anything that causes infection
number of new cases of an infectious disease in a given population
number of active cases of an infectious disease in a given population
stable incidence and prevalence of an infectious disease in a given population
sudden increase in incidence of an infectious disease in a given population
spread of an infectious disease beyond continental border
normal, harmless residence of local microorganism on mucous and cutaneous membranes
Define Resident Flora
live in or on the host and recolonize quickly if disturbed; symbiotic relationship with the host
Define Transient Flora
reside temporarily in or on the host
infections from resident flora gone wild when the host's immune system is compromised
Types of Infection
- Opportunistic Infections
- Virulent Infections
- Nosocomial Infections
What are Opportunistic Infections?
host's immune system is compromised; resident flora overgrow or move into a new location in the body
What are Virulent Infections?
microorganism that is consistently capable of causing disease
What is a Nosocomial Infection?
an infection from a hospital or clinical situation. They may be opportunistic or virulent in nature.
What are the types of Microorganisms?
How are Bacteria classified?
- by motility
What are the classifications of rigid bacteria?
- Unicellular forms
What are the classifications of unicellular rigid bacteria?
- Intracellular obligate parasites
- Free living bacteria
What are the classifications of free-living bacteria?
- Cocci --> round and immobile
- Bacilli --> rod shaped and may be mobile
- Spiral --> corkscrews
How are free-living bacteria classified?
- classified by their response to gram staining
- Gram Positive --> retain dye, dark purple
- Gram Negative --> resist stain, pink
- Acid Fast --> resist decoloration, red
What happens if bacteria get past the initial membrane defense and multiply and creat a colony in the host?
- Acute inflammatory response
- Phagocytic cells recruited
What happens if bacteria get past the 1st response?
bacteria will use the interstitial fluid, blood, and lymph networks to spread through the body
What happens if bacteria gets to the lymph nodes?
- Another attempt to clean them out
- If these fail then clumps of bacteria begin to flood the bloodstream
What are antibiotic?
cultural mechanism for discouraging microorganisms.
What are Viruses?
- genetic parasites composed of DNA or RNA and a capsule
- dependent on host cell for energy and for replication
What are the 2 mechanisms for invasion of the host cell?
- Adherence and endocytosis
- Adherence and injection of genetic material
What are the two ways for a virus to be released from a cell?
- release by budding from the host cell , host cell is not destroyed --> birth
- release by lysing the host cell, the host cell is destroyed -->scene from "Alien"
What are the ways of classifying viruses?
- DNA or RNA
- mode of replication
- capsule structure
- type of host cell
How do DNA viruses replicate?
- produce mRNA in the host cell nucleus and with the host cell's enzymes
- host cell's machinery is used to translate the viral mRNA's
- (herpes simplex)
What are the two ways that RNA viruses replicate?
- -->Positive Copy
- -->Negavie Copy
How does reverse transcriptase work?
- converts the viral RNA chromosome into viral DNA
- viral DNA is incorporated into the host cell's chromosome
- Viral proteins are produced from viral mRNA using the host machinery
How does positive copy RNA work?
Postive copy RNA is used as a direct template to make viral proteins and complementary negative RNA
How does negative copy work?
converted into a complementary positive RNA which is used to produce viral proteins or progeny chromosome
What are the treatments for viral infections?
- anti virals
What are Fungi?
- yeasts and molds
- nonphotosynthetic, eukaryotic protists that exist everywhere
What is good at cleaning up fungi?
Phagocytes especially neutrophils and some monocytes and eosinophils
What are the types of mycoses?
- Opportunistic mycoses
- Superficial mycoses
- Subcutaneous mycoses
- Systemic mycoses
What is an opportunisitc mycoses?
normal flora that become bothersome
What are superficial mycoses?
occur only on dead, keratinized tissue
What are subcutaneous mycoses?
occur in subcutaneous tissue due to trama
What are systemic mycoses?
usually caused by soil fungi that are inhaled
What are the four types of parasites?
- Nematohelminthes (round worms)
- Platyhelminths (flatworms, tapeworms)
What is the chain of transmission?
Reservoir --> Portal of Exit --> Mode of Transmission --> Portal of Entry --> Susceptible Victim
What are things that help the pathogen enter the host?
- Chemicals that promote adherence --> glycocalyx
- Mechanical structures that promote adherence --> pili and fimbriae
- Ability to attach to host proteins
- Ablitlity to attach to rough surfaces
What are things that help the pathogen get past the host's defenses?
- Bacterial enzymes that dissolve host blood or connective tissue proteins
- Encapsulation with a polysaccaride prevents fixation of complement and opsonization
- Survival inside phyocytes
- Endospore formation
- Production of IgA protease
What are the characteristics that harm or kill host cells?
- bacterial toxins kill host cells and induce inflammation
What are the host characteristics that affect infection?
- Epithelial barriers
- Nutritional status
- Chronic Illness
- Immune Status
- Poor Sanitation
- Crowded living conditions
- Improper handling of food
- Climate/Seasonal patterns
- Geographic location
What are the stages of infection?
What are the portals of entry for a pathogen?
- Direct Contact
What are the stages in a disease course?
- Incubation stage
- Prodromal Stage
- Acute Stage
- Convalescent Stage
- Resolution Stage
What are the 3 lines of defense?
- Physical Barriers
- Inflammatory Response
- Immune Response
What are the physical barriers?
- mucous membranes of GI, GU, and respiratory tracts by action of pH and or resident flora
- mucociliary blanket of respiratory passages
- flushing of tears, urine, bowel evacuation
- various substances in bodily secretions such as lysosomes in tears
- ongoing phagocytosis
What is the inflammatory response?
- Mast cell degranulation --> blood vessel inflammatory responses; phagocytic action of granulocytes
- fever -->heightened phagocytosis
- Plasma protein systems, Complement cascade, coagulation cascade, Kinin System
What is the immune response?
- Immunoglobulins, and T cytoxic lymphocytes
- Lymphocyte production of cytokines
- Protection through humoral and cell-mediated immune response and the production of antibodies and memory cells.