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Questions and Answers
Which transmission mode occurs when a mother passes an infection to her child during pregnancy?
Which transmission mode occurs when a mother passes an infection to her child during pregnancy?
- Blood-borne transmission
- Inhalation
- Vertical transmission (correct)
- Vector borne transmission
What is the primary characteristic of innate antigen-nonspecific immune defenses?
What is the primary characteristic of innate antigen-nonspecific immune defenses?
- They are only effective through vaccination.
- They rely exclusively on antibodies.
- They are specific to particular antigens.
- They provide immediate response to pathogens. (correct)
Which of the following is NOT considered a first line of defense against infection?
Which of the following is NOT considered a first line of defense against infection?
- Sneezing
- Vomiting
- Natural killer cells (correct)
- Coughing
What is the role of lactoferrin in the body?
What is the role of lactoferrin in the body?
What kind of infection transmission occurs during delivery?
What kind of infection transmission occurs during delivery?
What is the primary goal of the complement system in the immune response?
What is the primary goal of the complement system in the immune response?
Which cells are responsible for engulfing pathogens during innate immunity?
Which cells are responsible for engulfing pathogens during innate immunity?
What is a characteristic of inflammation?
What is a characteristic of inflammation?
What role do microbial toxins play in pathogenic infections?
What role do microbial toxins play in pathogenic infections?
What type of toxin is secreted by bacteria and possesses enzymatic activity?
What type of toxin is secreted by bacteria and possesses enzymatic activity?
How do leukocytes contribute to the immune response during inflammation?
How do leukocytes contribute to the immune response during inflammation?
Which component is not involved in the innate immune response?
Which component is not involved in the innate immune response?
What triggers the inflammatory response in the body?
What triggers the inflammatory response in the body?
What is the primary difference between infection and infectious disease?
What is the primary difference between infection and infectious disease?
Which type of bacteria are known to cause disease only in individuals with preexisting conditions?
Which type of bacteria are known to cause disease only in individuals with preexisting conditions?
How do strict primary pathogens differ from opportunistic pathogens?
How do strict primary pathogens differ from opportunistic pathogens?
What do commensal bacteria do in relation to the host?
What do commensal bacteria do in relation to the host?
What factor does NOT contribute to infectious disease caused by pathogens?
What factor does NOT contribute to infectious disease caused by pathogens?
What describes carriers in the context of bacterial infections?
What describes carriers in the context of bacterial infections?
Which of the following is NOT a source of exogenous infections?
Which of the following is NOT a source of exogenous infections?
What does immunopathogenesis refer to?
What does immunopathogenesis refer to?
Which statement about infection is correct?
Which statement about infection is correct?
What defines saprophytes in the context of microbial life?
What defines saprophytes in the context of microbial life?
What is a characteristic feature of exotoxins?
What is a characteristic feature of exotoxins?
Which class of exotoxins is characterized by membrane disruption and pore formation?
Which class of exotoxins is characterized by membrane disruption and pore formation?
How are A-B toxins structured?
How are A-B toxins structured?
What effect do superantigens have on the immune system?
What effect do superantigens have on the immune system?
Which statement about endotoxins is true?
Which statement about endotoxins is true?
What is the main function of pore-forming toxins (PFTs)?
What is the main function of pore-forming toxins (PFTs)?
Which type of toxins are primarily associated with the symptoms of diseases like diphtheria and tetanus?
Which type of toxins are primarily associated with the symptoms of diseases like diphtheria and tetanus?
What is a significant characteristic of thermolabile proteins?
What is a significant characteristic of thermolabile proteins?
Flashcards
Asymptomatic infection
Asymptomatic infection
A relationship between a microbe and a host where the microbe is present but does not cause disease.
Saprophytes
Saprophytes
Microbes that live on dead organic matter, like soil or decaying plants.
Commensal bacteria
Commensal bacteria
Bacteria that normally live on the host without causing harm.
