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Module 1 - CVS > Module 6 - Microbiology > Flashcards

Module 6 - Microbiology Flashcards

1
Q

Microbe

A

Microbes are tiny living organisms that are found all around us and are too small to be seen by the naked eye (microscopic). They include bacteria, archaea, single-cell eukaryotes, and viruses

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2
Q

Commensalism

A

one benefits one not harmed

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3
Q

Mutualism

A

both benefit and depend on each other

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4
Q

Parasitism

A

one benefits, one adversely affected

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5
Q

Opportunism

A

a change in living relationship resulting in parasitism

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6
Q

Outbreak

A

relatively high number of infections are observed where no cases or only sporadic cases occurred in the past

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7
Q

epidemic

A

sudden rapid rise in the incidence of a disease in a particular population

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8
Q

Pandemic

A

global epidemic

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9
Q

endemic

A

disease that is always present in a given population. there is a permanent reservoir (human or other animals).

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10
Q

Identify Koch’s 4 postulates

A
  1. suspected pathogen must be present in all cases of disease and absent from health animals
  2. suspected pathogen must be grown in pure culture
  3. cells from pure culture of suspected pathogen must cause disease in health animal
  4. suspected pathogen must be reisolated and shown to be the same as the original
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11
Q

Infection

A

when microorganisms invade host tissue and multiply

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12
Q

subclinical infection

A

no symptoms apparent but immune response is induced

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13
Q

localised infection

A

confined to one area of the body

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14
Q

systemic infection

A

infection spreads to other organ systems

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15
Q

disease

A

harmful alteration to the host

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16
Q

pathogen

A

microorganism capable of causing disease

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17
Q

pathogenesis

A

process of disease arising

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18
Q

pathogenicity

A

measure of ability of a pathogen to cause disease

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19
Q

pathogenic determinant/virulence factor

A

feature of a pathogen that influences how well it can cause disease

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20
Q

Gram positive bacteria

A

thick peptidoglycan layer and has a plasma membrane
purple colour

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21
Q

Gram negative bacteria

A

thin peptidoglycan layer
has outer membrane and inner membrane
red in colour

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22
Q

why it is important to know about the bacterial characteristics particularly in the health care setting

A
  • Accurate ID of bacteria needed for choosing treatment
  • In general, the Gram status, morphology and functional characteristics would be sufficient information for the appropriate treatment
    More information to narrow down to species level
  • Ultimate knowledge: DNA sequencing; expensive; slow (but improving)
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23
Q

Macroscopy

A
  • Colony morphology & phenotype (seen with the naked eye)
  • Bacterial colony morphology: size, shape, pigmentation, elevation, margin, opacity, surface texture
  • Requires culture on solid media & isolating single colonies (16 streak technique)
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24
Q

Microscopy

A

Examination of bacterial cells by their morphology (cell shape)
Problem: bacteria (often) colourless

Only visible in phase-contrast microscope

Staining of the bacteria may help

25
Q

Why do bacteria like living together

A

Bacteria rarely live as single cells

They form colonies with other individuals (often from the same species)

They can also form biofilms (single or mixed species)

Significant for infection control & treatment

26
Q

The steps of infection

A
  1. attachement and entry into body
  2. local or general spread in body
  3. multiplication
  4. evasion of host defenses
  5. shedding
  6. cause damage in host
27
Q

Bacterial Reproduction

A

Bacterial cells undergo Binary Fission to reproduce a cell into two parts which involves:
* DNA replication to get two copies
* Moving of the DNA strands to opposite ends of the cell
* Splitting of the cell in the middle into two separate bacteria that has the same genetic material

28
Q

Generation Time

A

is time taken for one cell to reproduce itself

29
Q

Bacterial Reproduction: Growth Phases

A

Replication results in an exponential increase in cell number

  1. Lag Phase
    Initial adaptation to conditions
  2. Logarithmic Phase
    Exponential increase in cells
  3. Stationary Phase
    Rate of cell division equals cell death
  4. Death Phase
    Decrease in cell numbers
30
Q

How do we measure bacterial growth

A

Turbidity which can be measured using a spectrophotometer

  • Increased turbidity is directly related to the number of cells * Can be seen by the eye
  • Can be measured using optical density (OD)
  • More cells = more scatter = higher OD
31
Q

