Introduction to Infection Flashcards

1
Q

What is an infection?

A

An invasion of a host’s tissue by micro-organisms

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2
Q

What is disease caused by?

A
  • Microbial multiplication
  • Toxins
  • Host response
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3
Q

What is the importance of the host response causing a lot of damage?

A

When looking at managing patients, need to take into account what the host is doing

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4
Q

How can people get infections?

A
  • Directly from source
  • Through an intermediary
  • From the environment
  • From animals
  • Themselves
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5
Q

Give an example of an intermediary that can cause disease

A

Mosquito

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6
Q

What environmental sources are there of disease?

A
  • Water
  • Food
  • Air
  • Surfaces
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7
Q

What is the importance of disease transmitted through water?

A

Many young children killed by diarrhoea every year, mostly as a result of ingesting contaminated water

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8
Q

What diseases are particularly caused by ingested of contaminated food?

A

Gastroenteritis

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9
Q

How can air transmit disease?

A

If it is contaminated by environmental organisms

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10
Q

Give an example of a surface that can become contaminated by pathogens

A

Medical devices

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11
Q

What is the importance of the contamination of medical devices?

A

Potentially very important/dangerous infections, e.g. viral hepatitis, HIV

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12
Q

What is it called when a disease is transmitted by an animal?

A

Zoonosis

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13
Q

How can animals get infections?

A

From the environment, or infect the environment which then infects the patient

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14
Q

How can a person get an infection from themselves?

A

Organisms that the patient has in one place can spread to another place

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15
Q

What is meant by microbiota?

A

An ecological collection of microorganisms that are carried on the skin and mucosal surfaces

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16
Q

Are microbiota harmful?

A

They are normally harmless, or even beneficial, but can be harmful if they transfer to other sites

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17
Q

Give an example of where transfer of the microbiota can cause disease?

A

E. Coli from the large bowel getting into the urinary tract can use a UTI

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18
Q

What is true of many organisms considered to be pathogenic?

A

Many organisms considered to be pathogenic are only so when they’re in the wrong place

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19
Q

What is meant by microbiome?

A

It is a description of the entire ecosystem, including the host

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20
Q

Give an example of a group of infections that require physical contact for transmission

A

Sexually transmitted infections

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21
Q

Give an example of an infection where airborne spread is sufficient for transmission

A

Chickenpox

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22
Q

What are aerosols?

A

Small particles that can suspend in air

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23
Q

What do aerosols allow?

A

Air can remain infectious from some hours after someone infected has been in a room

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24
Q

Give an example of an infection where a vector is required for spread

A

Malaria

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25
Q

What are the modes of horizontal transport?

A
  • Contact
  • Inhalation
  • Ingestion
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26
Q

What kinds of contact can transmit infection?

A
  • Direct
  • Indirect
  • Vectors
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27
Q

What can be inhaled to spread infection?

A
  • Droplets
  • Aerosol
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28
Q

What kind of transmission is common through ingestion?

A

Faecal-oral transmission

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29
Q

What are the modes of vertical transmission?

A

Mother to child

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30
Q

When can infection be spread from mother to child?

A

Before or after birth

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31
Q

Give an example of an infection that be transmitted mother to child?

A

HIV

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32
Q

By what process do microorganisms cause disease?

A
  1. Exposure
  2. Adherence
  3. Invasion
  4. Multiplication
  5. Dissemination
33
Q

What types of pathogens invade?

A

All viruses, some bacteria

34
Q

How are pathogens disseminated?

A

Either by continous spread, or other ways, such as the haemotaginous route

35
Q

What is meant by continous spread?

A

Spreading locally

36
Q

What is meant by haemotaginous spread?

A

Spread in the blood

37
Q

What does the mechanism of dissemination determine?

A

Other aspects of the disease

38
Q

What are the determinants of disease?

A
  • Pathogen
  • Patient
39
Q

What pathogen factors determine disease?

A
  • Virulence factors
  • Inoculum size
  • Antimicrobial resistance
40
Q

What does virulence factors vary between?

A
  • Different organisms
  • Individual organisms of the same species
41
Q

What is the effect of inoculum size on disease?

A

More likely to get infection if infectious load is large

42
Q

What patient factors determine disease?

