microbiology

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• Microbial infection

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WHAT IS INFECTION?

• Infection is the invasion of body tissues by dise
  ase-causing agents, their multiplication, and the
  reaction of host-tissues to the infectious agents
  and the toxins they produce. Infectious disease,
  also known as transmissible disease or communicabl
  e disease, is illness resulting from an
  infection.
• Hosts can fight infections using their immune
  system. Mammalian hosts react to infections with
  an innate response, often involving inflammation,
  followed by an adaptive response.

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WHAT CAUSES INFECTIONS?

• Infections are caused by infectious
  agents including 
• Bacteria
• Viruses
• Fungi (ringworm)
• Protozoa
• Macroparasites (nematodes, tapeworms, helminths)

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Types of infectious diseases
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PROPERTIES OF INFECTIOUS AGENTS

• Pathogenicity
• Virulence
• Specificity
• Organotropicity

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PATHOGENICITY

• Pathogenicity is a specific sign of the
  pathogen, its potential to cause a specific
  infectious process under favorable conditions. On
  this basis, all states of microbes are subdivided
  into pathogenic, opportunistic and saprophytes.
  Pathogenicity and virulence are different
  concepts. A microorganism is considered virulent
  if it, when introduced into the animal's
  organism, even in small doses, causes the
  development of an infectious process.

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VIRULENCE

• Virulence is the degree of pathogenicity of a
  particular microorganism, i.e. this is an
  individual characteristic. Virulence is a
  quantity that is measured (e.g., minimum lethal
  dose DLM, median lethal dose LD50).

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SPECIFICITY

• Each infectious disease causes a specific
  pathogen. So, the causative agent of plague
  causes plague, cholera - cholera, etc. Infections
  (for example, purulent-inflammatory processes)
  caused by various microbes are known. On the
  other hand, one causative agent (for example,
  streptococcus) is capable of causing various
  lesions.

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ORGANOTROPICITY

• Organotropicity is the defeat of cells, tissues
  and organs that are most suitable for their
  biochemical properties for life support of this
  type of microorganism.

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VIRULENCE FACTORS

• 1. Adhesion to cells
• Many bacteria for infection of certain cells of
  the body, for example, intestinal epithelium
  should attach to them. It was found that a large
  number of host cell molecules, in particular, and
  the receptors of bacteria (proteins of the outer
  bacterial membrane) are involved in this process.

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VIRULENCE FACTORS

• 2. Invasiveness
• Some virulent bacteria produce proteins that
  destroy cell membranes or stimulate phagocytosis
  of host cells. These virulence factors allow
  bacteria to enter the host's body through the
  layers of cells that come in contact with the
  pathogen, whether they are cells of the outer
  covers of plants or animals or layers of
  epithelium of internal organs.

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VIRULENCE FACTORS

• 3. Colonization is the process of multiplication
  of microbes at the site of adhesion. Colonization
  provides the accumulation of microorganisms to
  such a critical concentration that can cause a
  pathological effect.

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VIRULENCE FACTORS

• 4. Suppression of the immune response
• Many bacteria release virulence factors that
  inhibit the body's immune system. For example,
  bacteria secrete proteins that attach to host
  antibodies. Another type of substance that
  inhibits the immune response is the
  polysaccharide capsule surrounding the cell.
  These polysaccharides complicate phagocytosis of
  bacteria by specialized cells of the immune
  system (macrophages) and lymphocytes.

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VIRULENCE FACTORS

• 5. Toxins
• Many virulence factors are proteins that the
  pathogen produces and then secretes into the
  environment and which causes damage to the host
  tissues. For example, with food poisoning it is
  the toxins that cause the symptoms of the disease.

