Chapter 13 Flashcards
Pathologic State
Results when the infection damages or disrupts tissues and organs. “I don’t feel good”.
Infectious Disease
The disruption of a tissue or organ caused by microbes or their products. For example, food poisoning or ebola.
Resident Biota
Microbes on the human body that has a stable, non-pathogenic relationship with the human host.
Sites that harbor a known normal biota
Skin, respiratory tract, GI tract, outer opening of urethra, external genitalia, vagina, external ear canal, external eye including lids and conjunctiva.
Microbial Antagonism
Bacterial biota benefit the human host by preventing the overgrowth of harmful microorganisms.
Endogenous Infections
Caused by biota that are already present in the body. Example- biofilm.
Pathogen
A microbe whose relationship with its host is parasitic and results in infection and disease.
True Pathogen
Capable of causing disease in a healthy person. Associated with a specific, recognizable disease.
Opportunistic Pathogen
Causes disease when host defenses are compromised.
Pathogenicity
Concept that describes an organism’s potential to cause disease. Become established in body parts not natural to them.
Factors that weaken host defenses/ increase susceptibility to infection
Old age, extreme youth, genetic defects in immunity and acquired defects in immunity (AIDS), surgery and organ transplants, organic diseases including cancer, liver malfunction, and diabetes, chemotherapy/immunosuppressive drugs, physical and mental stress, other infections.
Virulence
Degree of pathogenicity determined by its ability to establish itself in the host and cause damage.
Virulence Factor
Any characteristic or structure of the microbe that contributes to its virulence including ability to produce toxin, fimbrae, capsule. Adaptations used to invade and establish itself in host tissues.
Exogenous
Microorganism originating from source outside of the body.
GI Tract as Portal of Entry
Pathogens in food, drink, and other ingested subasances adapted to survive digestive enzymes and pH changes. Best known agents are enteric bacteria.
Infectious Agents that enter the skin
Common portal of entry including nicks, abrasions, and punctures. Some create their own passageway using digestive enzymes or bites.
Respiratory Portal of Entry
Includes the greatest number of pathogens due to the fact that structures in the respiratory tract have a continuous mucous membrane covering. Smaller cells and particles are inhaled more deeply.
Urogenital Portal of Entry
STDs account for nearly 4% of infections world wide. Not all are stis, some caused by displaced organisms.
Pathogens that infect during pregnancy and birth
Some microbes cross the placenta with an 80% fatality rate for syphilis. Some infections occur prenatally when the child is contaminated by the birth canal.
Infectious Dose (ID)
Smaller infectious dose, greater virulence. Infection only proceeds if ID is present.
Subclinical Dose
Numbers below infectious dose that do not result in infection.
Adhesion
A way for microbes to gain foothold on host tissue. Mechanisms of attachment include fimbrae, surface protein, and adhesive slimes and capsules for bacteria. Spikes for viruses. Hooks, suckers, and barbs for parasites.
Phagocytes
White blood cells that engulf and destroy pathogens with enzymes and antimicrobial chemicals. Strongest immune response.
Antiphagocytic factors
Used by some aggressive pathogens to avoid phagocytes. Include extracellular surface layer and some can survive inside phagocytes after ingestion.
Direct damage
Use exoenzymes or toxins to inflict damage.
Indirect damage
Excessive or inappropriate host response to damage.
Bacterial Toxin
Specific chemical product that is poisonous to other organisms.
Toxigenicity
The power to produce toxins.
Toxinoses
A variety of disease caused by toxigenicity
Toxemias
Toxinoses in which the toxin is spread by the blood from the site of infection. (tetanus and diphtheria)
Intoxications
Toxinoses caused by ingestion of toxins (botulism)
Exotoxins
Toxin secreted by living bacterial cell into infected tissue. Example-proteins with specific target are extremely powerful that can cause death.
Endotoxins
Shed from the outer membrane of gram negative cells. Example- lipopolysaccharide of the gram negative wall has systemic effect on tissues.
Process of Infection and Disease
Incubation (time from initial contact to first symptoms), prodromal stage (notable symptoms, vague feeling of discomfort), period of invasion (agent multiplies and exhibits high toxicity and becomes established in tissues), convalescent period (recovery period, patient’s strength and health gradually return)
Necrosis
Cell and tissue death
Localized infection
Microbe enters the body and remains confined to a specific tissue
Systemic infection
Spreads to several sites and tissue fluids, usually in the bloodstream
Focal infection
Caused when agent breaks loose from local infection and is carried to other tissues
Mixed infection
Several agents establish infection simultaneously at the infection site
Primary/Secondary infection
Infection according to sequence. Primary infection complicated by another secondary infection by a different microbe.
Sign
Any objective evidence of disease as noted by an observer. Ex) Rash & Fever
Symptom
The subjective evidence of disease as sensed by the patient. Ex) Pain
Syndrome
When a disease can be identified or defined by a certain complex of signs and symptoms.
How do pathogens vacate the host?
Shed or released from the body through secretion, excretion, discharge, sloughing.
Respiratory and Salivary Exit Portals
Most effective means by coughing, sneezing, talking, and laughing. Mucous, sputum, nasal discharge, and other moist secretions are media for escape.
Skin scales exit portal
Outer layer of skin and scalp are constantly sloughed off. Skin lesions and their exudates can act as portals of exit.
