Host-Microbe Relationships

Symbiosis/Mutualism

2 organism living together where both organism benefit (bees and flowers)

Commensalism

2 organism living together where no harm OR benefit to host

Parasitism

2 organism living together where host is harmed at the expense of the host

Normal/Resident Microbial Flora

Organisms that colonize a site for months/years. Not alarming to find on body sites of healthy individuals. Differs by body site.

Transient Microbial Flora

Organisms present at a site temporarily (ex. dirt on hands that can be washed off)

Carriers

Organism that can carry pathogenic organisms with symptoms. Capable of transmitting infection

Opportunist

residential flora that can cause disease when given the opportunity (damaged tissue, puncture, disturbed habitat, weakened/compromised immune system)

Iatrogenic Infections

Occurs as the result of medical treatment or procedures (ex. antibiotics, indwelling catheters, etc.)

Pathogenicity

ability of a microbe to produce disease in an organism

True Pathogens

microbes able to cause disease in healthy immunocompetent individuals

Immunocompetent Individuals

people who have a healthy, fully functioning immune system

Virulence

The severity of disease in an infected host

high virulence

a disease able to cause severe harm, tissue damage, or death

low virulence

a disease that only causes mild sickness or no signs of disease at all.

Invasion

penetrate and grow in host tissue

Dissemination

spread from site of infection to distant organs or tissues

Toxins

poisonous substances produced by organisms that interact with host cells, disrupting normal metabolism and causing harm

Exotoxins

Gram (+) AND Gram (-). Produced by and secreted by organism, Heat labile

Endotoxins

Gram (-) ONLY. Part of organism (LPS). Heat stable

Infection

eating/ drinking the pathogenic organism and having the organism produce toxins in the body

Intoxication

eating the toxin produced by bacteria in a food/ water source

Normal Flora found on the SKIN

Staphylococcus spp.

Normal Flora found in the MOUTH

Streptococcal spp.

Normal Flora found in the GI TRACT

Bacteroids spp.

Normal Flora found in the UPPER RESPIRATORY TRACT

Viridans Streptococci (alpha and non-hemolytic streptococci)