Infection Flashcards
Allergy’s
- Exaggerated response against noninfectious environmental substances
Hypersensitivity Reactions
- Inappropriate responses by the immune system
AutoImmunity
- Misdirected response against the body’s own cells
Alloimmunity
- Misdirected response against beneficial foreign tissues, such as transfusions or transplants
Factors Influencing Infection
-Communicability
- Ability to spread from one individual to another and cause disease
Ex. Measles and Pertussis spread very easily
-HIV has lower communicability
Factors Influencing Infection
-Immunogenicity
- Ability of pathogens to induce an immune response
Factors Influencing Infection
-Infectivity
- Ability of the pathogen to invade and multiply in host
Factors Influencing Infection
-Mechanism of Action
- Manner in which the microorganism damages tissues
Factors Influencing Infection
-Pathogenicity
- Ability of an agent to produce disease – depends on all of the above mentioned:
- communicability
- immunogenicity
- infectivity
- mechanism of action
Factors Influencing Infection
-Portal of Entry
- Route by which a pathogenic microorganism infects the host
- Direct Contact
- Inhalation
- Ingestion
- Insect “bites”
Factors Influencing Infection
-Toxigenicity
- Ability to produce soluble toxins or endotoxins
- factors that greatly influence virulence
Factors Influencing Infection
-Virulence
- Capacity of pathogen to cause severe disease
Classes of Infectious Microorganisms
- Bacteria
- Viruses
- Fungi
- Parasites
Pathogens Defense Mechanisms
-All Defenses
- Prevents Phagocytosis
- Changes surface antigens
- Hides
- Fast proliferation
- Produce Toxins
Pathogens Defense Mechanisms
-Changes surface antigens
- Adds surface antigens or causes major changes to surface antigens (antigenic Drift/Shift)
Antigenic Shift
- A major change in the genetic makeup of an organism, usually resulting from gene reassortment or occurring when different species share genetic material.
Ex. Influenza Virus Type A is the most common example of an organism that undergoes antigenic shift
Antigenic Drift
- A minor change in the protein marker or antigen on an organism.
- Ex. Influenza virus change from year to year
- Vaccinations against the virus have to be adapted annually to combat changes
Pathogens Defense Mechanisms
-Hides
- The pathogen hides inside the cell
Pathogens Defense Mechanisms
-Fast Proliferation
- Quickly multiplies to surpass the development of the protective response
Pathogens Defense Mechanisms
-Produce Toxins
- Produces toxins that destroy neutrophils
Pathogens Defense Mechanisms
-Prevent Phagocytosis
- Produce thick capsules of protein and carbohydrates to prevent phagocytosis
Pathogen
-Site of Entry
- Skin and mucous membrane
- Alimentary, GU and Respiratory Tracts
- Eyes and ears
Pathogen
-Route of Entry
- Direct Contact
- Inhalation
- Ingestion
- Vector bite
Pathogen
-Mechanism of Infection
- Adhesion
- Enzyme release
- Phagocytic escape
- Acid resistance
Pathogen for Each Entry Point
-Skin
- Chickenpox
Pathogen Entry Points
-Lungs
- Measles
2. TB
Pathogen Entry Points
-GU
- Gonorrhea
- AIDS
- Hepatitis B
- Yellow Fever
Infection
- Bacterial/Viral
- Clinical Manifestations
- Fever
- Body aches
- Lymph node enlargement
Infection
- Fungal
- Clinical Manifestations
- Itching
- Redness of skin
- Thrush
- Nail thickening
Infection
- Protozoal/Helminths
- Clinical Manifestations
- Itching
- Rash
- Diarrhea
- Fever
Bacterial Virulence and Infectivity
-Exotoxins
- Enzymes release during growth, causing specific responses
- Immunogenic (capable of producing immune reponse)
- Antitoxin production
Ex. Cytotoxins / neurotoxins / pneumotoxins / enterotoxins / hemolysins
Bacterial Virulence and Infectivity
-Endotoxins
- Lipopolysaccharides contained in the cell walls of GRAM NEGATIVE organisms
- PYROGENIC effects
- Increase capillary permeability further by activating anyphlatoxins
Bacterial Virulence and Infectivity
-Bacteremia or Septicemia
- Presence of bacteria in the blood as a result of a failure of the body’s defense mechanisms
- Usually caused by GRAM-NEGATIVE bacteria
Bacterial Virulence and Infectivity
-Gram-Negative Bacteria
- Release toxins into the blood that cause:
- Widespread Vasodilation - Tumor Necrosis Factor-Alpha (TNF-alpha)
- Produced by activated macrophages when exposed to endotoxins from GRAM-NEGATIVE bacteria (chachectin)
Segmented Neutrophils
- Mature WBC’s
Bands of Neutrophils
- Immature WBC’s
Left Shift
