Pathogens: Types and Transmission

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Questions and Answers

Which pathogen type is primarily transmitted through insect vectors?

  • Protozoa
  • Bacteria
  • Rickettsia (correct)
  • Virus

What is the primary target of antibiotic medications?

  • Fungi
  • Bacteria (correct)
  • Viruses
  • Helminths

If a link in the chain of infection is broken, what is the most likely outcome?

  • The infection will be completely eradicated
  • The infection will be prevented or controlled (correct)
  • The infection will progress more rapidly
  • The infection will spread to more people

Which process involves using a high heat or chemical agent to eliminate all forms of microbial life, including bacterial spores?

<p>Sterilization (D)</p> Signup and view all the answers

A patient presents with severe intestinal discomfort and several eggs are observed in their stool sample. Which of the following is the most probable cause?

<p>Helminth infection (C)</p> Signup and view all the answers

Which pathogen is characterized by its ability to be treated with antibiotics?

<p>Bacteria (D)</p> Signup and view all the answers

What is the primary function of standard precautions in infection control?

<p>To prevent the transmission of pathogens from one individual to another (D)</p> Signup and view all the answers

Which of these represents a break in the chain of infection?

<p>A healthcare worker washing their hands after contact with a patient (B)</p> Signup and view all the answers

Which organization is known for defining the guidelines for standard precautions?

<p>Centers for Disease Control and Prevention (CDC) (C)</p> Signup and view all the answers

A patient who presents with severe diarrhea and dehydration after drinking from a pond is MOST likely infected with which type of pathogen?

<p>Protozoa (B)</p> Signup and view all the answers

The use of an antiseptic is BEST exemplified by which of the following?

<p>Applying an iodine solution to clean a skin wound (B)</p> Signup and view all the answers

A healthcare provider notes a sample of eggs in a patient's stool sample. What type of pathogen is MOST LIKELY responsible for these symptoms?

<p>Helminth (A)</p> Signup and view all the answers

Which of the following is the most accurate description of sterilization?

<p>The process of eliminating all forms of microbial life, including spores (D)</p> Signup and view all the answers

What structural feature primarily differentiates fungal cells from both plant and animal cells?

<p>Presence of chitin in the cell wall (C)</p> Signup and view all the answers

How does dimorphism in certain fungi contribute to their survival and pathogenicity?

<p>It allows them to switch between yeast-like and mold-like forms depending on environmental conditions. (C)</p> Signup and view all the answers

What is a key characteristic of the reproduction of MANY fungi that is important in their pathogenicity?

<p>They have unique mechanisms for spore production that aid their spread. (C)</p> Signup and view all the answers

What is a characteristic feature of Rickettsia regarding their growth and replication?

<p>They are obligate intracellular bacteria that replicate in the host's cytoplasm. (A)</p> Signup and view all the answers

What is vasculitis, which can result from some Rickettsia infections?

<p>Inflammation of the blood vessels (C)</p> Signup and view all the answers

Which structural component is unique to bacteria and is composed of peptidoglycan?

<p>Cell Wall (D)</p> Signup and view all the answers

What is the primary function of the viral capsid?

<p>To protect the viral nucleic acid and facilitate attachment to host cells (D)</p> Signup and view all the answers

What is a key difference in cellular organization between bacteria and fungi?

<p>Bacteria are prokaryotic, while fungi are eukaryotic (C)</p> Signup and view all the answers

Which of these characteristics is exclusive to viruses?

<p>Presence of a capsid composed of protein subunits (B)</p> Signup and view all the answers

Which of the following forms of fungi is characterized by a network of hyphae forming a mycelium?

<p>Mold (A)</p> Signup and view all the answers

What is the key difference in genetic material between some viruses and other types of organisms?

<p>Some viruses can have their genetic material be single-stranded RNA (A)</p> Signup and view all the answers

Which of these structures is associated with bacteria's ability to move or attach to surfaces?

<p>Flagella, pili, and fimbriae (B)</p> Signup and view all the answers

What is the function of the envelope that surrounds some viruses?

<p>To contribute to virulence and protection from the host's immune system (B)</p> Signup and view all the answers

Flashcards

Bacteria

A single-celled organism that can cause disease. Bacteria are prokaryotic, meaning they lack a nucleus and other membrane-bound organelles. They are typically treated with antibiotics.

Rickettsia

A type of pathogen that lives inside the cells of other organisms.

Sterilization

The process of destroying all microorganisms, including spores, on a surface or object. Sterilization typically involves using heat, chemicals, or radiation.

Protozoa

A parasitic organism that can cause a variety of diseases, including malaria and giardiasis.

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Helminths

These are multi-celled organisms that can cause a variety of diseases, including tapeworms and hookworms.

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Disinfection

A method of reducing the number of microorganisms on a surface or object. This is less thorough than sterilization.

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Antisepsis

A process that reduces the number of microorganisms on living tissue, like skin. This is less powerful than disinfection.

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What are Standard Precautions?

A set of precautions used in healthcare settings to prevent the spread of infection. These are implemented for all patients.

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Fungal Dimorphism

Fungi can exist in two forms: yeast-like, which are single-celled and round, and mold-like, which are multicellular and filamentous. This adaptability allows them to thrive in different environments.

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What is Chitin in fungi?

Chitin is a strong and rigid substance found in the cell walls of fungi. It makes them different from plant and animal cells.

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What are Rickettsia?

Rickettsia are small, gram-negative bacteria that require a host cell to survive and replicate.

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What makes Rickettsia's structure unique?

Rickettsia lack a cell wall and are smaller than most bacteria. This makes them unique among bacteria.

