Infection

Helpfulness: +1
Set Details Share
created 5 years ago by chaneasegarvey
586 views
show moreless
Page to share:
Embed this setcancel
COPY
code changes based on your size selection
Size:
X
Show:
1

Microbiology

  • the study of microorganisms or microbes
2

Microbes/Microorganism

  • very small living forms that are visible only with a microscope
  • includes:
    • bacteria
    • fungi
    • protozoa
    • viruses
3

Bacteria

  • classified as prokaryotic cells
  • they are very simple in structure
  • lacks nuclear membrane, but function metabolically and reproduce
  • complex cell wall structure
  • unicellular organisms that do not require living tissue to survive
  • vary in size, shape, and arrangement
  • divide by binary fission
4

Pathogens

  • the disease-causing microbes
  • often referred to as germs
5

Infectious Diseases

  • result from invasion of the body by microbes and multiplication of these microbes, followed by damage to the body
6

Bacilli

  • rod-shaped organisms
7

Spirals

  • includes spirochetes and spirilla
  • displays a coiled shape appearance
8

Cocci

  • spherical forms
9

Diplo-

card image
  • indicates pairs
  • ex: diplococci
10

Strep(to)-

card image
  • indicates chains
  • ex: streptococci
11

Staph(ylo)-

card image
  • indicates irregular, grapelike clusters
  • ex: staphylococci
12

Tetrads-

card image
  • refers to cells grouped in a packet or square of four cells
13

Palisade-

card image
  • refers to cells lying together with the long side parallel
14

Basic Structure of Bacteria

  1. Rigid Cell Wall
    • protects the microbe
    • provides a specific shape
    • two types of cell walls that differ in their chemical composition:
      1. gram-positive
      2. gram-negative
  2. Cell Membrane
    • located inside the bacterial cell wall
    • semipermeable membrane
    • selectively controls movements of nutrients in and out of the cell
  3. External Capsule or Slime Layer
    • found in some bacteria, not all
    • found outside the cell wall
    • offers additional protection
    • interferes with the phagocytosis by macrophages and WBCs in the human body
  4. Flagellae
    • one or more attached to the cell wall
    • provides motility for some species
  5. Pili or Fimbriae
    • tiny hairlike structures, found on some bacteria (usually gram-negative)
    • assists in attachment of bacterium to tissue and
    • transfer of genetic material (DNA) to another bacterium
  6. Cytoplasm
    • contains:
    • the chromosome
      • composed of one long strand of DNA
    • Ribosomes
    • RNA
    • Plasmids
      • DNA fragments that are important in the exchange of genetic info with other bacteria
  7. Bacterial Secretions
    • Toxins
      • two types:
        1. Exotoxins
          • usually produced by gram-positive bacteria
          • diffuse through body fluids
          • interferes with nerve conduction
          • stimulate antibody or antitoxin production
        2. Endotoxins
          • present in the cell wall of gram-negative organisms
          • released after bacterium dies
    • Enzymes
      • produced by some bacteria
      • source of damage to the host tissues or cells
  8. Spores
    • formed by several species
    • latent form of the bacterium with a coating that is highly resistant to heat and other adverse conditions
    • can survive long periods in sport state
    • cannot reproduce while in spore form
15

Enterotoxins

  • may stimulate the vomiting center and cause gastrointestinal distress
16

Binary Fission

  • a division of the cell to produce two daughter cells identical to the parent bacterium
  • replication varies from a few minutes to several hours (depending on the particular microbe)
17

Virus(es)

  • a very small obligate intracellular parasite
  • requires a living host cel l for replication
  • contains:
    • protein coat/capsid
      • comes in various shapes and sizes
      • changes relatively quickly
    • Nucleic Acid
      • provides methods of classification of viruses
      • DNA or RNA virus
      • some RNA-containing viruses contain reverse transcriptase enzyme to convert RNA to DNA
18

Virion

  • an extracellular virus particle
19

Active Viral Infection

  • virus attaches to host cell
  • viral genetic material enters the cell
  • viral DNA or RNA takes control of cell
  • Uses host's cell to synthesize viral proteins and nucleic acids
  • New viruses are assembled in cytoplasm of cell
  • Viruses released by lysis of host cell or by budding from host cell membrane
20

Latent Viral Infection

  • virus enters cell as with active infection
  • viral proteins are produced and inserted into membrane of the host cell. This may stimulate an immune response and destruction of host cell
  • Virus may reproduce actively if immune system is depressed
21

Chlamydia, Rickettsiae, and Mycoplasmas

  • obligate intercellular parasites
  • do not grow on artificial media
  • some similarities with both bacteria and viruses
  • lack some basic components
  • classified as bacteria
  • replicate by binary fission within host cell
22

Chlamydia

  • common cause of sexually transmitted disease
  • can result in infertility
23

Rickettsiae

  • gram-negative
  • very small intracellular
  • transmitted by insect vectors (lice, ticks)
24

Mycoplasmas

  • lack cell wall
  • cause of pneumonia
25

Fungi

  • eukaryotic organisms (contains nucleus)
  • found throughout environment
    • on animals, plants, humans, food
  • fungal or mycotic infection
    • from single-celled yeast or multicellular molds
  • only a few are pathogenic
    • cause primary infection on skin or mucous membranes but may spread systemically
26

