Microbio Q3

• any disease causing microorganism
• 2 types: True/Primary pathogen & opportunistic pathogen

• can cause infection and disease in healthy people
• aka frank pathogen

can infect host only when immune defense is weakened

• pathogen is a parasite
• any organism that lives on or in another organism and is either metabolically dependent upon that organisms or derives nutrients from that organism
• have complex microbial interaction where one organism benefits from the association and the other organism is usually harmed or killed

a larger organism that supports the survival and growth of a smaller organism.

• often requires an extended relationship or coexistence between parasite and host .
• Is an example of symbiosis (the living together of organisms).

• Parasites have complex life cycles
• Parasitic infections usually involve several hosts:
• Definitive host
• Intermediate host(s)

• Maintains the mature form of the parasite
• Also, maintains the sexually reproductive form of the parasite

• Maintains the immature parasites
• The immature parasite usually undergoes various stages of maturation before being transferred to the definitive host

the ability of microbes to cause disease; the capacity of a pathogen to invade and harm a host

the steps involved in disease progression within the host

• the degree or intensity of pathogenicity
• -Is an important indicator of disease progression after infection by a pathogen
• -Is determined by factors associated with the pathogen (called virulence factors)

• A product of microbes that increases the invasiveness or pathogenicity of the organism
• contribute to tissue damage
• can be integral microbial cell components or secreted products e.g. LPS, capsule, fimbriae
• Can be secreted products; e.g. enzymes, toxins
• Can be genetic; e.g. presence of resistance genes

large segments of DNA that code for virulence factors; often acquired during horizontal transfer

the ability of microorganisms to establish an infection

the number of pathogens that infect 50% of hosts within a specified period of time

the ability of microorganisms to spread to adjacent tissues or other anatomical areas

the number of pathogens that kill 50% of hosts within a specified period of time; often associated with toxin production

• -signs
• -redness, runny nose, swelling, rash, coughing, pus formation, fever, vomiting, diarrhea

objective evidence of disease-characteristics of a disease that can be observed by someone else in addition to the patient

• -subjective evidence of disease
• -characteristics of disease that can only be determined [experienced] by the patient

• Pain
• Shortness of breath
• Nausea
• Sore throat
• Headache
• Malaise (discomfort)

• a nonspecific defense mechanism by the body in response to infection, injury or chemical irritation
• Characterized by:
• Rubor: redness-from blood accumulation
• Calor: heat-Warmth generated from the blood due to vasoconstriction
• Tumor: swelling (edema)-from the accumulation of fluid in surrounding tissue
• Dolor: pain-Soreness or tenderness from injury to local nerves
• Sometimes itching (pruritus)