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How are Rickettsia transmitted?

Rickettsia are transmitted by vectors, like fleas, lice, or ticks. These vectors carry the bacteria and spread them to new hosts.

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What are bacteria?

Organisms lacking a nucleus and other membrane-bound organelles. These single-celled organisms are grouped into various shapes, including cocci (spherical), bacilli (rod-shaped), spirilla (spiral), and vibrios (comma-shaped).

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What is a bacterial cell wall?

A rigid outer layer that surrounds the plasma membrane of bacteria and provides structural support and shape. It's primarily composed of peptidoglycan and is critical for classifying bacteria based on its structure.

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What are plasmids?

Small, circular DNA molecules found in many bacteria. They replicate independently of the bacterial chromosome and often carry genes for resistance to antibiotics or other traits.

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What are viruses?

They are obligate intracellular parasites, meaning they can only reproduce inside host cells. Their structure typically consists of a core of nucleic acid (DNA or RNA) enclosed in a protein coat called a capsid.

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What is a capsid?

The protein coat surrounding the nucleic acid core of a virus. It is made up of repeating protein subunits called capsomeres, which protect the genetic material and facilitate attachment to host cells.

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What is chitin?

A tough polysaccharide found in the cell walls of fungi. It provides structural support and helps protect the fungus from its environment.

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What are yeasts?

Fungi that are single-celled. They reproduce asexually through budding, creating copies of themselves.

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What are molds?

Multicellular fungi that form a network of filaments called hyphae. Hyphae grow and branch out to form a complex structure called a mycelium.

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Study Notes

Pathogen Type, Structure, Diseases Caused, and Mode of Transmission

  • Bacteria: Single-celled prokaryotic organisms, often with cell walls. Diverse shapes (cocci, bacilli, spirilla, vibrios). Cell walls composed of peptidoglycan; variations (Gram-positive/Gram-negative) affect antibiotic susceptibility. Internal structures may include plasmids, ribosomes, storage granules, flagella, pili, and fimbriae. Diverse range of diseases, including pneumonia, strep throat, and food poisoning. Transmission varies, often through direct contact, contaminated food/water, or airborne droplets.
  • Virus: Non-cellular, obligate intracellular parasites. Consist of nucleic acid (DNA or RNA) core surrounded by a protein coat (capsid). Some have an envelope. Single-stranded or double-stranded nucleic acid. Some viruses have RNA genomes that are reverse-transcribed to DNA (e.g., retroviruses). The capsid is formed from repeating protein subunits called capsomeres. Genetic material varies widely in size and complexity. Causes a wide range of diseases, including influenza, HIV, and COVID-19. Transmission varies; often through respiratory droplets, direct contact, and contaminated surfaces.
  • Fungi: Eukaryotic organisms. Cell walls contain chitin. Can be unicellular (yeasts) or multicellular (molds and mushrooms). Moulds have a network of filaments called hyphae that form a mycelium. Some exhibit dimorphism, existing as yeast-like or mold-like cells. Causes various diseases, including ringworm, athlete's foot, and yeast infections. Transmission often occurs through skin contact or inhalation of fungal spores.
  • Rickettsia: Small, gram-negative, bacteria-like organisms. Obligate intracellular bacteria. Lack a cell wall, smaller than most bacteria. Unique life cycle requiring host cells for replication and transmission. Causes diseases like typhus and Rocky Mountain spotted fever. Transmission involves insect vectors (e.g., ticks, lice, fleas). Pathogenicity mechanisms: They rely on host cells for replication and produce some of their own proteins, but mostly use host cell machinery. Infection can lead to vasculitis, interfering with many bodily processes.
  • Protozoa: Single-celled eukaryotic organisms. Causes various intestinal and other diseases, including malaria and amoebiasis. Transmission occurs through ingestion of contaminated food/water, or insect vectors (e.g., mosquitoes).
  • Helminth: Parasitic worms. Causes diseases like tapeworm and roundworm infections. Transmission occurs via ingestion, often through contaminated food/water.

Pathogen Spread by Insects

  • Rickettsia (e.g., fleas, lice, ticks)

Treatable Microorganisms with Antibiotics

  • Bacteria

Chain of Infection

  • Infectious Agent: Pathogen causing the disease.
  • Reservoir: Place where the infectious agent lives and grows (e.g., human, animal, food).
  • Portal of Exit: Route out of the reservoir (e.g., respiratory tract, skin lesion, wound).
  • Mode of Transmission: How the agent moves from reservoir to new host (e.g., contact, droplets, vectors).
  • Portal of Entry: Method by which the pathogen enters a new host (e.g., respiratory tract, broken skin, mouth).
  • Susceptible Host: Host whose immune system cannot fight the agent.

Breaking the Chain of Infection

  • Interrupting any step in the chain stops transmission.

Definitions and Cleaning Agents

  • Antisepsis: Reducing the number of microorganisms on living tissue. Example cleaning agent: Alcohol, hydrogen peroxide.
  • Disinfection: Reducing the number of microorganisms on non-living surfaces.. Example cleaning agent: Bleach, quaternary ammonium compounds.
  • Sterilization: Eliminating all microorganisms, including spores. Example cleaning agent: Autoclaving (steam under pressure), dry heat.

Purpose of Standard Precautions

  • To prevent the spread of infectious agents in healthcare settings.

Standard Precautions and the Defining Organization

  • Centers for Disease Control and Prevention (CDC)

Likely Pathogen for Diarrhea and Dehydration from Pond Water

  • Protozoa

Likely Pathogen for Weight Loss, Intestinal Discomfort and Eggs in Stool

  • Helminth

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