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Microbiology 1 > INTRODUCTION > Flashcards

INTRODUCTION Flashcards

1
Q

What is a pathogen

A

Is a parasite capable of causing a disease

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2
Q

What is a host

A

An organism that harbors another organism

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3
Q

Define virulence

A

Means Quantitative measure of pathogenicity and is measured by the number of organisms required to cause disease

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4
Q

Define the term infection

A

Means invasion and multiplication of pathogenic microorganism in a bodily part or tissue

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5
Q

What is a normal flora

A

Means microorganisms that are frequently found in various body sites in normal, healthy individuals

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6
Q

Where can normal flora be found in the body?

A

Normal flora can be found in different body sites, including the skin, respiratory tract, gastrointestinal tract, urogenital tract, and oral cavity.

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7
Q

What role does bacteria play in the composition of normal flora?

A

Bacteria are the predominant component of normal flora. They help maintain a balance in the microbial ecosystem, aid in digestion, and prevent colonization by harmful pathogens.

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8
Q

How do microorganisms of the normal flora behave under various conditions?

A

Normal flora organisms can colonize and multiply under specific conditions in particular sites. They coexist with other colonizing organisms and inhibit the growth of competing intruders.

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9
Q

What is the difference between resident and transient flora

A

Resident flora means the microorganism that colonize an area for months or years while transient flora means microorganism that are present at a site temporarily

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10
Q

How are normal flora eliminated

A
  1. By the host inherent immune defence
  2. By competition with the resident flora
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11
Q

What are the advantages of normal flora

A
  1. They produce vitamin B and vitamin K in the intestines
  2. Oral flora contributes to immunity by inducing low levels of circulating and secretory antibodies that may cross react with pathogens
  3. Normal flora may antagonize other bacteria through the production of substances which inhibits or kill nonindigenous species
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12
Q

Disadvantages of normal flora

A
  1. Normal flora may harm their host since some of these bacteria are pathogens
  2. They may cause cause a disease when they change their anatomical location
  3. They can cause disease in immunicompromised individuals
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13
Q
  1. What are the primary physical or mechanical barriers against infection?
A

The skin and mucous membranes (epithelial surface tissues) play crucial roles in preventing infection. Explain how they achieve this.

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14
Q

How does cell adhesion contribute to the barrier function of the skin?

A

Describe how tightly joined cells prevent bacteria from invading deeper tissues.

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15
Q

What is the significance of the sloughing of dead cells in the skin?

A

Renewal and regeneration

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16
Q

What role does keratin play in the outer layers of the epidermis?

A

keratin in maintaining skin integrity.

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17
Q

What are some secretions that contain lysozyme?

A

Tears, perspiration, and saliva contain lysozyme. Lysozyme is an enzyme that can destroy bacterial cell walls.

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18
Q

How does perspiration contribute to creating a hypertonic environment?

A

Perspiration contains high concentrations of salt (sodium chloride). When we sweat, the salt in perspiration makes the external environment around our skin hypertonic. This osmotic imbalance can be unfavorable for many bacteria, preventing their growth.

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19
Q

Which secretion is produced by the liver and disrupts the bacterial cell wall?

A

Bile, produced by the liver and stored in the gallbladder, disrupts bacterial cell walls. It aids in the digestion of fats and also has antimicrobial properties.

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20
Q

Where is hydrochloric acid produced in the body?

A

Hydrochloric acid (HCl) is produced in the stomach by specialized cells called parietal cells. It plays a crucial role in breaking down food and killing ingested pathogens

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21
Q

What makes the skin slightly acidic?

A

Fatty acids contained in the oil secreted from oil glands (sebaceous glands) in the skin contribute to its slight acidity. This acidic pH helps inhibit the growth of certain microbes on the skin.

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22
Q

What is the role of phagocytic cells in nonspecific resistance?

A

Phagocytic cells play a crucial role in nonspecific resistance by ingesting and destroying all microbes that pass into body tissues. They act as the first line of defense against invading pathogens.

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23
Q

How does inflammation contribute to nonspecific resistance?

A

Inflammation is a vital part of the body’s immune response. It contributes to nonspecific resistance by:
~Bringing more white blood cells (such as neutrophils and macrophages) to the site where microbes have invaded.
~Increasing blood flow, which helps deliver immune cells and nutrients to the affected area.
~Activating the immune system to fight off infections and promote tissue repair.

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24
Q

What is the effect of fever on bacterial growth and tissue repair during an infection?

A

Fever serves as a protective mechanism during infections. Its effects include:
1.Inhibiting bacterial growth: Elevated body temperature makes it harder for bacteria to thrive.
2.Increasing the rate of tissue repair: Fever stimulates the body’s repair processes, aiding in healing.

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25
Q

What is the third line of defense in specific resistance?

A

The third line of defense is specific resistance, which relies on antigens found in foreign microbes.

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26
Q

Where does the term “antigen” come from?

A

The term “antigen” comes from ANTI-body GENerating substances.

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27
Q

What happens when an antigen is detected by a macrophage?

