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MEDyear1 > WEEK9 > Flashcards

WEEK9 Flashcards

(61 cards)

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1
Q

Write out the Chain of Infection?

A

Infectious agent → Reservoir → Portal of exit → Means of transmission → Portal of entry → Susceptible host → Infectious agent.

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2
Q

What are common reservoirs for microbial growth?

A

Humans (symptomatic or carriers), animals, inanimate objects.

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3
Q

What are common modes of transmission for microbes?

A

Contact, Inoculation, Droplet, Airborne, Vehicles, Transplacental/in-utero.

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4
Q

What are common portals of entry and exit for infectious agents?

A

Respiratory, Conjunctiva, Urogenital, Gastrointestinal, Skin, Placenta.

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5
Q

What factors make a host more susceptible to infection?

A

Underlying disease, extreme ages, malnutrition, invasive devices, surgery, antibiotics, immunocompromised state, steroids/immunosuppressives.

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6
Q

What are the primary ways to control microbial growth?

A

Prevent access, kill microbes, reduce their numbers, inhibit growth.

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7
Q

What environmental factors influence microbial growth?

A

Temperature, moisture, osmotic pressure, pH, oxygen, and nutrient availability.

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8
Q

Why must cleaning occur before sterilization or disinfection?

A

To remove dirt, organic matter, grease, or blood that may interfere with microbial killing.

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9
Q

What is sterilization?

A

Removal/killing of all viable organisms, typically used for equipment that penetrates sterile tissue.

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10
Q

What is disinfection?

A

Removal/killing of most viable organisms, used for surfaces or human skin.

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11
Q

What is antisepsis?

A

Removal of microbes from the skin.

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12
Q

What methods can be used for sterilization and disinfection?

A

Heat (moist/dry), radiation, filtration, chemical treatments.

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13
Q

What are the classifications of medical devices based on microbial control?

A

Critical items (enter sterile tissue or vascular system, must be free of spores); Semi-critical items (contact mucous membranes, can have low spores); Non-critical items (contact intact skin, e.g. crutches, BP cuff, bedpan).

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14
Q

What are common chemical disinfectants?

A

Phenolics, Iodine (iodophors), Chlorine, Chlorhexidine, Alcohol, Quaternary ammonium compounds.

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15
Q

What are nosocomial infections?

A

Hospital-acquired infections due to procedural breakdown.

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16
Q

What are common types of nosocomial infections?

A

Urinary tract infections, surgical wound infections, blood infections, pneumonia.

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17
Q

What are the primary modes of nosocomial infection transmission?

A

Self-infection, cross-infection, environmental infection.

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18
Q

How can a host’s ability to resist infection be enhanced?

A

Active/passive immunization, prophylactic antibiotics, care of invasive devices, postoperative precautions, isolation.

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19
Q

What is a fungus?

A

Eukaryotic cell, exists as Yeast, Moulds, or Dimorphic (both forms).

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20
Q

What features differentiate fungal cells from human cells?

A

Fungal cell walls contain β-glucans, chitin, and ergosterol instead of cholesterol.

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21
Q

What are the basic morphological structures of fungi?

A

Hyphae (septate or non-septate); Mycelium (thick mat of hyphae); Yeast form (budding); Pseudomycelium (single yeast cells in chains).

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22
Q

Why are fungal cells good targets for antifungals?

A

Cell membrane (Sterols, whereas bacteria have none); Cell wall (Glucans, mannans, chitin, chitosan, unlike bacteria).

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23
Q

How do fungi grow?

A

Yeasts → Budding daughter cells; Moulds → Hyphae extension; Dimorphic fungi → Mould at 25°C, Yeast at 37°C (Candida is the exception).

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24
Q

What are major diseases caused by fungal infections?

A

Allergy: Asthma, allergic rhinitis, Hypersensitivity Pneumonitis, Allergic Aspergillus Sinusitis, ABPA.; Toxins: Aflatoxin (from Aspergillus, linked to liver cancer).

