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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
examples of surface transmission?
enterococcus spp, staph spp
26
Vehicle transmission?
usually a single contaminated source spreads infection
27
Example of vehicle transmission?
legionella outbreak in edinburgh 2012 4 deaths pathogens grow in stagnant water, the vapour from this can then be inhaled
28
Vector borne transmission?
transmission by an insect or animal e.g. mosquitos, ticks etc
29
Droplet transmission?
transmitted when an infected person sneezes, talks or coughs
30
Pathogens transmitted via droplet transmission?
COVID-19 adenovirus influenza B measles strep pyogenes
31
Infection control of droplet transmission?
Isolation of infected individual use of PPE
32
How far can droplets travel?
larger droplets can travel around 1m smaller droplets can remain entrained in air for much further distances
33
Toilet hygiene?
females > males 60% vs 40% faecal matter may be retained on hands so handwashing is important
34
What is airborne transmission?
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
Examples of pathogens transmitted by air?
mycobacterium tuberculosis, measles and varicella virus
36
Portal of entry into the body?
broken skin insect bites anus conjunctiva of eyes nose mouth penis/vagina
37
Examples of gram positive bacteria that can survive for months?
``` gram pos S aureus (MRSA) S pyogenes enterococcus species C difficile ```
38
Examples of gram negative bacteria that can survive for months?
acinetobacter species E. coli P. aeruginosa serratia marcescens
39
Gram negative bacteria that can persist for days?
H influenzae bordetella pertussis proteus vulgaris vibrio cholera
40
Respiratory viruses that can persist for hours?
coronoviruses coxsackie virus influenza virus SARS virus
41
Blood borne viruses that can persist for more than a week?
HIV hepatitis B CMV herpes simples (1&2)
42
Fungal pathogens that can survive for many months?
candida albicans
43
What is regular surface sanitisation critical for?
maintaining an environment which has as a low a population of pathogenic microorganisms present this reduces potential transmission rates
44
What are disinfectants used for?
to wipe high touch areas shown to be more effective than cleansing agents
45
What is needed to disinfection to be effective?
a high rate of compliance (>80%) to daily disinfect wipe down of the high touch points
46
Why do small numbers of pathogens give a good chance of preventing infection?
there needs to be a large number of pathogens overwhelming the immune system to cause infection
47
What can regular sanitisation reduce?
HAIs MRSA C difficile vancomycin resistant enterococci
48
Alcohol used as disinfectants?
ethanol propanol isopropyl alcohol
49
What are alcohols active against?
vegetative forms of bacteria, fungi and coated viruses
50
Contact time of alcohol?
limited due to rapid evaporation from surfaces limits antimicrobial activity
51
Concentration of alcohol disinfectants?
70-90%v/v
52
Why are alcohols not effective at higher concentrations?
needs water to participate in hydrogen bonding between the alcohol and the pathogen
53
Chlorine based disinfectants?
most widely used disinfectants in hospitals and insutry
54
What happens in chlorine solutions?
the hypochlorite (ClO-) ion is in equilibrium with hypochlorous acid, the chemical species responsible for antimicrobial activity
55
Hypochlorous acid acitivity?
bactericidal, fungicidal, virucidal against both coated and uncoated viruses
56
What is the antimicrobial activity of hypochlorous acid dependent on?
pH pH > 9 the antimicrobial is lowest since the hypochloride ion predominates pH < 7 hypochlorous acid predominates
57
Concentrations of chlorine based disinfectants?
10,000ppm | 10mcg/ml
58
Use of chlorine based disinfectants in highly soiled areas?
concentration needs to be increased dramatically for cleaning vomit/urine/faece
59
Iodinated disinfectants?
iodine has bactericidal, fungicidal, sporicidal and virucidal activity
60
What does the activity of iodinated disnifectants lie with?
primarily resides with I2
61
What is iodine used for?
used clinically as an iodophor product | iodine carrier or releasing agent
62
Types of iodine disinfectants used?
povidone iodine (povidone is a complexing agent) (used in UK) poloxamer iodine (poloxamer is a surfactant solubiliser)
63
What are iodine disinfectants mainly used for?
skin disinfectants (pre-surgery) as they are less irritating than iodine tinctures yellow colour shows areas that have been disinfected easily
64
Peroxygens?
hydrogen peroxide (20-35%v/v) (H2O2) peracetic acid (0.3%w/v) (CH3COOOH)
65
What peroxygen is inactivated by organic matter?
hydrogen peroxide
66
What are peroxygens used for?
bother are bactericidal, fungicidal, virucidal peracetic acid is sporicidal
67
What is the antimicrobial activity of peroxygens due to?
through generation of hydroxyl free radicals
68
What are the 3 quaternary ammonium compounds (QAC) used as disinfectants?
benzalkonium chloride cetrimide cetylpyridinium chloride
69
What do QACs do?
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
What are QAC always carrying?
a positive charge they have a long lipophilic chain associated with the head group
71
Concentrations of QAC?
1-20%
72
What is a downside of QAC?
readily inactivated by organic matter so are not good for heavily soiled areas
73
What factors place a person at risk of infection?
age (extremes) immune status genetics current co-morbidities nutritional status (above all related) behaviours
74
What can the innate immune system be influenced by?
environment and nutritional state
75
Potential interventions at individual level?
vaccination clinical intervention to prevent diabetes (glucose control), COPD (smoking), malnutrition
76
How to reduce the chance of disease transmission?
minimise disease exposure (isolation) behavioural change (condoms) enhance PPE (mask, gloves)
77
What is hand-mediated transmission?
a major contributing factor in the acquisition and spread of infection in hospitals and community
78
When to wash hands with soap?
when the hands are visibly soiled or potentially contaminated by biological fluids when interacting with patients with vomiting or diarrhoea
79
When to use alcohol based hand rubs?
before/after direct contact even if wearing gloves
80
What are alcohol based hand rubs not effective against?
C difficile
81
What % of vaccination is needed for heard immunity?
>95%

Management of Infection (36 decks)

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