A

When an antigen is detected by a macrophage, it causes the T-cells to become activated. This activation by a specific antigen is called cell-mediated immunity. The T-cells secrete interleukin 2, leading to the proliferation of certain cytotoxic T cells and B cells.

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28
Q

What do Cytotoxic T cells secrete, and what is its effect on pathogens?

A

Cytotoxic T cells secrete cytotoxin, which triggers the destruction of the pathogen’s DNA, or perforin, a protein that creates holes in the pathogen’s plasma membrane. These mechanisms help eliminate infected cells.

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29
Q

What do Helper T cells secrete, and what does it stimulate?

A

Helper T cells secrete interleukin 2 (IL-2), which stimulates cell division of both T cells and B cells. This activation enhances the immune response.

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30
Q

When do Memory T cells become active?

A

Memory T cells remain dormant after the initial exposure to an antigen. They become active when there is another exposure to the same antigen, allowing for a faster and more efficient immune response.

31
Q

How do cytotoxic T cells recognize infected body cells?

A

Cytotoxic T cells are capable of recognizing antigens on the surface of infected body cells. When they bind to these infected cells, they secrete cytokines that induce apoptosis (cell suicide) in the infected cell. Additionally, they release perforins that cause lysis of the infected cell.

32
Q

How can T-cells destroy microbes?

A

T-cells can either directly destroy the microbes or use chemical secretions to destroy them. For example, they can secrete cytotoxin, which triggers the destruction of the pathogen’s DNA, or perforin, a protein that creates holes in the pathogen’s plasma membrane. These mechanisms help eliminate infected cells.

33
Q

What happens when T cells stimulate B cells?

A

When T cells stimulate B cells, it leads to B cell division. This results in the formation of plasma cells that are capable of producing antibodies and memory B cells. The memory B cells play a crucial role in protecting against future attacks by the same antigen.

34
Q

What is the role of memory B cells when the same antigen enters the body later?

A

Memory B cells remain dormant until there is another exposure to the same antigen. When the same antigen enters the body later, memory B cells divide to make more plasma cells and memory cells. This enhanced response helps protect against future attacks by the same antigen.

35
Q

What is called antibody-mediated immunity?

A

Antibody-mediated immunity occurs when T cells activate (stimulate) B cells to divide into plasma cells. These plasma cells then produce antibodies, which play a crucial role in specific immune responses.

36
Q

What are antibodies also called?

A

Antibodies are also known as immunoglobulins or Ig’s.

37
Q

How are antibodies shaped?

A

Antibodies have a Y-shaped structure.

38
Q

How do antibodies function in the body?

A

Antibodies circulate through the bloodstream and bind to specific antigens, thereby attacking microbes.

39
Q

How many classes of antibodies are there?

A

There are five classes of antibodies: IgG, IgM, IgA, IgE, and IgD.

40
Q

Name 4 way that antibodies function.

A
  1. is by neutralizing an antigen.
  2. Activating compliment
  3. Precipitating antigens
  4. Facilitating phagocytosis
41
Q

What is the host-microbe relationship?

A
  1. Symbiosis: An association of two organisms living together.
  2. Commensalism: One organism benefits, while there is no beneficial or harmful effect to the host.
  3. Parasitism: One species benefits at the expense of the other.
42
Q

What is pathogenesis

A

Pathogenesis refers to the process by which bacteria cause disease.

43
Q

What does an organism’s pathogenicity depend on?

A

An organism’s pathogenicity depends on its ability to:
1.Invade a host.
2.Multiply within the host.
3.Avoid being damaged by the host’s defenses.

44
Q

How does toxicity relate to pathogenicity?

A

Pathogenicity also depends on the organism’s toxicity.

45
Q

How are organisms that can establish infection with a relatively low infective dose described?

A

Such organisms are considered more virulent than those requiring a high number for infection to occur.

46
Q

What are the most common portals of entry for disease-causing microbes?

A

The most common portals are external and internal body surfaces

47
Q
  1. What is the initial step in the process of pathogenesis
A

The initial step is the transmission of the infectious agent (bacterial) to the host.

48
Q

What happens after bacteria colonize the host

A

After colonization, bacteria remain adherent at the site and then invade the host system.

49
Q

When is a disease caused according to this information?

A

The disease is caused after surviving the host immune system

50
Q

How can potential pathogens enter the body?

A

Potential pathogens can enter the body through various routes, including respiratory, gastrointestinal, urinary or genital tracts, or directly into tissues through insect bites or accidental or surgical trauma to the skin.

51
Q

What is colonization in the context of disease occurrence?

A

Colonization refers to the establishment of a stable population of bacteria on the host’s skin or mucous membranes. It is an essential step for many pathogenic bacteria to initiate infection.

52
Q

What role does adhesion play in infection?

A

Adhesion is crucial for bacteria as it allows them to attach to host tissues, facilitating colonization and penetration through tissues. Successful adhesion is necessary for the establishment of a focus of infection.

53
Q

How is invasion described in this context?

A

Invasion involves the penetration of host cells and tissues beyond the skin and mucous surfaces. It is mediated by a complex array of molecules, often referred to as ‘invasins.’

54
Q

How do pathogens survive in host cells?

