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Flashcards in Infection And Immunity Workshops Deck (95):
0

What's the difference between polyenes and polymixins?

Polymixins work in bacteria (antibiotic)
Polyenes work in fungi (antifungal)
Both Work on cell membranes/ outer membrane

1

Where do polymixins work? How do they work?

Only work on gram negative bacterias Outer membrane
Work on LPS
They bind to the lipid A component of LPS
They increases the outermembranes permeability

May also interact with the cytoplasmic, inner membrane
Interact with phospholipids here and increase permeability

2

How could a bacteria become resistant to polymixin antibiotics ?

A change in the LPS of the bacteria (in the lipid A component) results in polymyxins being unable to bind.
This resistance is quite rare

3

Where in a bacteria does chloramphenicol act?

Bacterial ribosomes
It binds to the 50S subunit and decreases peptide bond formation between amino acids so inhibits bacteria protein synthesis

4

How could a bacteria become resistant to chloramphenicol?

Through CAT genes
Chloramphenicol Acyl transferase genes
This enzyme will inactivate chloramphenicol

5

What antibiotic targets the nucleoid in bacterial cells?

Trimethoprim

6

How does trimethoprim work?

Works in the nucleus
It inhibits dihydrofolate reductase enzyme
This enzyme is needed to convert dihydrofolic acid into trihydrofolate, and trihydrofolic acid is needed to make bases in the bacteria. So it stops bacterial DNA being formed.

7

How could a bacteria become resistant to trimethoprim?

Alterations in dihydrofolate reductase enzyme so that trimethoprim can no longer bind
Also alterations in the uptake of the antibiotic into the bacteria

8

Glycopeptides act at the cell wall of bacteria. How do they work?

Bind to the d-ala d-ala sequence
Therefore inhibit binding of more monomers to the peptidoglycan chains; stop these stop these from Crosslinking so decrease stability in the cell wall of bacteria

9

How could a bacteria become resistant to glycopeptides?

Mutation in d-ala d-ala becoming d-ala d-lactate
Glycopeptides can no longer bind

This mutation is common in Enterococci

10

What bacteria cause catheter associated UTIs? Which is most common?

E.coli (most common)
Enterococcus faecilis (quite common)
Both these are from the gut
Staph epidermis, staph aureus (quite common)
Psudomonas
Klebsiella
Proteus

11

What do we use to treat catheter associated UTIs?

All the bacteria that cause this are a mixture of gram positive and negative. Therefore need to treat with broad spectrum antibiotics.
IV antibiotics used:
Gentamicin (1st choice) + amoxicillin and Coamoxiclav to fight resistant bacteria
Or
Vancomycin
Ciprofloxacin

12

What TYPICAL agents cause community aquired pneumonia?

Streptococcus pneumoniae
Haemophillus influenza
Streptococcus pyogenes

13

What ATYPICAL agents may cause intracellular infections?

Legionella pneumophila
Mycoplasma pneumonia
Chlamydia pneumonia

Cause intracellular infections so need to choose antibiotics that GET into cells

14

What Do we use to treat community aquired pneumonia?

Amoxicillin/ co-amoxiclav orally

Or if patient is allergic to penicillin: Clarithromycin
Doxycycline

15

What is Cellulits?

Inflammation of the skin
May occur from an insect bite
Or an operation opening up the skin

Could get in the blood stream and affect the heart: endocarditic Cellulitis

16

What organisms cause cellulitis?

Staph aureus
Streptococcus pyogenes
Staph epidermis
(Remember it's the staphs and streps: common on the skin!!)

17

What do we use to treat cellulitis ?

Flucloxacillin (oral/ IV)
Vancomycin (IV)

Could maybe chose Clarithromycin or doxycycline or penicillin V

18

What microorganisms can cause acute exacerbations in COPD?

Haemophilus influenzae
Streptoccocus pneumonia
Staph aureus

Remember it's the ones you'd expect in the lungs: influenzae and pneumonia

19

What can we use to treat COPD?

