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ESA 3 > Infection 1 > Flashcards

Infection 1 Flashcards

This flashcard series incorporates info from lectures, workbook, group work and self study.

1
Q

For my first ever flashcard of ESA 3

What is an infection and how is it caused?

A

Invasion of a host’s tissues by micro-organisms

AND

Subsequent disease caused by:
- Microbial multiplication

  • Toxins
  • Host response
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2
Q

What is meant by ‘commensal’

How are they relevant to humans and infection?

A

Commensalism is a relation between two organism where one derives benifit and the other is unharmed

Microbiota living on the skin and mucosal surfaces engage in a commensal relationship with humans

Normally harmless or even beneficial however transfer to other sites can be harmful (cause infection)

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3
Q

List the ways in which we might get an infection from our environment.

For each give an example of an infection we might acquire via this route.

A

Food

  • Gastroenteritis

Air

  • Influenza

Water

  • Cholera

Animals

  • Malaria

Surfaces

  • Tetanus

Human Contact

  • Syphilis
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4
Q

What is meant by the terms ‘vertical transmission’ and ‘horizontal transmission’?

Give an example of infection that could be transmitted vertically

A

Horizontal Transmission

  • Transmission between organisms

Vertical Transmission

  • Transmission of infection from mother to child at or before birth
  • E.g. HIV
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5
Q

What is an ‘vector’ in regards to infection?

Give an example

A

An organism that can transfer pathogens and parasites from one organism to another, usually remaining uninfected itself

E.g. Mosquitoes are a vector for malaria

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6
Q

What are the modes of horizontal infection?

Hint: 3 basic categories

A

Contact:

  • Direct
  • Indirect
  • Vectors

Inhalation

  • Droplets (small clusters of liquid particles in air)
  • Aerosols (colloid of fine solid/liquid particles in gas/air)

Ingestion

  • E.g. Faecal-oral transmission
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7
Q

What are the 5 stages of an infection?

A

Exposure

Adherence

Invasion

Multiplication

Dissemination

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8
Q

What factors determine the course/severity of an infection?

A

Pathogen

  • Virulence factors
  • Inoculum size
  • Antimicrobial resistance

Patient

  • Site of infection
  • Co-morbidities
  • Immune response
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9
Q

Give some examples of virulence factors

How do they cause disease?

A

Virulence factors

  • Exotoxins (Enzymes, AB toxins, Superantigens, Cytolytic)
  • Endotoxins

These can cause damage either directly, or damage can be consequent to host immune response

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10
Q

What are the 3 basic steps to determining if a patient has an infection?

A

History

Examination

Investigations

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11
Q

You are taking a patient history and suspect infection, what things are particularly important to ask about?

A

Symptoms

  • Focal/systemic
  • Severity
  • Duration

Potential exposures

  • What have you been doing?
  • Who with?
  • Where?
  • Were there animals?
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12
Q

Give some examples of supportive investigations you might carry out with a patient with suspected infection

A

Full blood count

  • Neutrophils + Lymphocytes

C reactive protein

  • Inflammation

Liver and kidney function tests

Imaging

  • Xray
  • Ultrasound
  • MRI

Histopathology

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13
Q

How might you test a patient for bacterial infection and determine the specific species responsible?

A

Take a specimen

  • E.g. Swab, fluid, tissue

M, C&S

  • Microscopy (Bacterial and host cells)
  • Culture bacteria
  • Test antibiotic Susceptibility

Antigen detection

  • ELISA

Nucleic acid detection

  • PCR
  • Sequencing/Hybridisation
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14
Q

What methods are available to test specifically for viral infection?

A

Antigen/antibody Detection

  • ELISA

Viral nucleic acid detection

  • PCR
  • Sequencing/Hybridisation
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15
Q

Who might be involves in treatment of patients with infections?

A

All Clinicians

Specialties with specific interest

  • Infectious disease
  • Medical microbiology and virology
  • Genitourinary
  • Health protection
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16
Q

What is pictured here?

Label the lines

A

A Virus

Top Left Clockwise

  • Envelope
  • Spikes (for attaching to specific cell surfaces)
  • Nucleic acid (DNA or RNA)
  • Protein Coat
17
Q

What are some common symptoms of infection?

What micro-organisms are typically associated with the two major categories of symptom?

A

Systemic (generally viral):

Fever

Fatigue

Weight loss/loss of appetite

Aches, pains, burning, itching (Can be localised)

Localised (generally bacterial):

Redness

Heat

Swelling

Pain

18
Q

How are viruses classified by nucleic acid?

A

Baltimore classification (I to VII)

Classifies virus by nucleic acid type:

I - dsDNA

II - ssDNA

III - dsRNA

IV - (+)ssRNA

V - (-)ssRNA

VI - ssRNA-RT

VII - dsDNA-RT

19
Q

How are class VI and VII of viruses different to classes the other classes of viruses?

