Chapter 14: Host-microbe Disease Relationship and Disease Process Flashcards
Mutualism
Both organisms benefit
Parasitism
One benefits, one is negatively impacted
Commensalism
One is benefitted, one isn’t impacted
Host invasion
Contamination: microbes are present
Infection: microbes multiply
Disease: microbes causes disruption of host function/health
Pathogenicity
Capacity to cause disease
Virulence
Intensity/ strength of disease
Virulence factors
Physical feature or chemical produced by microbes that increases strength of disease
Attenuation
Weakening of pathogen so it is no longer harmful or causes disease, but still capable of causing an immune response (idea behind vaccines)
Resident microflora
Always present
Transient microflora
Temporary
Sterile body sites
Internal tissues and organs: - middle ear - sinuses - internal eye - bone marrow - muscles - glands - organs - circulatory system - brain and spinal cord - ovaries and testes Body fluids: - blood - cerebrospinal fluid - saliva prior to secretion - urine in kidneys and bladder - semen prior to entry into urethra
Opportunism
Microbes can cause infection if given the right conditions
- host defense failure (immunocompromised)
- microbes introduced to unusual locations
- microflora disturbances
Infectious diseases
Caused by infectious agent
- bacteria, virus
Non infectious disease
Caused by other sources like mutations
Communicable disease
Contagious
Non communicable
Not contagious
- ear infection
Contagious
Easily spread
Infectious + communicable
Disease process
- Enter the host
- Attach to host cell
- Grow/colonize/multiply in host
- Disrupt host health, may produce enzymes/toxins or invade tissues
- Evade host immune system
Adherence factor
Attachment polo, Fimbrae, glycocalyx
Enzymes as virulence factors
Microbes may release damaging enzymes
- coagulase causes a clot around bacteria, streptokinase dissolved the clot
- hyaluronidase dissolves “glue” between cells
Toxins
Poisonous substances that are categorized by how they’re released from the cell
Endotoxins
Exist inside microbial cell, can cause fever, shock, possible host death
- G- bacteria have LPS in cell membrane (toxin released when cell dies)
Exotoxins
Made to be secreted, very potent, usually proteins, often cause damage to specific tissues
- G+
Leukocidin
Exotoxins that targets WBCs
Hemolysins
Exotoxins that target RBCs
Neurotoxins
Exotoxins that target nervous tissue
- very serious, often fatal ex. Botulism
Enterotoxins
Exotoxins that target gut bacteria
- usually food poisoning
Toxoid
Toxin that’s been neutralized so that it doesn’t cause disease but will mount an immune response
- tetanus vaccine
Sign
Characteristic of a disease that can be observed by examining the patient
Symptom
Characteristic of disease that can be observed or felt only by the patient
Syndrome
Combination of signs and symptoms that occur together and are indicative of a particular disease or abnormal condition
Sequelae
After effects of disease
Acute disease
Develops rapidly and runs its course quickly
- measles and colds
Chronic disease
Develops more slowly and is usually less severe, persists for a long indeterminate period
- tuberculosis and leprosy
Subacute disease
Intermediate between acute and chronic
- gingivitis
Patent disease
Periods of inactivity before signs and symptoms or between attacks
- herpes simplex
Local infection
Confined to a specific area of the body
- boils, bladder infections
Systemic infections
Affects most of the body & pathogens are widely distributed in many tissues
- typhoid fever
Bacteriemia
Bacteria in the blood
Viremia
Viruses in the blood
Primary infection
Initial infection in a previously healthy person
- usually acute
Secondary infection
Follows primary, especially in individuals weakened by primary infection
- someone weakened by cold (primary) may then get a middle ear infection (secondary)
Superinfection
Secondary infection that results from the destruction of normal microflora and often follows the use of broad spectrum antibiotics
Disease stages
Incubation: time between infection and appearance of signs and symptoms
Prodromal: short period where nonspecific, mild symptoms (headache) appear
Invasive: period where typical signs and symptoms are felt, disease is at acme
Decline: immune system and treatment overcome pathogen, microbes numbers drop, feel better
Convalescence: healing from tissue damage, body gains strength