A

Pathogens can circumvent phagocytosis by extracellular mechanisms, allowing them to survive

55
Q

Mention the steps of disease occurrence

A
  1. Transmission
  2. Colonization
  3. Adhesion
  4. Invasion
  5. Survivor of the host
    6.tissue injury
56
Q

How can potential pathogens enter the body?

A

Potential pathogens can enter the body through various routes, including respiratory, gastrointestinal, urinary or genital tracts, or directly into tissues through insect bites or accidental or surgical trauma to the skin.

57
Q

What is colonization in the context of disease occurrence?

A

Colonization refers to the establishment of a stable population of bacteria on the host’s skin or mucous membranes. It is an essential step for many pathogenic bacteria to initiate infection.

58
Q

What role does adhesion play in infection?

A

Adhesion is crucial for bacteria as it allows them to attach to host tissues, facilitating colonization and penetration through tissues. Successful adhesion is necessary for the establishment of a focus of infection.

59
Q

How is invasion described in this context?

A

Invasion involves the penetration of host cells and tissues beyond the skin and mucous surfaces. It is mediated by a complex array of molecules, often referred to as ‘invasins.’

60
Q

How do pathogens survive in host cells?

A

Pathogens can circumvent phagocytosis by extracellular mechanisms, allowing them to survive within host cells.

61
Q

What is an acute disease?

A

An acute disease develops rapidly and runs its course quickly.

62
Q

How does a chronic disease progress?

A

A chronic disease develops more slowly, is usually less severe, and persists for a long period.

63
Q

What characterizes a latent disease?

A

A latent disease is characterized by a period of inactivity (for example, Herpes).

64
Q

What is a local infection?

A

A local infection remains confined to a specific area of the body.

65
Q

How does a systemic infection manifest?

A

A systemic infection is a generalized infection that affects most parts of the body.

66
Q

Explain 5 types of infectious diseases

A
  1. Acute disease- develops rapidly and runs its course quickly
  2. Chronic disease- develops more slowly, is usually less severe and persist for a long period
  3. Latent disease- Characterized by period of inactivity
  4. Local infection- Confined to a specific area
  5. Systemic infection- generalized infection, affects most of the body
67
Q

What strategies are involved in preventing disease related to infections?

A

Strategies involve interrupting or minimizing the risk of infection when exposures occur.

68
Q

How do medical procedures contribute to controlling or clearing an infection?

A

The severity of the infection, which is determined by host and microbial interactions.
Accuracy in diagnosing the pathogen or pathogens causing the infection.
Whether the patient receives appropriate treatment for the infection.

69
Q

Mention some of the prevention practices to prevent transmission of diseases

A
  1. Practice good hygiene
  2. Avoid contact with people who are sick with contagious infection
  3. Block the spread of airborne microorganism by wearing masks or isolating persons with infections
  4. Use sterile medical techniques
70
Q

How can we control microbial reservoirs

A
  1. Sanitation and disinfection
  2. Sewage treatment
  3. Food preservation
  4. Water treatment
  5. Control of pests and insect vector populations
71
Q

How to minimize risk before or shortly after exposure

A
  1. Immunizations or vaccination
  2. Cleansing and use of antiseptics
  3. Prophylactic use of anti microbial agents
72
Q

Differentiate antiseptic and disinfectant

A

Disinfectants:
Function: Disinfectants are chemical agents used to kill or inhibit the growth of microorganisms on inanimate surfaces (such as countertops, floors, medical equipment, etc.).

Antiseptics:
Function: Antiseptics are chemical agents used to kill or inhibit the growth of microorganisms on living tissues (such as skin, mucous membranes, wounds, etc.).

73
Q

What are the General modes of antimicrobial action. (Understanding these mechanisms helps clinicians choose appropriate antibiotics for different infections)

A

Antimicrobial agents, including antibiotics, exhibit various modes of action to combat infections. Here are some of the key mechanisms by which antimicrobials exert their effects:
Interference with Cell Wall Synthesis: Some antibiotics disrupt the formation of bacterial cell walls. For instance, β-lactam antibiotics (such as penicillin) inhibit enzymes involved in cell wall synthesis, leading to cell lysis and death1.
Inhibition of Protein Synthesis: Certain antibiotics target bacterial ribosomes, preventing protein synthesis. Examples include aminoglycosides (like gentamicin) and macrolides (such as erythromycin)2.
Interference with Nucleic Acid Synthesis: Antimicrobials like fluoroquinolones (e.g., ciprofloxacin) inhibit DNA gyrase and topoisomerase, essential enzymes for DNA replication and repair3.
Inhibition of Metabolic Pathways: Some antibiotics interfere with specific metabolic pathways unique to bacteria. For instance, sulfonamides block folic acid synthesis, disrupting nucleotide production4.
Inhibition of Membrane Function: Antimicrobials may disrupt bacterial cell membranes, affecting their integrity and function. Polymyxins are an example of such agents.
Inhibition of ATP Synthase: ATP synthase inhibitors, like daptomycin, disrupt energy production in bacterial cells, leading to their demise2.

Microbiology 1 (27 decks)

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