Chapter 14

• symbiosis: “to live together“
• Mutualism: A relationship in which both organisms benefit from the interaction.
• Commensalism: One benefits and other doesn’t benefit or be harmed
• Amensailism: One is harmed and the other isnt either harmed or benefited
• Parasitism: One benefits and other is harmed
• Microbiome of Humans: Organisms that colonize the body without normally causing disease. (Usually forms at birth)
• Resident Microbiota: Stay throughout life and are mostly commensal
• Transient Microbiota: Can’t persist in the body for long periods of time due to competition of body defense and physical/chemical changes
• Opportunistic pathogens: Normal Microbiota that cause disease under certain circumstances.
• Circumstances of Opportunistic pathogens: Introduction of normal microbe to diff site of the body, immune suppression, changes in normal Microbiota, and stressful conditions
• Reservoirs for infection: Sites where pathogens are maintained as a source of infection
• Three types of reservoirs: Animal,Human and Nonliving
• Zoonoses: Diseases that naturally spread from animal host to humans
• Acquire Zoonoses through: Direct contact with animal or its waste, eating animals, and bloodsucking arthropods
• Human carriers: Some individuals will show to be Asymptomatic carriers of the disease
• Nonliving Reservoirs: Soil, water, and food. Usually is contaminated by feces or urine
• Contamination: Presence of microbes in/on the body
• Infection: Organism evades body’s external defenses, multiples, and becomes established in the body
• Portal of entry: Includes Skin, Mucous membranes, and Placenta
• Skin: The outer layer of dead skin cells that protects the body from pathogens.
• Mucous Membrane: Line the body cavities that are open to the environment. Respiratory tract is the most common site entry.
• Placenta: Forms a barrier to block pathogens from growing fetus
• Parental route: Pathogens deposited directly into tissues beneath the skin or mucous membrane. Ex. Contaminated Needles
• Adhesion: Process by which microorganisms attach themselves to cells
• Adhesion factors: Pathogens use attachment proteins or Ligands
• The inability to make attachment proteins or adhesions render microorganisms avirulent
• Diseases: Results if the invading pathogen alter normal body functions also known as Morbidity
• Symptoms: Subjective characteristics of disease felt only by the patient
• Signs: Objective manifestations of disease observed or measured by others
• Syndrome: Symptoms + Signs that characterize a disease or an abnormal condition
• Asymptomatic/Subclinical: Infection lack symptoms but may still have signs of infection
• Etiology: Study of cause of disease
• Koch‘s postulates: 1. pathogen must be isolated 2. pathogen must be present in the disease 3. pathogen must be present in the disease
• Exceptions to Koch’s postulates: Inability to culture pathogen, cause is a combination of agents or other factors, and ethical considerations
• Pathogenicity: Potential of a microbe to cause a disease
• True/Primary Pathogens(obligate): Cause disease in healthy body
• Opportunistic Pathogens: Cause disease in immune-compromised or non-native body
• Virulence: Is the degree of pathogenicity
• Virulence factors: Extracellular enzymes, toxins, and antiphagocytic factors
• Extracellular enzymes: Pathogens can secrete this enzyme