Infectious Diseases

Question 1

What antibiotic therapy is recommended for sepsis of unknown location

Answer 1

IV Amox, Met, Gent

If penicillin allergic use vancomycin instead of amox

Question 2

Why would you switch a patient from gentamicin to azetreonam

Answer 2

If they have been on gent for 72 hours but still require therapy
If they have renal impairment

Question 3

Metronidazole covers which type of bacteria

Answer 3

Anaerobes

Question 4

What are some of the complications of using peripheral venous catheters

Answer 4

Insertion site phlebitis and catheter related blood stream infection

Question 5

Explain the formation of biofilms on peripheral vascular catheters

Answer 5

A sheath of biological material can form on the PVC
Microorganisms can adhere to this biofilm and some such as S.aureus contribute
This biofilm can protect microorganisms from the effect of antibiotics
If left in long enough, parts of the biofilm can break off and spread through the blood leading to infection

Question 6

What should be done to prevent contamination of the blood culture bottle itself

Answer 6

Remove the cap and decontaminate the rubber stopper with an alcohol wipe
Ensure the fluid in the bottle is not orange/red as this indicates prior contamination - get a new bottle

Question 7

What is the optimum blood volume taken for a blood culture

Answer 7

8-10ml per botthle

No more than 1% of blood volumes for infants and children

Question 8

What is the risk of overfilling a blood culture bottle

Answer 8

Can lead to false positives

CO2 generated by the excess WBC can trigger the detectors indicating a false positive

Question 9

Which sites should be avoided for blood culture samples

Answer 9

Femoral vein - hard to adequately clean area
Existing peripheral cannulae - may be colonised
Central venous access devices - unless it is the device that is infected
Arteriovenous shunt - do not cannulate the affected arm/hand

Question 10

Which blood culture bottle should be filled first

Answer 10

The aerobic one

Reduces chance of air contamination in the anaerobic one

Question 11

What is the main causative organism of UTIs

Answer 11

E.coli

Question 12

List risk factors for catheter associated UTI

Answer 12

Female 
Elderly 
Impaired immune system 
History of catheter use 
The length of time it is in situ 
Length of hospital stay prior to insertion 
Previous UTI/CAUTI

Question 13

What is an Arteriovenous fistula

Answer 13

A subcutaneous anastamosis of an artery and adjacent vein - usually wrist radiocephalic or elbow brachiocephalic
It is used for long lasting, permanent vascular access
E.g. in dialysis patients

Question 14

What is the purpose of an AVF

Answer 14

It causes more blood to flow into the vein (as now connected directly to the artery)
This makes it larger and stronger and so improves the site for repeated needle insertions

Question 15

What is an arteriovenous graft

Answer 15

A synthetic tube graft is used to connect an artery and vein - this becomes the site of needle placement
Used if the patient doesn’t have a suitable vein for fistula creation

Question 16

Which patient factors increase the risk of severe infection

Answer 16

Severe underlying disease 
Severe malnourishment 
Immunosuppression or immunodeficiency 
Loss of skin integrity - i.e. trauma 
Pre-existing infection near or at insertion site

Question 17

How does a AVF/AVG infection present

Answer 17

Local signs - redness, swelling, pain, general inflammation

Systemic infection signs

Question 18

How long does it take an AV fistula to mature before it can be used

Answer 18

4-8 weeks

Question 19

C.diff will always cause symptoms if present - true or false

Answer 19

False
Present in the bowel of up to 3% of the healthy population and can live in the bowel without causing harm (asymptomatic colonisation)

Question 20

C.diff produces spores - true or false

Answer 20

True

Question 21

Which antibiotics are most frequently associated with a C.diff infection

Answer 21

Clindamycin
Cephalosporins
Ciprofloxacin (fluoroquinolones)
Co-amoxiclav (broad spectrum penicillins)

Question 22

What is the main risk factor for C.diff infection

Answer 22

Previous exposure to antibiotics

Question 23

How does C.diff infection present

Answer 23

It is a GI infection
Symptoms range from mild diarrhoea to life threatening colitis
Also abdominal cramps, fever, raised WCC
Can be fatal - peritonitis, toxic megacolon etc.

Question 24

How do patients aquire C.diff infection

Answer 24

Receive antibiotic or enteral therapy
This alters the micro flora in the gut
Patients are exposed to C.diff and become colonised
C.diff mulitplies and releases toxins leading to infection

Question 25

What are the risk factors for a C.diff infection

Answer 25

``` Current or recent (last 3 months) used of antibiotics Increased age (>65) Prolonged inpatient stay Serious underlying disease Surgical procedures Immunosuppression Use of PPIs Previous C.diff infection ```

Question 26

How long after antibiotic treatment is started does C.diff infection typically present

Answer 26

Symptoms usually present between day 4-9 of treatment | However, they can occur up to 8 weeks after discontinuation of treatment

Question 27

What is the definition of diarrhoea

Answer 27

The passage of 3 or more loose or liquid stools per day | Or more frequently if 3 is normal for the patient

Question 28

How does C.diff spread

Answer 28

It is spread via spores which C.diff releases Can be ingested from environment, contaminated surfaces, hands of staff or visitors Symptomatic patients shed these spores in their stool at a high rate - main source of contamination in hospital

Question 29

What is the main route of transmission of C.diff

Answer 29

Faecal oral route | Contact with an infected person or contaminated surface and then touching your mouth

Question 30

How do you treat C.diff infection

Answer 30

Oral metronidazole - mild Oral Vancomycin - severe Start treatment as soon as suspected - don't wait for the lab

Question 31

C.diff infections can recur - true or false

Answer 31

True | Either via reinfection from a contaminated environment or relapse from ggerminatingspores in the gut

Question 32

C.diff patients should be isolated - true or false

Answer 32

True If symptomatic they need to be isolated and contact precautions put in place Give an ensuite or commode to prevent toilet contamination and spread Isolated until 48 hours symptom free

Question 33

Alcohol hand gel is sufficient when contacting a C.diff patient - true or false

Answer 33

FALSE Must use warm water and soap Gel does not kill or get rid of the spores

Question 34

When is a patient considered to be clear of a C.diff infection

Answer 34

When they have been asymptomatic (e.g. no diarrhea) for 48 hours You do not need to send samples to the lab to confirm clearance

Question 35

What are the requirements for IV antibiotics to oral switch (IVOST)

Answer 35

Haemodynamically stable - BP/HR normalising and apyrexial for >24 hours Oral route available - eating/drinking and no malabsorption Infection markers improving - WCC moving towards normal Excluded deep seated infection source.