down into ammonia
- Urinary pH rises
- Precipitates salt formation

18

Proteus sp. UTIs have what other distinguishing feature?

Foul smelling

19

What are Enterococcus sp?

Types of Strep. living in the GI tract

20

Which of the following is antibiotic sensitive and which can be resistant and difficult to treat:
- Enterococcus faecalis
- Enterococcus faecium

Faecalis:
- Antibiotic sensitive
Faecium:
- Can be resistant and difficult to treat

21

Who gets UTIs caused by Staphylococcus saphrophyticus?

Women of child-bearing age

22

Why is Pseudomonas not a coliform?

Strictly aerobic

23

What are Pseudomonas UTIs associated with?

Catheters
Urinary tract instrumentation

24

What is the only antibiotic that can treat Pseudomonas UTIs and what does this increase the risk of?

Ciprofloxacin:
- Increased risk of C. diff

25

What symptoms suggest an upper UTI?

Fever
Loin pain
Rigors

26

What urine is likely to be infected in obtaining a urine sample?

1st urine (collects commensals from perineum and lower urethra)

27

What (ideally) needs to be carried out before obtaining a MSSU?

Wash perineum and urethral meatus with saline:
- Not antiseptic (May kill bacteria)

28

When would a clean catch urine sample be used?

In children and elderly when MSSU can't be obtained

29

In what individuals is a bag urine sample used?

Babies

30

What do you do if there is a positive culture from a bag urine sample?

Suprapubic specimen must be taken

31

When would you take a catheter specimen of urine?

If signs/symptoms of UTI

32

What is the best container for containing urine for transport?

Boricon container:
- Contains boric acid
-> Stops bacterial multiplication for ~24 hours
- Red top

33

If a universal sterile container is used to transport urine samples, how soon must it reach the lab?

In 2 hours

34

What does a positive leukocyte esterase mean on urine dipstick?

Indicates WBC in urine

35

What might give a false positive result on leukocyte esterase on dipstick?

Catheter

36

What does a positive nitrite result on urine dipstick mean?

Bacteruria

37

Why do bacteria cause a positive nitrite result on urine dipstick?

Nitrate is reduced to Nitrite

38

What bacteria cause a positive nitrite result?

Coliforms

39

What bacteria do not cause a positive nitrite result?

Enterococcus

40

Ideally, when should a MSSU only be sent?

If dipstick is positive and there are symptoms

41

When is urine microscopy used?

If it is an urgent case

42

What should you look for in urine microscopy?

Polymorphs (pus cells)
Bacteria
+/- RBCs

43

What is a significant urine culture result according to the Kass' Criteria?

>100,000 (10^5) organisms/ml

44

What is a insignificant urine culture result according to the Kass' Criteria?

45

If on urine culture there are 10^4 organisms/ml, what might this indicate?

Contamination?
UTI?

46

If there are only 10^4 organisms/ml on urine culture what should you do?

Repeat specimen

47

In a patient who is not catheterised, what does urine culture usually show?

Single organism
>10^5 organisms/ml of pure growth

48

If there is mixed growth on urine culture, even if >10^5 organisms/ml, what does this mean?

Usually insignificant unless they have urinary tract abnormalities

49

What does ESBL stand for?

Extended Spectrum β-Lactamase

50

ESBL-producing bacteria are resistant to what?

All cephalosporins
Almost all penicillins

51

What is the ESBL-producing gene carried on and what is it usually carried with?

On a plasmid with other resistance genes:
- Gentamicin
- Ciprofloxacins

52

What oral antibiotics may be useful in treating ESBL-producing bacteria?

Nitrofurantoin
Pivmecillinam
Fosfomycin

53

What IV antibiotics may be useful in treating ESBL-producing bacteria?

Temocillin
Meropenem
Ertapenem

54

What is a possible source of ESBL-producing bacteria?

Imported chicken:
- Antibiotics used as growth factors
-> Resistance

55

What are Carbapenemase-Producing Enterobacteriaceae?

Gram-negative bacilli (coliforms) that are resistant to meropenem:
- Essentially resistant to all antibiotics

56

What are Carbapenemase-Producing Enterobacteriaceae associated with?

Travel to the Indian sub-continent

57

What are the features of an ideal antibiotic used for UTIs?

Excreted in high concentrations in the urine:
- If metabolised in liver -> Useless
Oral
Inexpensive
Few side effects

58

What length of treatment is usually adequate for an uncomplicated, lower UTI in women?

3 days

59

When is a urine sample sent in uncomplicated, lower UTIs in women?

If they have a second UTI relatively soon after the 1st

60

Which of the following is not a 1st line antibiotic for UTIs:
- Amoxicillin (PO/IV)
- Co-amoxiclav (PO/IV)
- Trimethoprim (PO/IV [as Cotrimoxazole])
- Nitrofurantoin (PO)
- Gentamicin (IV)

Co-amoxiclav (It is second line)

61

When is second line treatment initiated in the treatment of UTIs?

If resistant to >=1 of the 1st line treatments

62

Which of the following is not a second line treatment of UTIs:
- Pivmecillinam (PO)
- Temocillin (IV)
- Cefalexin (PO)
- Ciprofloxacin (PO/IV)
- Vancomycin

Vancomycin

63

How many antibiotics are often tested for sensitivities?

12-20

64

Approximately how many antibiotics are reported back to doctors?

~4 (more if resistant)

65

Is amoxicillin safe in pregnancy?

Yes

66

What is amoxicillin useful for?

Enterococcus faecalis
Some coliforms:
- 50% of E. coli are now resistant
- Not great empirical treatment

67

How does Trimethoprim work?