Viruses

A

Are not living organisms because they:
* Consist only of DNA or RNA and protein
* Are incapable of independent reproduction * Are smaller than any cell (~0.1 𝜇m)
* Have no cell membrane
* Do not have ribosomes
* Have few enzymes for metabolism

32
Q

Properties of Viruses

A
  • Infect bacterial, plant and animal cells
  • Are large, inert systems consisting of nucleic acid (DNA or RNA) and protein
  • No cell wall, ribosomes, mitochondria or nucleus
    Ÿ Thus, cannot produce energy or synthesize proteins
  • Incapable of independent replication and require living host— they are “obligate intracellular parasites”
33
Q

Classification of Viruses

A
  • Type of nucleic acid
    DNAorRNA
  • Arrangement of nucleic acid
    *Double-stranded or single-stranded
    Linear or circular
  • Structure of the virus particle Enveloped/“naked”
  • Symmetry of capsid Icosahedral
    Helical
    complex
34
Q

The viral lifecycle

A
  1. Attachment to host cell surface
  2. Penetration into host cell cytoplasm
  3. Uncoating to release viral genome
  4. Replication of viral genomes, mRNA and proteins
  5. Assembly of viral components
  6. Maturation and release of progeny viruses through host membranes
35
Q

Key process: Attachment

A

Interaction between viral surface protein:
* Capsid component
* Viral attachment protein
And host cell surface protein (receptor)

Tropism
Viruses target specific cells
* Cellular tropism
* Tissue tropism
* Host tropism

36
Q

Events in virus replication

A
  1. early viral protein synthesis
  2. late viral protein synthesis
37
Q

General patterns of viral infections

A
  1. Acute infection
  2. non-productive latent infection
  3. productive chronic infection
  4. transformation
38
Q

Immunopathology

A

antibodies and immune cells destroy
infected cells → tissue damage

39
Q

Fever

A
  • Stimulates the immune response
  • Inhibits virus replication–most viruses very temperature
    sensitive
40
Q

*Inflammation

A
  • Redness
  • Localized heat
  • Swelling
  • Pain
  • Loss of function (e.g., eye infection)
41
Q

Human papillomavirus (HPV)

A

DNA virus
common cold of sexual activity

42
Q

SARS-CoV-2

A

RNA virus
Transmission: droplet spread, airborne, faecal-oral

43
Q

Fungi

A

Fungi are eukaryotic multicellular (in many cases
multinucleate) organisms with thick carbohydrate cell walls

Three major groups:
1. Macroscopic filamentous fungi with large fruiting body (Eg. Mushrooms)
2.Multicellular filamentous moulds
3.Single-celled yeasts

44
Q

Basic fungal structure

A
  • Thick carbohydrate cell wall serves a few functions: 1. Protection from the environment
    2. Acquisition of nutrients
    3. Cell recognition & Mating
  • Similar to the plasma membrane to other eukaryotes
  • Therefore, finding a drug target is difficult as it would target
    human cells as well
45
Q

List 3 types of fungal innfections (aka mycoses)

A
  1. Superficial mycoses (most common)
    * Fungus grows on body surfaces e.g., Skin, hair, nails, mouth
    * Example: Athlete’s foot, thrush, ringworm
  2. Subcutaneous mycoses
    * Fungus grows in the deeper layers of the skin * Example: Madura foot
  3. Systemic mycoses
    * Fungus grows/spreads into internal organs
    * Example: histoplasmosis, systemic candidiasis
46
Q

List the three types of parasites

A
  1. Helminths (worms)
  2. Protozoa
  3. Arothropods
47
Q

Helminths (worms)

A
  • Enterobius vermicularis (AKA pinworm)
  • The most common type of human worm infection
  • Faecal-oral transmission (ingestion of eggs)
  • Symptoms include: pruritus (itchy skin), irritability, insomnia
  • Reinfection is very common
48
Q

Medically Relevant Protozoa: Plasmodium spp.