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BACTERIAL TOXINS
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BACTERIAL TOXINS
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FORMS OF INFECTION PROCESSES

• Infectious disease

• Bacteriocarrier
• Chronic (presence of pathogens for several months
  or even years)
• Transitory (short-term (most often - once)
  excretion of the pathogen in the absence of
  clinical manifestations of the disease)
• Sharp (a consequence of a recent illness)

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COMMON ORAL INFECTIONS
Gingivitis
Periodontal Disease
Dental Caries
Canker Sores

• Oral Herpes

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REASONS OF ORAL INFECTIONS

• injuries
• a lack of vitamins and trace elements
• a general decrease in immunity
• allergic reactions
• infections
• the presence of tartar deposits
• poor hygienic condition of the cavity

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BIOLOGICAL RESEARCH METHODS

• Biological research methods are aimed at
  determining the presence of pathogen toxins in
  the test material and on the detection of the
  causative agent. Methods include infecting
  laboratory animals with the test material,
  followed by isolation of a pure pathogen culture
  or establishing the presence of a microbial toxin
  and its nature. The method is highly sensitive,
  can be used in the early stages of the disease,
  but is not always available, expensive,
  long-lasting, unsafe.

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OBJECTIVES OF BIOLOGICAL METHOD

• 1. Diagnosis of infectious diseases.
• 2. Identification of pure culture.
• 3. Definition of virulence.
• 4. Isolation and identification of exotoxins.
• 5. Cultivation of viruses.
• 6. Reception of immunopreparations.
• 7. Checking the harmlessness and effectiveness of
  medications (including chemotherapy drugs,
  immunopreparations) and others.

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STAGES OF BIOLOGICAL METHOD

• 1. Material intake.
• 2. Material processing.
• 3. The choice of a laboratory animal.
• 4. Infection of animals by one of the methods.
• 5. Registration of signs of illness of the
  infected animal or its death.
• 6. Intravital sampling of material from the
  animal and carrying out bacteriological and
  serological studies, setting an allergic test.
• 7. Autopsy, study of pathoanatomical and
  pathomorphological pattern. Preparation of
  smears-prints from internal organs.
• 8. Identification of the selected culture.
• 9. Conclusion on the results of the study.

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Standard Precautions

• are defined as the basic work practices
  required to provide a minimum level of infection
  control. They are recommended for the treatment
  and care of all clients regardless of the
  clients diagnosis or presumed infectious status.
  
• Why would this be so?? Activity Question.

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Standard Precautions. Continued

• Work practices that are used in all circumstances
  to achieve a basic level of infection control
• They are aimed at reducing the spread of
  infections
• They apply to all clients regardless of known
  infectious status
• They are aimed to protect the Health Care Worker
  as well as the client.

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Standard Precautions. Continued

• Used for all clients, regardless of infectious
  status
• Used when risk of exposure to blood or body
  fluids
• Blood (including dried blood)
• All other body fluids, secretions excretions
• Open wounds/broken skin
• Mucous membranes

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Standard Precautions. Continued

• Apply to
• Hand hygiene
• Personal protective equipment (PPE)
• Immunisation
• Aseptic technique for wound care
• Safe handling of sharps

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Standard Precautions.

• HAND HYGIENE
• Is the most important
• precaution to
• prevent the
• transmission of
• infection

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Additional Precautions

• Are used in ADDITION to Standard Precautions.
• They are used when Standard Precautions are not
  enough to prevent transmission
• of organisms.
• They are work practices that interrupt the spread
  of a known infection eg gastroenteritis

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Additional Precautions. Continued

• Address the different ways in which organisms are
  transmitted
• Airborne
• Droplet
• Direct / Indirect Contact

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Risk Management

• Look after your own safety
• Do not place others at risk. You must report
  document any outbreaks or suspicions of outbreak
• Use PPE and clothing
• Comply with policies, procedures, instructions,
  practices and legislative requirements of the
  organisation

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Conclusion

• Principles of infection control apply in all
  settings
• Standard Precautions should be applied to all
  work practices
• Additional precautions apply when preventing the
  transmission of known infections

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