Doxycycline good as it works against all three

Amoxicillin (if you suspect resistance then give co-amoxiclav which contains a beta lactamase inhibitor)

Clarithromycin

20

Meningitis is the inflammation of the membranes lining the brain and spinal chord. It is rarely caused by bacteria, but when it does, what happens if you don't treat it rapidly with antibiotics?

Death

21

Where do bacteria invade in meningitis?

It is inflammation of the membranes lining the brain and spinal cord
They invade the back of the throat, pass into the blood stream and invade the CSF

22

Bacteria that cause meningitis live in the back of the nose and throat in 1/10 people.

But most people who carry these bacteria become immune to them so they don't usually cause disease.
The germs can be spread by secretions from nose and throat. But must have had close contact with the person or occasionally passed through respiratory droplets

23

Symptoms of meningitis occur suddenly after an incubation period of ______ days

1-3 days

24

What does the rash look like that's associated with meningitis?

Rash of tiny red/ purple pin prick spots
May spread to look like fresh burning
If you press on the rash- it doesn't go away!!

It's a result from bleeding capillaries close to the surface, as bacteria release toxins in the blood which break down blood vessel walls

25

What is meningococcal septicaemia?

Blood poisoning
Occurs when bacteria in the blood multiply uncontrollably

Meningococcal disease can appear as meningococcal meningitis or meningococcal septicaemia
Or a combination of both of these

26

What will very severe cases of meningitis go on to cause?

Hearing loss
Damage to the brain
Learning impairments
Epilepsy

What can septicemia cause in the long run?
Scarring to skin
Amputations

27

What is first line treatment if bacterial meningitis is suspected?

High dose benzyl penicillin IV


Or a high dose 3rd generation cephalosporin such as ceftriaxone (IV) or cefotaxime (IV)

28

What shall I use to treat meningitis if my patient has anaphylaxis with penicillins or rash with cephalosporins?

IV chloramphenicol 12.5mg/kg QDS

29

Why is benzyl penicillium a good first line treatment for bacterial meningitis?

It has a broad spectrum
Rapidly absorbed into blood stream
Non toxic at high concentration
Good penetration into CSF

This is the same for cephalosporins

30

What is the most common bacteria causing meningitis?

Neisseria meningitidis (meningococcal meningitis) most common
Type B accounts for most cases
Mostly in under 5 years olds or 15-24s
It's a gram negative bacteria so uses LPS LIpid A which is very toxic so can cause septic shock

31

What other bacteria can cause meningitis?

Streptococcus pneumonia (2nd most common)
In under 2s and over 65s and immunocompromised
It's the most dangerous type: 20% mortality whereas N.menigtiis is 10%

Haemophilus influenza B in under 5s

Less common:
Staph aureus
Listeria monocytogenes
Mycobacterium tuberculosis
E.coli

32

What antibiotic can we use for N.meningitis?

Penicillin G or ampicillin
Or if penicillin resistant: use 3rd generation cephalosporin like ceftriaxone or cefotaxime

Sensitive to both these: then chloramphenicol

33

What can we treat strep pneumonia bacterial meningitis with?

Ceftriaxone or cefotaxime IV
If penicillin resistant or pneumonococci suspected add in rifampicin or vancomycin

34

Sometimes with bacterial meningitis, relatives should be treated as prophylaxis. What can be given as prophylaxis for N.meningitis?

Rifampicin
Or ciprofloxacin

These are different to the actual treatments as we want to decrease chance of resistance

35

What prophylaxis can be used for bacteria caused by s. Pneumoniae?

No prophylaxis

36

What prophylaxis should be given for haemophilus influzae meningitis?

If patient lives with unvaccinated child under 4, the entire household should be given Rifampicin as prophylaxis

37

What vaccines are available for meningitis?

HiB vaccine (H. Influenzae type B)
N.meningitidis Type C (Men C)
N. Meningitidis type A, C, Y, W135
N. Meningitidis type B
S.pneumonia vaccines

38

What are the S.pneumonia vaccines?

Polysaccharide vaccine (PPV)
Not used in under 2s
Good for over 65s
Pneumonococcal Conjugate Vaccine (PCV)
Given IM. At 2,4 and 13 months old

39

You can also get viral meningitis. Is this as bad as bacterial?