A
  • 5 different species of Plasmodium are of medical
    importance and causes malaria
  • P. falciparum causes the most deaths
  • Malaria is a severe global problem (> 1.5 million deaths/year)
  • Transmitted via the Anopheles mosquito
  • In humans, it results in infection of blood and liver
49
Q

Arthropod

A
  • Ectoparasites (eg. Lives outsides the host but feeds on host tissue/blood)
  • Two main groups:
  • Arachnids (2 segments, 8 legs) – ticks, mites * Insects (3 segments, 6 legs) – fleas, lice
  • They also serve as vectors and transmit pathogens
50
Q

Describe how the healthcare environment contributes to the incidence of infectious disease

A

Of particular concern:
* Concentration of vulnerable and/or infective persons
* Repeated contact with equipment, carers/therapists/other staff * Reservoir of non-typical pathogens/highly resistant organisms

Can lead to:
* Nosocomial ( = hospital) acquired infections
* More recently — HCAI ( = health care associated infections)

51
Q

Describe what is meant by MRSA, its key virulence factors and pathophysiology

A

MRSA is a type of bacteria that is resistant to many antibiotics, making it difficult to treat.
Produces a number of virulence factors;
- PVL
- alpha-toxin
- exotoxins.
- MRSA strains are capable of forming biofilms, which are communities of bacteria that are embedded in a self-produced extracellular matrix.
- Can occur in both community and healthcare settings
- Can be transmitted through direct contact with an infected person or contaminated surfaces.
- MRSA infections can cause a range of symptoms, from mild skin infections to life-threatening infections such as sepsis.

52
Q

Describe other significant bacterial HCAIs

A

healthcare-associated infections (HCAIs) are infections that patients acquire while receiving medical treatment in healthcare settings. Some significant bacterial HCAIs;
- Enterococcus species
- E. coli
- C. difficile
- CRE
- Acinetobacter baumannii
- Klebsiella pneumoniae
- Pseudomonas aeruginosa.
These bacteria can cause a range of infections, from mild to severe, and can be difficult to treat due to antibiotic resistance.

52
Q

Understand basic antibiotic modes of action

A

antibiotics are drugs that are used to treat bacterial infections by targeting specific bacterial structures or processes
Modes of action of antibiotics;
- inhibition of cell wall synthesis
- inhibition of protein synthesis
- interference with nucleic acid synthesis
- inhibition of a metabolic pathway
- inhibition of membrane function
- inhibition of ATP synthase

Different classes of antibiotics target different bacterial structures or processes, and the choice of antibiotic depends on the type of infection and the susceptibility of the bacteria causing the infection.

53
Q

Describe bacterial antibiotic resistance mechanisms

A
  1. Production of enzymes
  2. Alteration in the bacterial cell binding sites
  3. Change in membrane permeability
  4. Producing alternate metabolic pathways/drug efflux pump
  5. Biofilm formation
54
Q

Describe what human practices can lead to antibiotic resistance and what can be done to prevent it

A

human practices that can lead to antibiotic resistance:
- overuse and misuse of antibiotics
- failure to complete a full course of antibiotics
- use of antibiotics in animal feed
- poor infection prevention and control

To prevent antibiotic resistance;
- only use when necessary
- the full course of antibiotics should be completed
- good hygiene practices
- vaccination should be practiced
- the use of antibiotics in animal feed should be reduced
- prevention and control practices should be implemented in healthcare facilities

55
Q

Infection control measures

A

Standard precautions
*Hand hygiene
* Use of PPE where appropriate
* Includes environmental controls—waste management; routine cleaning; spill management

Additional precautions
* Contact precautions
PPE, avoid patient contact, single use equipment
* Droplet precautions
Contact precautions,+surgical mask for carer and patient
* Airborne precautions
Contact precautions,+single occupancy room (neg pressure),patient respirator during transfer

56
Q

Sterilisation vs. Disinfection

A

Sterilisation—the killing or removal of all viable organisms,
including spores
* Heat (wet/dry autoclave)
* Irradiation (Gamma vs UV irradiation)

Disinfection—the killing of many but not all microorganisms
* Pasteurisation (Heat & rapid cooling)
* Filtration (0.22 uM filter)
* Chemical disinfectant (chlorohexidine, ethanol)

57
Q

Describe how antimicrobial resistance can be transferred (gene transfer)

A
  • Transformation
  • Transduction
  • via bacteriophage *
  • Conjugation
  • Bacterial “mating”
  • Transposition
  • Through transposons

Module 1 - CVS (7 decks)

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