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25
What types of fungal infections exist?
Cutaneous → Dermatophytes infect skin, hair, nails.; Subcutaneous → Follows puncture wounds (e.g. rose thorn).; Invasive fungi → Acquired via inhalation.
26
How are cutaneous fungal infections diagnosed?
Skin scrapings, nail clippings, treated with KOH breakdown & fungal culture, sometimes fluorescence staining.
27
What are the four major invasive fungal pathogens?
Candida, Cryptococcus, Pneumocystis jiroveci, Aspergillus.
28
What is Candida, and where does it commonly appear?
Yeast, appears after antibiotics. Causes oral thrush, Candida esophagitis (HIV/AIDS). Can form biofilms.
29
What are the two major species of Cryptococcus?
C. neoformans → Found in pigeon faeces, causes meningitis in immunosuppressed.; C. gattii → Found in river red gums, infects healthy people.
30
What is Aspergillus, and why is it dangerous?
Airborne spores, worsens lung infections, can cause invasive aspergillosis in immunocompromised individuals, mortality 40-90%.
31
What must most pathogens do to cause disease?
Enter the body, Colonise the host, Evade host defenses, Multiply and disseminate, Cause damage to host
32
What happens if a cell cannot adapt to stress or an injurious stimulus?
It undergoes cell injury, which can be reversible or irreversible. Severe/progressive injury leads to necrosis or apoptosis.
33
Define hypertrophy, hyperplasia, atrophy, and metaplasia.
Hypertrophy = Increased cell & organ size; Hyperplasia = Increased cell numbers; Atrophy = Decreased cell numbers & organ size; Metaplasia = Change in cell morphology.
34
What are common causes of cell injury?
Infectious agents, chemical agents, O₂ deprivation, immunological reactions, genetic factors, nutritional imbalances, physical agents, ageing.
35
What are the 5 cardinal signs of inflammation?
Rubor (redness), Tumor (swelling), Calor (heat), Dolor (pain), Functio laesa (loss of function).
36
What factors influence tissue response to injury?
Size/volume of injured tissue, type of tissue, duration of injury.
37
What are the three categories of tissue regeneration ability?
Labile (continuous proliferation), Stable (rarely replicates but can upon injury), Permanent (no regeneration capacity).
38
What factors influence whether a tissue regenerates or repairs?
Size of injury (small vs large), Type of tissue (labile/stable vs permanent), Duration of injury (acute vs chronic).
39
How does healing occur by first intention?
Cutaneous wound healing via epithelial regeneration & connective tissue scar formation.
40
How does healing occur by second intention?
Occurs in large wounds (burns, ulceration, ischemic necrosis). Combination of regeneration & scarring. Granulation tissue forms, wound contracts, fibrosis completes healing.
41
What is reperfusion injury?
Effects of ischaemic injury appear after blood flow is restored due to ROS production leading to lipid peroxidation, protein misfolding, and DNA mutations.
42
What types of tissue necrosis exist?
Coagulative, liquefactive, caseous, fat, fibrinoid, gangrenous.
43
What are the major mechanisms of cell injury?
Energy failure, blockage of metabolic pathways, mechanical disruption, failure of membrane integrity, membrane damage, DNA damage or loss.
44
What is the difference between labile, stable, and permanent tissues?
Labile continuously proliferate, stable replicate infrequently but can respond, and permanent cells do not regenerate.
45
What are examples of labile, stable, and permanent tissues?
Labile: Skin epithelium; Stable: Pancreas; Permanent: Heart.
46
What are the primary stages of normal wound healing?
Haemostasis, inflammation, proliferation, maturation.
47
What are common problems with fracture healing?
Movement, gross misalignment, interposed soft tissue, infection, pre-existing bone disease.
48
What factors influence tissue repair?
Infection, nutrition, glucocorticoids, mechanical variables, poor perfusion, foreign bodies, location of injury, aberrations of cell growth.
49
What defines a microorganism?
Too small to be seen without magnification. Includes prokaryotes, single-celled eukaryotes, fungi, protozoa, viruses.
50
What are medically important eukaryotic microbes?
Protists: Plasmodium spp (Malaria), Trypanosoma spp (Sleeping sickness), Entamoeba spp (Amoebic dysentery); Fungi: Candida albicans (Oral & genital infections), Dermatophytes (Ringworm/Tinea), Aspergillus (Aspergillosis).
51
What are the structural differences between Gram-positive and Gram-negative bacteria?
Gram-positive = thick peptidoglycan layer; Gram-negative = lipopolysaccharide.
52
How does Gram staining differentiate bacterial types?
Thick peptidoglycan stains purple, thin peptidoglycan stains pink. Some bacteria require acid-fast staining due to waxy lipids (e.g. Mycolic acid).
53
What are common bacterial shapes?
Rod-shaped = Bacilli, Dots = Cocci.
54
What are medically important Gram-positive bacteria?
Staphylococcus aureus (skin infections), Streptococcus pyogenes (pharyngitis), Streptococcus pneumoniae (pneumonia), Clostridium perfringens (gas gangrene).
55
What are medically important Gram-negative bacteria?
Escherichia coli (UTI, diarrhea), Salmonella (gastroenteritis), Neisseria meningitis (meningitis/septicemia), Haemophilus influenzae (meningitis, pneumonia).
56
What are key bacterial structures and their functions?
Flagella (motility), Capsule (immune evasion), Pili (adherence), Spores (environmental survival).
57
What defines viruses?
Obligate intracellular parasites with a protein coat (capsid) surrounding genetic material (DNA or RNA). Some have envelopes acquired from host cells.
58
What is the general virus replication cycle?
Attachment → Entry → Replication → Assembly → Release (via cell lysis or budding).
59
What are examples of medically important DNA viruses?
Hepatitis B virus (Hepatitis), Herpesvirus (Chicken pox, shingles, genital herpes), Papillomavirus (Skin warts, cervical cancer).
60
What are examples of medically important RNA viruses?
Influenza virus (Influenza), Measles virus (Measles), Rotavirus (Gastroenteritis), SARS-CoV-2 (COVID-19).
61
What are the two major subdivisions of immunity?
Innate & Adaptive immunity.

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