No!
A lot more common
Slower onset
Less severe
No rash
Lasts up to 3 weeks
Self limiting: no real treatment, just get better yourself

40

Why do viruses produce less of an inflammatory response than bacteria?

Because viruses are usually present inside cells
Not visible to phagocytic macrophages
Macrophages aren't activated to same extent
Less inflammatory cytokines produced
May be released into the blood but they rapidly reinfect other cells so are hidden again!

41

What viruses may cause meningitis?

Enteroviruses
Such as
coxsackie virus (most common) found in intestines and faeces/ sewage
Echovirus

42

Meningitis may also sometimes be caused by fungus. Examples?

This is VERY rare
Candidia albicans - espesh in babies of very low birth weight

Cryptococcus neoformans: causes of most fungal meningitis
Normally only develops in people with deficient immune systems
Treat with amphotericin B, fluticytosine and fluconazole

Histoplasma: can cause meningitis is immuno-deficient patients

43

One of the adverse effects of methotrexate, taken in RA, is stomatitis and mouth ulceration.
1) how often do RA patients usually take methotrexate?
2) what can be given to prevent the serious adverse effects of methotrexate?

Methotrexate taken WEEKLY

Folic acid used at an agreed time before or after the weekly methotrexate dose.

44

Why does methotrexate have general toxicity?

Because it effects all rapidly dividing cells

45

What is the tuberculosis vaccine commonly given?

BCG vaccine
Consider in under 35s going to live or work in endemic areas
Administer after negative Mantoux test (6 pricks in wrist)

46

What's the vaccine commonly given for Hep A?

Monovalent vaccine (Havrix)
Hep A Is spread by faecal oral route. Eg shellfish

47

How is hep B spread? What is the vaccine usually given?

Exposure to infected blood or body fluids
Energix B usually given
Can take up to 6 months to reach immunity

48

What's the vaccine against meningitis ?

Meningitis A and C combines vaccine
Rapid immunity provided, long lasting: boosters given every 5 years if at continued risk

49

How many vaccinations of tetanus is considered to give life long immunity?

5

50

What is rabies?

Viral encephalomyelitits caused by members if the lyssavirus genus

Usually fatal

By bites and scratches from animals

51

What is tick-borne encephalitis?

Caused by the flavivirus carried by ticks or unpasteurised milk

Vaccinate anyone going to warm forested areas
Remove ticks ASAP with straight tweezers

52

When is the typhoid vaccination advised?

For areas where sanitation standards may be poor

53

What's the typhoid vaccine?

Live attenuated oral vaccine (Ty21a)
Give 3 doses on alternate days
Give at least 3 days before starting malaria prophylaxis
Avoid antibacterials 3 days before and after
3,3,3!!

54

When to give yellow fever vaccine?

Vaccinate those travelling to endemic areas at least 10 days before travel
10 years immunity

55

What vaccines are recommended for those travelling to Egypt?

Hep A, hep B
Rabies
Tetanus
Typhoid

56

What's the ABCD of malaria prophylaxis?

Awareness
Bite protection
Chemoprophylaxis
Diagnosis

57

What the first line prophylaxis of malaria?

Chloroquine (or proguanil)

58

What's second and third line prophylaxis of malaria?

Second line: chloroquine PLUS proguanil

Third line: mefloquine Or doxycycline or malarone

59

What is mefloquine contraindicated in?

Epilepsy

It has some serious CNS side effects like hallucinations

60

What's a good insect repellent to use?

Diethyltoluamide (DEET) 50%
Apply every 4 hours

61

Is malaria prophylaxis required for Egypt?

No risk currently
Beaut precautions essential

62

What are some of the possible bacterial causes of diahorrea?

Salmonella
Shigella
Campylobacter
E. coli
C. Difficile

63

What Protozoa may cause diahorrea?

Giardia
Cryptosporidium
Entamoeba histolytica

64

Whats the incubation period of giardia? What do we treat it with?

5- 25 days
Treat with metronidazole

65

What's the incubation period of c.difficile and what can we treat it with?