Inhibits bacterial folic acid synthesis:
- Dihydrofolate -> Tetrahydrofolate
-> Dihydrofolate Reductase inhibited

68

When is Trimethoprim not safe in pregnancy and why?

1st trimester:
- Inhibits folic acid synthesis -> Spina bifida

69

Why is Trimethoprim recommended for UTI with prostatitis?

Good [urine] and [prostate]

70

What two antibiotics form PO/IV Co-trimoxazole?

Sulphamethoxazole + Trimethoprim

71

What is a serious side effect of using Co-trimoxazole?

Stevens-Johnson Syndrome

72

Which of the following is not reliably covered by Trimethoprim:
- Most coliforms
- Enterococci
- Staph aureus
- MRSA
- Proteus sp
- Pseudomonas

Proteus sp.
Pseudomonas

73

When is Nitrofurantoin useful? Why is it useful here?

In lower UTI:
- Effective [urine] only reached in bladder

74

Why should nitrofurantoin be avoided in late pregnancy?

Can cause neonatal haemolysis

75

When else should nitrofurantoin be avoided?

Breastfeeding
Kids

76

Which of the following is not covered by nitrofurantoin:
- Most coliforms
- Proteus sp.
- Enterococci
- Staph aureus
- MRSA
- Pseudomonas

Proteus sp.
Pseudomonas

77

Why must gentamicin be avoided?

Can affect:
- Hearing
- CN VIII
- Kidneys

78

What is the dose of gentamicin?

7mg/kg once daily IV

79

After giving a dose of gentamicin, what follow up is needed?

Measure blood levels 6-14hrs later

80

Which of the following is not covered by gentamicin:
- Most coliforms
- Pseudomonas sp.
- Staph aureus
- MRSA
- Enterococci

Enterococci

81

In what infection is gentamicin most useful in?

Gram negative sepsis

82

Gentamicin can only be prescribed for 3 days, this means 3 doses should be given. True or false?

False
(Eg. in CKD, a dose may be given every 36hrs ie. 2 doses in 3 days)

83

What is Pivmecillinam?

Esterified form of mecillinam

84

When is Pivmecillinam most useful?

Uncomplicated lower UTI

85

Why are pivmecillinam and temocillin active against ESBL-producing bacteria?

Very β-lactamase stable

86

What bacteria does Pivmecillinam not have activity against?

Gram positives
Pseudomonas

87

Is pivmecillinam safe in pregnancy?

No

88

When is temocillin useful?

If gentamicin can't be given:
- In urosepsis if renal function too poor

89

True or false, temocillin is just as effective as gentamicin?

False (it is less effective)

90

What bacteria does temocillin not have activity against?

Gram positives
Pseudomonas

91

What class of drugs does Cefalexin belong to?

1st generation oral cephalosporins

92

Is Cefalexin safe in pregnancy?

Yes

93

When is Cefalexin reported?

If amoxicillin and trimethoprim resistant

94

What are the risks of using Cefalexin?

Increased risk of C. diff
High risk of UTI recurrence

95

Which of the following bacteria does Cefalexin not cover:
- Most coliforms
- Enterococci
- Pseudomonas
- Staph aureus
- MRSA

Enterococci
Pseudomonas
MRSA

96

What are the benefits of using Co-Amoxiclav?

Cheap
Effective
Safe in pregnancy

97

What is the main disadvantage of using Co-Amoxiclav?

C. diff risk

98

Which of the following bacteria is not covered by Co-Amoxiclav:
- Most coliforms
- MRSA
- Staph. aureus
- Enterococci
- Pseudomonas

MRSA
Pseudomonas

99

How does Ciprofloxacin work?

Inhibits bacterial DNA gyrase:
- Prevents 'DNA' supercoiling

100

In what patients is Ciprofloxacin not safe? Whys is it not safe?

Kids
Pregnancy
- Damages cartilage

101

What bacteria is Ciprofloxacin useful against?

Pseudomonas (Only PO useful against Pseudomonas)
Almost all coliforms
Some Enterococci

102

What is the empirical treatment of female lower UTI?

Trimethoprim OR Nitrofurantoin:
- PO for 3 days

103

What is the empirical treatment of male, uncatheterised UTIs?

Trimethoprim OR Nitrofurantoin:
- PO for 7 days

104

What is the empirical GP treatment for complicated UTIs or pyelonephritis?

Co-amoxiclav OR Co-trimoxazole for 14 days

105

What is the empirical hospital treatment for complicated UTIs or pyelonephritis?

Amoxicillin (for Enterococci) AND Gentamicin IV (for coliforms) for 3 days

106

What is the empirical hospital treatment for complicated UTIs or pyelonephritis in a penicillin-allergic patient?

Co-trimoxazole AND Gentamicin

107

How many organisms are present on urine culture in asymptomatic bacteriuria?

>10^5 organisms/ml

108

How does asymptomatic bacteriuria appear on urine microscopy?

No pus cells

109

Why are antibiotics prescribed in pregnant women with asymptomatic bacteriuria?

To prevent:
- Pyelonephritis (20-30%)
- Intra-Uterine Growth Retardation (IUGR)
- Prematurity

110

What can cause an abacterial cystitis/urethral syndrome?

Early UTI
Urethral trauma ('Honeymoon cystitis')
Urethritis due to:
- Chlamydia
- Gonorrhoea

111

What are some features of abacterial cystitis?

Symptoms of UTI
Pus cells in urine
No significant growth on culture

112

How can symptoms be reduced in abacterial cystitis?

Alkalinising the urine

113

When should a UTI in catheterised patients be treated?

If >10^5 organisms/ml AND symptomatic

114

What can unnecessary antibiotics cause in catheterised patients?

Colonisation with resistant strains