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Management of Infection > Lecture 5 - Infection Control > Flashcards

Lecture 5 - Infection Control Flashcards

1
Q

What was the prevalence of HAI in scottish hospitals in 2016?

A

4.5%

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2
Q

What are the most common types of HAI?

A

urinary tract infections (24.5%)
respiratory infections (22.4%)
surgical site infections (16.5%)

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3
Q

What does each infection mean?

A

additional NHS costs, greater patient discomfort, and reduced patient safety

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4
Q

Cost of HAI?

A

> £1.6 billion/year in UK

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5
Q

How much could HAIs be reduced?

A

estimated ~30%

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6
Q

Escherichia coli bacteraemia?

A

E coli is most common pathogen causing bacteraemia

usually develops as a consequence of other infections

90 per 100,000 acute bed days

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7
Q

C. difficile infection?

A

usually causes diarrhoea and significant morbidity and mortality

develops as complication of other infections e.g. UTI

incidence of 2.8%

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8
Q

Surgical site infection?

A

when microorganisms get into the sterile area

causes significant morbidity and mortality

18.6% of all HAI

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9
Q

Urinary tract infection?

A

most common cause of HAIs

many associated with catheterisation

most common isolates are E. coli and K pneumoniae

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10
Q

Staph aureus infection?

A

When S. aureus breaches body defences it can cause a range of illnesses from minor skin infections to bacteraemia

32 per 100,000 acute bed days

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11
Q

What is the incidence of MRSA?

A

2.2 per 100,000 acute bed days

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12
Q

Norovirus?

A

highly infectious and spreads easily

no lasting immunity

causes significant morbidity and mortality
outbreaks result in ward closure and affects hospital work patterns

present in autumn/winter and causes vomiting and diarrhoea

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13
Q

HAI in ICU?

A

highest prevalence compared to other parts of hospital

critically ill patients have multiple co-morbidities and invasive procedures

2.5% incidence

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14
Q

Most common pathogens associated with HAI?

A

enterobacteriaceae (E. coli) 33%

staph aureus (20.2%)

clostridium difficile (5.3%)

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15
Q

What is a reservior?

A

a location where possible pathogens may live and multiply

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16
Q

Examples of a reservoir?

A

in or on a person or animal (host) (e.g. opportunistic pathogens)

in soil (e.g. C difficile)

in water (pseudomonas spp, legionella)

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17
Q

How can pathogens exit the reservoir?

A

ear (wax)

broken of infected skin (pus or blood)

skin (flakes)

anus (faeces)

eyes (tears)

nose (secretions)

mammary glands (milk, secretions in females)

vagina (secretions, blood)

urethra (urine)

seminal vesicles (semen and lubricating secretions)

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18
Q

How much skin does the body shed per day?

A

15g of skin per day, these can host up to 8-10 bacteria per skin square

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19
Q

What do nasal secretions indicate?

A

infected sinuses or respiratory infections

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20
Q

Direct contact transmission?

A

body surface to body surface between an infected individual and susceptible person

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21
Q

Example of direct contact transmitted infections?

A

influenza, chlamydia

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22
Q

Droplet contact transmission?

A

generated during coughing or sneezing

meningococcus spp, influenza, coronaviruses

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23
Q

Airborne transmission?

A

generation of aerosols (<5um) which are airborne and can spread considerable distances e.g. TB, varicella virus

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24
Q

Surface transmission?

A

infectious agent deposited onto an object or surface and survives long enough to transfer to another person who touches the surface

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25
Q

examples of surface transmission?

A

enterococcus spp, staph spp

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26
Q

Vehicle transmission?

A

usually a single contaminated source spreads infection

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27
Q

Example of vehicle transmission?

A

legionella outbreak in edinburgh 2012

4 deaths

pathogens grow in stagnant water, the vapour from this can then be inhaled

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28
Q

Vector borne transmission?

A

transmission by an insect or animal e.g. mosquitos, ticks etc

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29
Q

Droplet transmission?

A

transmitted when an infected person sneezes, talks or coughs

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30
Q

Pathogens transmitted via droplet transmission?

A

COVID-19

adenovirus

influenza B

measles

strep pyogenes

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31
Q

Infection control of droplet transmission?

A

Isolation of infected individual

use of PPE

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32
Q

How far can droplets travel?

A

larger droplets can travel around 1m

smaller droplets can remain entrained in air for much further distances

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33
Q

Toilet hygiene?

A

females > males
60% vs 40%

faecal matter may be retained on hands so handwashing is important

34
Q

What is airborne transmission?

A

residue from evaporated droplets or dust particles containing microorganisms remain suspended in the air

pathogens capable of surviving for long periods outside the body and are resistant to drying

transmission by inhalation

35
Q

Examples of pathogens transmitted by air?

A

mycobacterium tuberculosis, measles and varicella virus

36
Q

Portal of entry into the body?

A

broken skin

insect bites

anus

conjunctiva of eyes

nose

mouth

penis/vagina

37
Q

Examples of gram positive bacteria that can survive for months?

A 
gram pos 
S aureus (MRSA)
S pyogenes 
enterococcus species 
C difficile
38
Q

Examples of gram negative bacteria that can survive for months?

A

acinetobacter species
E. coli
P. aeruginosa
serratia marcescens

39
Q

Gram negative bacteria that can persist for days?

