Lecture 7 - Infection control

Question 1

Define:

1) carrier
2) colonisation
3) infection

Answer 1

1) person who has microbes with no sign of disease
2) presence and multiplication of microbes without tissue invasion or damage
3) entry and multiplication into tissue causing damage

Question 2

Define:

1) contamination

2) reservoir

Answer 2

1) soiling of objects with potential infectious material

2) place where micro-organism lives and reproduces

Question 3

What is the difference between exogenous and endogenous infection with examples of both

Answer 3

• exogenous means from another person or environment: e.g. airborne, contact or percutaneous
• endogenous means self infection e.g. surgical wound

Question 4

Give examples of Airborne transmission

Answer 4

droplets - TB flu.
fluids - nebulisers.
dust - aspergillius.

Question 5

Give examples of contact transmission

Answer 5

hands - MRSA
body fluids - HIV Hep
equipment - pseudo TB
food - salmonella campylobac

Question 6

Give examples of percutaneous infection

Answer 6

Insect vectors - malaria
intravascular lines - s aureus
contaminated IV fluid - gram neg bacilli
sharps injuries - Hep B HIV

Question 7

Give an example of self infection

Answer 7

picking at a wound - s aureus

Question 8

Name some host factors which increase susceptibility to infection

Answer 8

• any compromises in normal defences e..g break in skin
• diabetes
• immunosuppression
• iv or urinary catheters
• prolonged hospital stay
• recurrent admissions
• intensive care
• prolonged broad spec ABs (pre disposed to infection MDR)

Question 9

define a nosocomial infection

Answer 9

more than 48h post admission
under 10 days of discharge (30 for surgical wound )
within 72h of outpatient procedure

Question 10

name the 5 most common type of nosocomial infection

Answer 10

UTI
Resp infections post op
surgical wound
line infections / other devices
diarrhoea (viral GE or C diff)

Question 11

What indicates a line infection

Answer 11

phlebitis, painful venflon site and pus on removal

Question 12

Common causes of line infections

Answer 12

Gram negative bac (MDR)
MRSA
C diff
Haemtolytic strep
VRE

Question 13

1) Which antimicrobials are coliforms showing increased resistance of
2) give 2 examples of coliforms
3) how does this resistance occur

Answer 13

1) beta lactams
2) klebsiella or e.coli
3) enzymes with beta lactam resistance e.g. ESBA ampC

Question 14

Which Abx was usually last line however recently has huge worldwide concern of emerging MDR + which to ABs may work

Answer 14

carbapenems

tigecycline and IV colistin

Question 15

Name two ways hospital can prevent multi drug resistance

Answer 15

1 -remove exogenous sources (sterile equipment and good hygine etc)
2 -block transmission ( protective clothing and hand washing and isolation)

Question 16

When does Group A streptococcus cause hosp acquired infections? How is it spread?

Answer 16

1) post op infection or post natal sepsis.

2) staff or visitors may introduce usually contact transmission though droplets may aerosolise

Question 17

List 6 ways infection control can improve host resistance to bacteria following surgery

Answer 17

good nutrition
immunisation
good surgical technique
minimise use of invasive devices
appropriate use of antibiotics
education

Question 18

Name 3 occasions where antibiotics shouldn’t be prescribed following positive culture results

Answer 18

• asymptomatic bacteruria (unless pregs)
• long term catheter almost always colonised only treat if evidence systemic
• wounds often colonised only treat if evidence infection (cellulitis worsening pain)

Question 19

What other infec control methods can be put in place if a MDR strain is found?

Answer 19

isolation in single room and microbiological screening, no unneccessary movement of patient, terminal cleaning,