Medical Microbiology Flashcards
Microbiological aspects of human and animal infections and infestations, with emphasis on their atiological agents
Clinical Microbiology
The study of the cause of a disease
Etiology
Antagonistic association between an organism and the metabolic substances produced by another
Antibiosis
Treatment of disease by chemical that kill cells, specifically thos of microorganisms or cancer
Chemotherapy
A broad branch of biomedical science that covers the study of all aspects of the immune system in all organisms
Immunology
The study of factors affecting the health and illness of populations
Epidemiology
Implies the presence of microorganisms in or on the body of the host
Infection
A state when the microorganism is successful in producing physiological or anatomical changes in the host
Disease
Disease caused by microorganisms or viruses
Infectious (contagious) disease
Microbial parasite
Pathogen
Causes disease only when the body’s defenses are compromised
Opportunistic pathogen
The outcome of host-prasite relationship depends on:
Pathogenicity of parasite
Resistance of the host to the parasite
Ability of the parasite to inflict damage on the host
Pathogenicity
A measure/degree of pathogenicity
Virulence
Pathogenicity varies widely, meaning?
The host-parasite interaction is dynamic
Constantly changing virulence of pathogen and resistance of host
Two properties required for the production of diseases by microorganisms
Must be able to metaboize and multiply in or upon host tissue
Must be able to resist host defense mechanisms
Toxic or destructive substances produced by the pathogen that directly or indirectly enhance infection leading to disease
Virulance factors
Virulence factors in pathogens
Toxins
Capsule
Enzymes
Two types of toxins
Exotoxins
Endotoxins
Heat-labile and acid-labile
Exotoxins
Examples of exotoxins
Tetanus toxin (Clostridium tetani) Botulinum toxin (C. botulinum)
Found in gram negative bacteria Heat stable Lipid portion of LPS Less toxic Highly pyrogenic
Endotoxins
An AB toxin produced by cells of Corynebacterium diptheriae
Diptheria toxin
May enable some bacteria to resist phagocytosis
Capsule
Example of capsule
Streptococcus pneumoniae
Enzymes
Caogulase
Lecithinase
Causes some bacteria to resist phagocytosis
Coagulase
Alpha Toxin
Lyzes RBCs and other tissues
Lecithinase
Indications of Virulence
Infectious dose
Lethal dose
Number of pathogenic cells or virions enough to establish or cause an infection that would lead to disease
Infectious dose
Expression of infectious dose
ID50 (medium infectious dose)
50% of the hosts ate infected
The dose that causes death
Number of pathogenic cell, virions, or amount of toxin required to kill the host
Lethal dose
Lethal dose expression
LD50
50% of hosts are killed
Steps of Pathogenesis
Exposure Adherence Invasion Colonization and Growth Toxicity/Invasiveness Tissue, Damage, Disease
Mode of transmission
Direct contact Indirect contact - via formites Vectors Airborne Food or Water
Sneeze Effects
Up to 8m
Can linger for 10 minutes
Cough Effects
Up to 6m
Can linger for 10 minutes
Portals of Entry
Skin
Mucous Membranes
Parenteral Routes
Examples of mucous membranes
Respiratory tract
Gastrointestinal tract
Genitourinary tract
Conjunctiva
Pathogen is able to enter into host cells or tissues, spread, and cause damage and disease
Invasion
Presence of bacteria in blood
Bacteremia
Bacteria able to multiply and produce toxins in the bloodstream and spreading in the body
Septicemia
Presence of virus in bloodstream
Viremia
Human defense mechanisms
Innate immunity
Acquired immunity
Non-specific resistance
Innate immunity
Adaptive immune response
Specific resistance
Acquired immunity
Innate immunity
First line of defense
Second line of defense
First line of defense
Skin
Mucous membranes
Secretions of skin and mucous membranes
Second line of defenses
Phagocytic leukocytes
Antimicrobial proteins
Inflammatory response
Fever
Adapative immunity
Third line of defense
Lymphocytes
Antibodies
Memory cells