A
  • Site of infection
  • Co-morbidities
43
Q

What co-morbidities affect disease outcomes?

A
  • Neonates
  • Recent surgery
  • Diabetes
  • Malignancy
44
Q

What questions must be answered when a patient presents with an infection?

A
  • Is there an infection?
  • Where is the infection?
  • What is the cause of the infection?
  • What is the best treatment?
45
Q

Why may no treatment be given for an infection?

A
  • There may be no treatment available
  • The infection might be self limiting
46
Q

What must be done to determine what infection a patient has?

A
  • History
  • Examination
  • Investigations
47
Q

What should be determined in the history of a patient with an infection?

A
  • Symptoms
  • Potential exposures
48
Q

What information should be gathered about the symptoms of an infection?

A
  • What is the patient complaning of?
  • Are they focal or systemic?
    • Can be both
  • Severity
  • Duration
49
Q

Give 3 examples of systemic symptoms of infection

A
  • Weight loss
  • Fever
  • General malaise
50
Q

What questions must be asked to determine potential exposures to an infection?

A
  • Where have they been?
  • What have they been doing?
  • Who have they been doing it with?
  • Were there any animals involved?
51
Q

What should be looked for on examination of someone with an infection?

A

Organ dysfunctions

52
Q

What are the categories of investigations in a patient with an infection?

A
  • Specific
  • Supportive
53
Q

What are the specific investigations into someone with a infection?

A

Microbiological

54
Q

What is meant by supportive investigations into infection?

A

Investigations which help indicate the possibility of infection, severity, and prognosis, and how the patient is responding to treatment

55
Q

What are the supportive investigations into infection?

A
  • Full blood count
  • C-reactive protein (CRP)
  • Blood chemistry
  • Imaging
  • Histopathology
56
Q

What is being looked for in a FBC when investigating infection?

A
  • Neutrophils
  • Lymphocytes
57
Q

What is CRP indicative of?

A

Infection

58
Q

What is done when conducting a blood chemistry investigation in infection?

A

Liver and kidney function

59
Q

Give an example of where a liver function test can help determine the cause of infection?

A

In viral hepatitis, transaminases normally go up

60
Q

What can kidney function tests give in infection?

A

Dose suggestions for some drugs

61
Q

What imaging is done when investigating infections?

A
  • X-ray
  • Ultrasound
  • MRI
62
Q

How is the precise cause of infection determined?

A

Bacteriology or virology

63
Q

What specimen types are used in bacteriology?

A
  • Swabs
  • Fluids
  • Tissues
64
Q

What can be swabbed to obtain a specimen in bacteriology?

A
  • Throat
  • Rectum
  • Wound
65
Q

What fluids can be used as the specimen in bacteriology?

A
  • Urine
  • Blood
66
Q

What techniques of bacteriology are used?

A
  • M, C, & S
  • Antigen detection
  • Nucleic acid detection
67
Q

What is M, C, & S?

A
  • Microscopy
  • Culture
  • Antibiotic susceptibility
68
Q

What is looked at in the microscopy phase of M, C, & S?

A
  • Bacterial cells
  • Patient cells
69
Q

What can be used to look at bacterial cells?

A

Gram stain

70
Q

What patient cells are looked at in M, C, & S?

A

CSF

71
Q

How is nucleic acid detected in bacteriology?

A

PCR

72
Q

Does the bacteria have to be alive to conduct PCR?

A

No

73
Q

What techiques of virology are used?

A
  • Antigen detection
  • Antibody detection
  • Detecting viral nucleic acid
74
Q

What happens in antigen detection in virology?

A

Use antibody to capture antigen, and then demonstrate presence using flourescent marker

75
Q

What does antigen detection in virology determine?

A

The presence of a virus

76
Q

What happens in antibody detection in virology?

A

Use antigen as capture mechanism

77
Q

What does antibody detection in virology determine?

A

The patient’s response

78
Q

What does the detection of viral nucleic acid determine?

A

DNA or RNA

79
Q

Who is involved in managing infections?

A

All clinicians encounter patients with infections, but specialities whos primary interest in infection are;

  • Infectious diseases
  • Medical microbiology and virology
  • Genitourinary medicine
  • Health protection