A few days
Metronidazole and vancomycin

66

What's the incubation period of campylobacter? What can we treat it with?

2-11 days
Erythromycin

67

Hepatitis C is a single stranded RNA virus belonging to the Flaivirdae family.
It can take up to ___ months to develop antibodies post infection

3 months

68

How is hepatitis C spread?

Through bodily fluids
So those most at risk are those who share needles or are exposed to infected blood

69

Why may people who received blood transfusions before 1991 still be at risk of developing hepatitis C?

It can lie dormant for 30-40 years

70

There are two forms of chronic hepatitis, chronic persistent and chronic active. What's the difference?

Chronic persistent: minimal degree of inflammation
Follows a benign course
You become an active carrier: I,e you're infective to others

Chronic active: continual destruction of hepatocytes
People become ill with liver disease

71

What's the course of illness with hepatitis C?

Acute infection- can be cured
But then further hepatocyte damage could lead to fibrosis , cirrhosis of the liver and cancer of the liver

72

Lichen planus
Rhumatoid arthritis
Cryoglobulinaemic Vasculitis
Sjögren's syndrome (dry eyes and mouth)
Are all what?

Extra manifestations of hepatitis C

73

Hep C: Genotype 1, 4, 5 ,6 usually classed together

Genotypes 2, 3 usually classed together

74

Which forms of hepatitis are you more at risk of getting when travelling?

Hepatitis A and B
So get vaccines!

75

Treating hepatitis C: how do we reduce the viral load?

Using interferon (peginterferon alpha) use in combo with
Ribavirin
Or protease inhibitors

Standard is 48 weeks of treatment

76

What's a common side effect with peginterferon?

Depression

77

What combination therapy may we use for hepatitis C?

Peg interferon in combo with ribavirin

This will decrease mortality
But increase risks of adverse effects

78

We have seen protease inhibitors crop up twice so far in this course. What two viruses are they against?

HIV
Hepatitis C

79

Why may glucocorticoids be used in Hep C?

To treat the underlying disorders such as rheumatoid arthritis and sjorgrens syndrome

80

What types of typhoid vaccines are there?

Vi vaccine: SINGLE INJECTION for over 2 years old.
Ty21a: 3 capsules to take on alternate days. Not for under 6's
Combined typhoid and HEP A vaccines for over 15 yr olds

81

Which is the most effective typhoid vaccine?

Vi vaccine generally more effective
Lasts around 3 years then need a booster

Ty21a lasts around 1 year

Ideally these should be given around 1 month before travel

82

Malarone is licensed as a malaria vaccine for trips lasting up to _______

28 days

83

Do not use doxycycline (malaria prophylaxis) in....?

Under 12 years or pregnancy !!

84

Which malaria prevention is safe in pregnancy ?

Chloroquine

Also proguanil

85

What's the deal with mefloquine as malaria prevention?

If it's not been used before, use 3 weeks before travel to detect for side effects (CNS side effects like bad dreams) then there's time for adjustment.
Don't use in depression or schizophrenia
Not licensed in Britain for use for over 1 year

86

What is miliara rubra?

Prickly heat

87

Where should insulin be kept on planes?

It will freeze and denature in the hold
So should be kept with you with all other medicines

88

What can cause travellers diahorrea?

E. coli
Salmonella
Parasites such as Giardia
Viruses such as norovirus

89

When should we not treat travellers diahorrea with eg Loperimide?

In under 2s
If there's blood or mucus in the stool
High fever
Severe abdominal pain

90

What antibiotics can we use to treat travellers diahorrea?

Ciprofloxacin
Azithromycin
Rifaximin

91

What antibiotics can we use to prevent travellers diahorrea?

Ciprofloxacin
Rifaximin

92

What can bismuth subsalicylate be used for?

A non-antibiotic prophylaxis of travellers diahorrea
Can cause blackening of the stool or tongue
Don't use for over 3,weeks

93

What's giardiasis caused by?

Giardia lamblia or giardia duodenalis

94

What's the incubation period of guardiasis?

9-15 days
So diahorrea may not start for a couple of weeks from when the traveller returns

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