Pathogenic bacteria
Pathogenic bacteria
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Strict/Primary pathogens
Strict/Primary pathogens
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Opportunistic pathogens
Opportunistic pathogens
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Infection
Infection
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Disease
Disease
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Transmission
Transmission
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Carriers
Carriers
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Vertical transmission
Vertical transmission
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Prenatal/congenital infection
Prenatal/congenital infection
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Perinatal infection
Perinatal infection
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Postnatal infection
Postnatal infection
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Lactoferrin
Lactoferrin
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Innate Immunity
Innate Immunity
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Adaptive Immunity
Adaptive Immunity
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Complement System
Complement System
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Phagocytes
Phagocytes
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Inflammation
Inflammation
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Microbial Toxins
Microbial Toxins
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Exotoxins
Exotoxins
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Endotoxins
Endotoxins
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Pore-forming toxins (PFTs)
Pore-forming toxins (PFTs)
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Membrane-disrupting enzymes
Membrane-disrupting enzymes
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A-B toxins
A-B toxins
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Superantigens
Superantigens
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LPS
LPS
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Antigenicity
Antigenicity
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Study Notes
Bacterial Pathogenesis Mechanisms
- Bacteria cause disease through infection, which involves the growth and multiplication of bacteria within or on the body, potentially leading to disease development.
- Infection does not always result in disease.
- The host's defense mechanisms play a crucial role; infectious disease occurs when the damage caused by pathogens exceeds the host's immune system's response.
- Bacteria can be classified into different categories based on their interaction with the host:
- Saprophytes: bacteria that grow in soil and live on dead organic matter.
- Commensal bacteria: harmless microbes that live on the host without causing harm.
- Pathogenic bacteria: capable of causing disease.
- Primary pathogens: cause disease in healthy individuals.
- Opportunistic pathogens: take advantage of preexisting conditions (like weakened immune systems) to cause disease.
- Infection routes include: endogenous (self-infection) and exogenous (cross-infection).
- Endogenous infection: commensal bacteria in one part of the body moving to another.
- Exogenous infection: transmission from another source.
Sources of Exogenous Infections
- Patients: transmission from patients suffering from an active disease to healthy individuals.
- Infected animals: zoonotic infections.
- Soil: saprophytic microbes present in soil, vegetation, and similar environments.
- Carriers: individuals harboring pathogens without showing clinical symptoms, hence capable of spreading infections to others; classified as convalescent, chronic, or healthy carriers.
Modes of Transmission
- Ingestion (food or water).
- Inhalation (respiratory tract).
- Trauma.
- Direct contact (skin-to-skin).
- Sexual transmission.
- Blood-borne transmission.
- Vector-borne transmission.
- Vertical transmission (mother-to-child).
Mechanisms of Infection
- Exposure: Initial contact with pathogens.
- Adhesion: Pathogens attach to host cells.
- Invasion: Pathogens enter host cells or tissues.
- Colonization: Pathogens multiply and establish themselves.
- Toxicity: Release of toxins, directly harming host cells or disrupting their functions. -Tissue damage can manifest as disease.
Microbial Toxins
- Microbial products directly harming tissues and altering host metabolism, often causing major symptoms.
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Exotoxins: Secreted toxins with enzymatic activity. They often cause illness (e.g. diphtheria, tetanus, cholera)
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Endotoxins: Components of outer cell wall of Gram-negative bacteria. Released upon cell death, stimulating potent inflammatory reactions.
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Classified by structure and function.
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Defense Mechanisms
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Innate (non-specific): Immediate responses (e.g., physical barriers, inflammation, phagocytosis, complement system, interferons).
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Adaptive (specific): Immune response adapted to particular pathogens (e.g., antibodies, T cells).
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Innate responses: immediate responses to infection.
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Innate, antigen-nonspecific defenses: local response, including phagocytes (macrophages, neutrophils), natural killer (NK) cells, dendritic cells, interferons, complement system, inflammation/fever, antimicrobial peptides (AMPs).
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Non-specific physical and chemical defenses: skin, mucous membranes, stomach acids, lysozyme in tears, expulsion (coughing, sneezing, vomiting, diarrhea).
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Adaptive, antigen-specific responses: antibodies and T cells.
Complement System
- The complement system is a crucial part of the innate immune system participating in the destruction of pathogens.
- Various pathways (classical, alternative, lectin) activate the complement cascade leading to the formation of the membrane attack complex (MAC) and a series of other crucial immune responses.
Phagocytes and Inflammation
- Phagocytes (such as macrophages and neutrophils) engulf and destroy pathogens, initiating an inflammatory response.
- Inflammation is a localized response following injury or infection, characterized by redness, swelling, heat, and pain; it's a crucial part of the body´s defenses.
Bacterial Pathogenesis
- Disease results from tissue damage caused by toxins or direct killing.
- Microbes can infect distant tissues.
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