Infection & Infectious Diseases

Host

provides life sustaining properties to infecting agent

Infection/Colonization

multiplication of the affecting agent within healthy cells/host

Microflora

normally inhibited bacteria of whatever the host may be (good/ causes no harm to host)

Commensalism

where both the bacteria and the host gain benefits

Mutulism

a relationship where the bacteria that need nutrition get it from the host but doesn’t harm the host

Parasitic

When the bacteria is taking more then they need from host and harming

Infectious Disease

cause harm to the host and can spread to others

Virulence

the disease causing potential of an organism (disease producing potential)

Pathogens

microorganism that can cause diseases (rarely found without disease)

Saprophytes

any organism that obtains its nutrients from dead or decaying organism

Opportunistic Pathogens

take the opportunity to infect when one of the body systems is weakend

Prions

• not common

• no genome

• infectious proteins

• can bind together do damage

• cause degenerative diseases in central nervous system

• mostly thrive in animals

Viruses

• smallest intracellular pathogen

• cannot reproduce without host

  • host’s cells normal metabolic activity makes new viruses

• Oncogenesis- can have the ability to cause cancer

• can have latent reaction

Bacteria

• Prokaryote (unicellular, no nucleus, and replicate on their own)

• Contain RNA/DNA

• Produce biofilms 

  • organization/colonization that provides protection and allows to thrive

• Cytoplasmic membrane and cell wall

• use hosts for food and shelter

• live in colonies

• classified by genus and species

• 3 shapes

  • spheres(cocci)

  • spiral(bacilli)

  • oblong/rod(spirilla)

Mycoplasmas

• smaller then bacteria

• no defined cell walls (harder to kill)

• pneumonia

Rickettsiacaea and Chlamydiacae

• have both bacterial and viral characteristics

• viral-like: obligate intracellular pathogens

• Bacterial-like: contain RNA/DNA and have cell walls

Fungi

• Has cell walls but different from bacteria 

• requires cooler temps then body temp

• few are capable of causing disease

• yeasts and molds

• infiltrate and bud

Parasites

• Protozoa: unicellular, complete cellular components

  • malaria, amebic dysentery, giardiasis

• Helminths: wormlike parasites, depend on and reproduce in host

  • roundworms, tapeworms

• Arthropods: include vectors of infectious disease (ticks, mosquitoes, flies, and ectoparasites) infects by direct contact or eggs on host (mites, lice, fleas)

Portals of Entry

• penetration

• direct contact

• ingestion

• inhalation

Virulence Factors

• Toxins- substances that break down the surrounding cells and tissues

• adhesion factors- what helps it adhere to the host

• Evasion factors- help it evade the host’s natural defenses

• Invasion factors- facilitate the infection

Clinical Course of Infection

1. Death: if infection goes above critical threshold

Infection in Clinical Course

exposure w/ no symptoms

Incubation Period in Clinical Course

replication w/ no symptoms

Prodromal in Clinical Course

symptoms are beginning to show and clinical threshold is passed

Acute Phase in Clinical Course

symptoms increase

Convalescent Phase in Clinical Course

Recovery phase where body starts to attack and break down the infection and symptoms begin to subside

Subclinical Phase in Clinical Course

body fights off infection before symptoms begin and reach clinical threshold

Resolution Outcome in Clinical Course

No more infection present

Chronic Disease Outcome in Clinical Course

Clinical Manifestations remain after infection is gone

Death Outcome in Clinical Course

infection goes above critical threshold

Clinical Manifestations of infection

fever, redness, swelling, anorexia, confusion

WBC for fighting infection

over 10,000

Diagnostics for Bacterial Infections

Gram-Stain and Culture & Sensitivity

Viral Infections Diagnostics

Antibody Titers and Polymerase Chain Reaction

Treatment of Infectious diseases

• primary prevention

• eradicate pathogen

• pharmacology

• antivirals

• antifungals