- Greater % of Immature (bands) than Segments (Mature) = severe prolonged infection
Infection
-Diagnostics
- Increased WBC count shows infection
2. Increased number of immature Leukocytes
WBC’s
-Normal Values
- WBC’s = 5-10
- Immature (bands) = 3-6%
- Mature (Segments) 50-62%
WBC’s
-Shift to the Left
- WBC’s = 15
- Immature (bands) = 10%
- Mature (Segments) = 65%
Viral Infection & Injury
-Overview
- Intracellular “parasites”
- Dependent on host cells
- No metabolism or incapable of independent reproduction
- Virion binds to receptors on the plasma membrane
- Spreads cell to cell
Viral Replication Process
- Virion binds to receptor site
- Penetration
- Uncoating
- Replication
- Budding
- Release of new infective virions
Cellular effects of Viruses
- Stops DNA, RNA, and Protein Synthesis
- Disrupts lysosomal membranes
- Fusion of host cells, producing giant cells
- Alteration of antigenic identity, causing immune system attack
- Transformation of host cells into cancerous cells
- Promotion of secondary bacterial infections in tissues damaged by viruses
Fungal Infection & Injury
-Overview
- Large w/ thick cell walls
- Eukaryotes
- Exist as:
- Single-celled yeasts
- Multi-celled molds
- Both yeasts and molds (dimorphic)
Molds
- Filamentous fungi grow as multinucleate, branching hyphae, forming a mycelium
(Ex. Ringworm)
Yeasts
- Yeasts grow as ovoid or spherical; single cells multiply by budding and division
(Ex. Histoplasma)
Fungal Infection & Injury
-Actions
- Adapt to host environment
- Wide temperature variations, digest Keratin, low oxygen - Suppress immune defenses
- Low WBC’s promote fungal infection
WBC’s and Fungal Infection
- Low WBC’s promote fungal infection
Fungal Infection & Injury
-Mycoses
- Disease caused by fungi
- superficial
- deep
- opportunistic
Fungal Infection & Injury
-Dermatophytes
- Fungi that invade the skin, hair, or nails are known as dermatophytes
- Disease they produce are called tineas (ringworm
- Tinea capitis, tinea pedis, and tinea cruris - INTENSE ITCHING
Infection Treatment
-Vaccines (GOALS)
- GOAL: induce long-lasting protective immune responses that will not results in disease in healthy recipient
Infection Treatment
-Vaccines -(Types)
- Attenuated organism
- Killed organisms
- Recombinant viral protein
- Bacterial antigens
- Toxins
Infection Treatment
-Antimicrobials
- Inhibit synthesis of cell wall
- Damage cytoplasmic membrane
- Alter metabolism of nucleic acid
- Inhibit protein synthesis
- Modify energy metabolism
Antibiotic Therapy
-Penicillin
- For GRAM-POSITIVE cocci
Antibiotic Therapy
-Aminoglycoside
- For GRAM-NEGATIVE aerobes
Antibiotic Therapy
-Metronidazole
- For ANAEROBES
Antibiotic-Resistant Microorganisms
-MRSA
- Methacillin-resistant Staphylococcus aureus
Antibiotic-Resistant Microorganisms
-VRE
- Vancomycin-resistant enterococcus
Antibiotic-Resistant Microorganisms
-PRSP
- Penicillin-resistant Streptococcus pneumococci
Antibiotic-Resistant Microorganisms
-CDAD
- Clostridium difficile-associated diarrhea
Resistant Bacteria
-Traits
- Produce Enzymes that:
- Inactivate the antimicrobial
- Alter cell metabolism
- alter cell permeability
Prokaryotic Cells
- Prokaryotic cells do not have nuclei, which are partitioned by an intracellular membrane
- DNA forms one main coil in the cell cytoplasm
Ex. Bacteria
RNA Viruses
- Replicated their genetic material in the cytoplasm of the infected cell
- EXCEPTIONS: influenza and retroviruses
DNA Viruses
- Require the DNA to enter the nucleus and use the cell’s DNA polymerases to replicate
- EXCEPTION: poxviruses
Poxviruses
-replication
- provide their own DNA polymerase and replicate their DNA in the cytoplasm of the infected cell
Retrovirus
-Replication
- Convert their RNA genetic information to DNA using an enzyme contained in the virion, REVERSE TRANSCRIPTASE
Toxoids
Purified toxins that have been chemically detoxified without loss of immunogenicity
Attenuated Viruses
-Vaccines
- Contain live viruses that are weakened
- Attenuated viruses can establish life-threatening infections in individuals whose immune system are congenitally deficient or suppresed
Bacteremia
- Bacteria in the blood
Systemic Signs and symptoms of Septicemia
- Fever
- Massive vasodilation
- causes decrease in BP
Warm to touch / flush / BP low / tachycardic /
Classic S/S of a Pt going Septic?
- Caused by Gram-negative toxins
- Massive vasodilation
- Warm / flush / hypotensive / tachycardic / Confusion due to decreased oxygen to brain