A

H influenzae
bordetella pertussis
proteus vulgaris
vibrio cholera

40
Q

Respiratory viruses that can persist for hours?

A

coronoviruses
coxsackie virus
influenza virus
SARS virus

41
Q

Blood borne viruses that can persist for more than a week?

A

HIV

hepatitis B

CMV

herpes simples (1&2)

42
Q

Fungal pathogens that can survive for many months?

A

candida albicans

43
Q

What is regular surface sanitisation critical for?

A

maintaining an environment which has as a low a population of pathogenic microorganisms present

this reduces potential transmission rates

44
Q

What are disinfectants used for?

A

to wipe high touch areas

shown to be more effective than cleansing agents

45
Q

What is needed to disinfection to be effective?

A

a high rate of compliance (>80%) to daily disinfect wipe down of the high touch points

46
Q

Why do small numbers of pathogens give a good chance of preventing infection?

A

there needs to be a large number of pathogens overwhelming the immune system to cause infection

47
Q

What can regular sanitisation reduce?

A

HAIs

MRSA
C difficile
vancomycin resistant enterococci

48
Q

Alcohol used as disinfectants?

A

ethanol

propanol

isopropyl alcohol

49
Q

What are alcohols active against?

A

vegetative forms of bacteria, fungi and coated viruses

50
Q

Contact time of alcohol?

A

limited due to rapid evaporation from surfaces limits antimicrobial activity

51
Q

Concentration of alcohol disinfectants?

A

70-90%v/v

52
Q

Why are alcohols not effective at higher concentrations?

A

needs water to participate in hydrogen bonding between the alcohol and the pathogen

53
Q

Chlorine based disinfectants?

A

most widely used disinfectants in hospitals and insutry

54
Q

What happens in chlorine solutions?

A

the hypochlorite (ClO-) ion is in equilibrium with hypochlorous acid, the chemical species responsible for antimicrobial activity

55
Q

Hypochlorous acid acitivity?

A

bactericidal, fungicidal, virucidal against both coated and uncoated viruses

56
Q

What is the antimicrobial activity of hypochlorous acid dependent on?

A

pH
pH > 9 the antimicrobial is lowest since the hypochloride ion predominates

pH < 7 hypochlorous acid predominates

57
Q

Concentrations of chlorine based disinfectants?

A

10,000ppm

10mcg/ml

58
Q

Use of chlorine based disinfectants in highly soiled areas?

A

concentration needs to be increased dramatically for cleaning vomit/urine/faece

59
Q

Iodinated disinfectants?

A

iodine has bactericidal, fungicidal, sporicidal and virucidal activity

60
Q

What does the activity of iodinated disnifectants lie with?

A

primarily resides with I2

61
Q

What is iodine used for?

A

used clinically as an iodophor product

iodine carrier or releasing agent

62
Q

Types of iodine disinfectants used?

A

povidone iodine (povidone is a complexing agent) (used in UK)

poloxamer iodine (poloxamer is a surfactant solubiliser)

63
Q

What are iodine disinfectants mainly used for?

A

skin disinfectants (pre-surgery) as they are less irritating than iodine tinctures

yellow colour shows areas that have been disinfected easily

64
Q

Peroxygens?

A

hydrogen peroxide (20-35%v/v) (H2O2)

peracetic acid (0.3%w/v) (CH3COOOH)

65
Q

What peroxygen is inactivated by organic matter?

A

hydrogen peroxide

66
Q

What are peroxygens used for?

A

bother are bactericidal, fungicidal, virucidal

peracetic acid is sporicidal

67
Q

What is the antimicrobial activity of peroxygens due to?

A

through generation of hydroxyl free radicals

68
Q

What are the 3 quaternary ammonium compounds (QAC) used as disinfectants?

A

benzalkonium chloride
cetrimide
cetylpyridinium chloride

69
Q

What do QACs do?

A

adsorb and penetrate the cytoplasmic membrane

this causes loss of membrane integrity and escape of intracellular contents

also causes loss of membrane bound enzyme function

70
Q

What are QAC always carrying?

A

a positive charge

they have a long lipophilic chain associated with the head group

71
Q

Concentrations of QAC?

A

1-20%

72
Q

What is a downside of QAC?

A

readily inactivated by organic matter so are not good for heavily soiled areas

73
Q

What factors place a person at risk of infection?

A

age (extremes)

immune status

genetics

current co-morbidities

nutritional status
(above all related)

behaviours

74
Q

What can the innate immune system be influenced by?

A

environment and nutritional state

75
Q

Potential interventions at individual level?

A

vaccination

clinical intervention to prevent diabetes (glucose control), COPD (smoking), malnutrition

76
Q

How to reduce the chance of disease transmission?

A

minimise disease exposure (isolation)

behavioural change (condoms)

enhance PPE (mask, gloves)

77
Q

What is hand-mediated transmission?

A

a major contributing factor in the acquisition and spread of infection in hospitals and community

78
Q

When to wash hands with soap?

A

when the hands are visibly soiled or potentially contaminated by biological fluids

when interacting with patients with vomiting or diarrhoea

79
Q

When to use alcohol based hand rubs?

A

before/after direct contact even if wearing gloves

80
Q

What are alcohol based hand rubs not effective against?

A

C difficile

81
Q

What % of vaccination is needed for heard immunity?

A

> 95%

Management of Infection (36 decks)

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