A

VI:

Retroviruses (ssRNA-RT) that replicate with reverse transcriptase (creating a DNA intermediate) as opposed to host machinery

VII:

Similar to retroviruses, dsDNA-RT viruses replicate through the use of reverse transcriptase (creating an RNA intermediate) as opposed to host machinery

20
Q

Give examples of Non-enveloped DNA viruses

A

Single stranded:

Parovirus 19

Double stranded:

Adenovirus

BK virus

HPV

JC virus

21
Q

Give examples of Enveloped DNA viruses

A

Double stranded:

Herpes

Hep B

Molluscum

Contagiosum

22
Q

How might we classify viruses by capsid shape?

A

Icosahedral or helical

23
Q

Apart from nucleic acid type and capsid shape, how else might we classify viruses?

A

Enveloped or Non-enveloped

24
Q

Give examples of ss(+), icosahedral, non-enveloped viruses

A

Coxsachievirus

Echovirus

Enterovirus

Hep A, E

Norovirus

25
Q

Give examples of ss(+), Enveloped viruses

A

HIV

Hep C

Rubella

Encephalitis viruses

Yellow fever virus

West nile virus

26
Q

Give examples of ss(-), Helical, Enveloped viruses

A

Ebola, Lassa, Marburg

Measles, Mumps

Influenza, parainfluenza viruses

Respiratory syncytial virus (RSV)

27
Q

Give an example of a ds, Icosahedral, Non-enveloped virus

A

Rotavirus

28
Q

What are bacteriophages?

A

Viruses that infect bacteria and replicate within the bacteria

May be DNA or RNA based

29
Q

What is shown in this diagram?

Label the black boxes

A

Bacteriophage

From top anticlockwise:

Head

Collar

Tail

Long tail fibres

Base plate

30
Q

What are the 3 bacterial shapes?

A

Coccus

Spirillus

Bacillus (plural bacilli)

31
Q

What are the common arrangements of bacterial cocci?

A

Clusters

Chains

(honorable mention to diplococci, which could be both, depending on how you look at things)

32
Q

What is the structural difference between gram negative and gram positive bacteria?

Why do they stain differently and what colours are they?

A

Gram positive:

Plasma membrane is surrounded by thick peptidoglycan cell wall

Stains purple

Thick peptidoglycan cell wall retains crystal violet

Gram negative:

Plasma membrane is surrounded by thin peptidoglycan cell wall and then a lipopolysaccharide outer membrane

Stains red

Thin peptidoglycan cell wall doesn’t retain crystal violet and instad retains red counter stain

33
Q

How does oxygen tolerance of bacteria differ?

A

Aerobes:

Can survive in the presence of oxygen

Obligate anaerobes require oxygen

Anaerobes:

Can survive in absence of oxygen

Obligate anaerobes require an oxygen free environment to survive (unless able to form spores)

34
Q

What are bacterial spores?

What is their relevance to disease?

A

Resistant form of bacteria that can survive extreme conditions (high temperature, dessication, lack of nutrients)

Generally, spores cannot cause disease directly, must first germinate in favourable conditions (however some can secrete toxins)

35
Q

Give examples of gram positive bacteria classified by bacterial shape

A

Cocci:

Staph aureus

Coagulase neg staph

Alpha and beta haemolytic streptococci (strep pyogenes = beta)

Streptococcus pneumoniae

Enterococcus faecalis

Bacilli:

Listeria monocytogenes

Bacillus anthracis

Bacillus cereus

36
Q

Give examples of gram negative bacteria classified by shape

A

Cocci:

Nesseria meningitidis/gonorrhoeae

Moraxella catarrhalis

Acinetobacter baumannii

Bacillus:

E. coli

Klebsiella pneumoniae

Proteus spp

Salmonella typhi

Pseudomonas aeruginosa

Haemophilis influenzae

37
Q

What are the mechanisms of bacterial pathogenesis?

Give an example of a cell feature involved in each mechanism

A

Virulence factors:

Host entry (Polysaccharide capsule)

Adherence (Pili)

Invasiveness (Enzymes such as collagenases)

Iron sequestration (siderophores)

Toxins:

Endotoxins (lipopolysaccharide toxins)

Exotoxins (E.g. Diptheria toxin)

38
Q

What are the broad categories of fungus?

Give examples of each category

A

Yeasts (Single-celled):

Candida albicans

Cryptococcus neoformans

Pneumoystis jiroveci

Molds (multicellular):

Aspergillus spp

Dermatophytes (ringworm, athlete’s foot)

39
Q

What are the broad categories of parasites?

Give examples for each category

A

Protozoa (single celled):

Giaria lamblia

Cryptosporidium parvum

Plasmodium falciparum

Trypsnodoma cruzi

Heminths (Worms, Multicellular)

Roundworms

Tapeworms

Flukes

ESA 3 (54 decks)

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