Candida

  • a usually harmless fungus
  • usually present on the skin
  • may cause infection in the oral cavity
  • causative agent of thrush and vaginitis
27

Histoplasma

  • can cause neurologic disease
  • causes lung infection
  • transmitted by inhaling contaminated dust or soil particles
28

Pneumocystis Carinii

  • opportunistic organism causing pneumonia
  • has some characteristics of fungi and protozoa
29

Protozoa

  • eukaryotic
  • unicellular
  • motile
  • lack cell wall
  • many live independently, some live on dead organic matter, others are parasites living in or on another living host
  • the pathogens are usually parasites
30

Helminth/Worms

  • are not microorganisms
  • they are parasites
  • cause infections in humans
  • multicellular eukaryotic organisms
  • may be very small or 1 meter in length
  • may enter through the skin
  • can be transmitted by insects
  • often found in the intestines but may inhabit the lung and blood vessels throughout their life cycle
  • their life cycle:
    1. ovum
      • may be ingested in contaminated food or water
    2. larva
      1. may be ingested in contaminated food or water
    3. adult
  • usually diagnosed by observation of ova or eggs in stool specimens
  • infections are more commonly found in young children
31

Pinworms

  • ova inhaled in dust in fecally contaminated areas
32

Hookworms

  • larvae enter skin from fecally contaminated soil in tropical areas
33

Tapeworms

  • most common form
  • transmitted by larvae in undercooked pork
34

Ascaris

  • giant roundworm
  • ingested with food that has been grown in feces; contaminated soil or prepared with hands that have been in feces/contaminated soil
35

Prions

  • protein-like agents
  • transmitted by consumption of contaminated tissues
    • infected blood
    • ingestion of meat
  • induces proteins in the brain to undergo abnormal folding and change in shape
  • causes degenerative disease of the nervous system
36

Resident Flora

  • usually helpful in preventing other organisms from establishing a colony
37

Normal Flora

  • the mixture of bacteria normally found at a particular body site
38

Infection

  • occurs when a microbe or parasite is able to reproduce in or on the body's tissues
  • may occur sporadically, localized groups, epidemics, or pandemics
39

Endemics

  • continuous transmission within a population
40

Epidemic

  • higher than normal transmission or spread to a new geographical area
41

Pandemic

  • transmission has occurred on most continents
42

Reservoir

  • the source of infection
  • possible reservoirs:
    • a person with an obvious active infection in an acute stage
    • a person who is asymptomatic
    • an animal
    • contaminated water, soil, food, or equipment
43

Carrier

  • a person who may never develop the disease but still can transmit it
  • a person with subclinical signs of the disease
44

Subclinical

  • without clinical manifestations
  • very mild, with few or no clinical manifestations
45

Agent

  • the microbe causing the infection
46

Direct Contact (mode of transmission)

  • no intermediary
  • touching an infectious lesion
  • sexual intercourse
  • microbes may be in the blood, body secretions, or a lesion
47

Indirect Contact (mode of transmission)

  • involved intermediary object or organism
  • contaminated hand or food
  • fomite
    • inanimate object
    • ex: instruments, bed linen that carries organisms
48

Droplet Transmission (respiratory or oral)

  • occurs when respiratory or salivary secretions containing pathogens are expelled from the body
  • may be inhaled directly by another person close by
49

Aerosol Transmission

  • involves small particles from the respiratory tract that remain suspended in the air and travel on air currents, infecting any new host who inhales the particles
50

Vector-Borne (mode of transmission)

  • insect or animal serves as an intermediary host in a disease
51

Nosocomial Infections

  • infections that occur in health care facilities
  • 10%-15% of patients acquire an infection in the hospital
52

Interferons

  • proteins produced by human host cells in response to viral invasion of the cell
  • influences the activity of nearby host cells
  • stimulate the immune system
53

Factors That Decrease Host Resistance

  • age (infants and elderly)
  • genetic susceptibility
  • immunodeficiency of any type
  • malnutrition
  • chronic disease
  • severe physical or emotional stress
  • inflammation or trauma
  • impaired inflammatory responses
  • severe or multiple infections
54

Pathogenicity

  • the capacity of microbes to cause disease
55

Virulence

  • the degree of pathogenicity of a specific microbe
  • based on:
    • invasive qualities
    • toxins
    • adherence to tissue by pili, fimbriae
    • ability to avoid host defenses
56

Fatality Rate

  • the percentage of deaths occurring in the number of persons who develop the disease
57

Emerging Infectious Diseases

  • identified by a new or unique set of signs and symptoms
  • or by increased spread
58

Superinfections

  • multi drug-resistant forms of existing diseases
59

Infection Control (Two Approaches)

  1. Standard Precautions
    • used in all settings with all clients when body fluids may be exchanged
  2. Specific Precautions
    • clients diagnosed with a particular infection
    • used in addition to standard precautions
60

Universal Precautions

  • assume that all body fluids from all individuals are possible sources of infection
  • two levels:
    1. general for all individuals
    2. specific to known infections at specific sites in the body
61

To Break the Cycle of Infection

  • the res