P. P. H. P. V. C. M
- Any disease producing agent or microorganism
- Ability to produce pathogenic changes or disease
- Speed of reproduction
- Extent of tissue damage
- Production of a toxin
- Any organism capable of supporting nutritional and physical growth requirements of another
- Organism that lives within, upon, or at the expense of another organism
- Only the infecting organism benefits from relationship
Parasite: affected by...
- Disease producing potential
- Degree of pathogenicity of an organism
Properties that influence Virulence
- Strength of adhesion molecules
- Ability to secret enzymes or endotoxins
- Ability to inhibit or evade actions of WBCs and chemical mediators
- Microorganisms present without host interference or interaction and without symptoms to a host
- infection is not present.
- Normal bacterial flora
- Colonization with organisms that persist for a long period of time
- In many cases a mutual relationship exists, where the host is not adversely affected.
- They can be pathogenic when/if the host's immune system becomes compromised.
Definition of infection
- Presence and growth of a microorganism that produces tissue damage
- Accompanied by inflammation
Extent of infection
- Number and virulence of the organism
- Ability of body to contain or destroy them.
Forms of infection
A. C. S. S. N. O
- Subclinical or subacute
- Infection that appears suddenly
Stages of Acute infection
I. P. A. C. R
- Prodromal period
- Acute stage
- Convalescent period
- From time pathogen enters until appearance of first symptoms
- Varies from pathogen to pathogen
influence on Incubation
- General health of the host
- How it enters the host
- Infectious dose of the pathogen
- Symptoms indicative of an approaching disease.
- May only be a vague sense of malaise
- Hallmark of most infectious diseases is fever.
- Actively have the disease
- Signs and symptoms present
- Period of recovery
- Containment of infection
- progressive elimination of the pathogen
- repair of damaged tissue
- Resolution of associated symptoms
- Total elimination of the pathogen
- No residual signs or symptoms of disease
- An infection having a protracted (long, drawn out) course
- Sometimes has an irregular course
Subclinical or subacute infection
- progress from infection to resolution without clinically apparent symptoms
- Infection made possible by a primary infection that lowers the host's resistance
- Ie: bacterial pneumonia following influenza
- Infection acquired during hospitalization
- Also known as hospital acquired infetion
- Number one Type is UTI, followed by pneumonia, C. Diff., MRSA, and VRE
- Infection that results from a defective immune system that cannot defend against pathogens normally found in environment.
- Health and immunity of host have been severely weakened by illness, famine, or medical therapy.
Transmission of infections- Chain of infection
C. P. R. P. M. C
- Characteristic of organism
- portal of entry
- Portal of exit
- Mode of Transmission
- Characteristic of host
Characteristic of Organism (pathogen)
- Any class of organisms capable of producing infection
- ie: Bacteria, rickettsiae, viruses, protozoa, fungi, helminths
Portal of entry
- Organism must gain access to host through an entry point that allows organism interaction
- Prevention involves maintaining integrity of protective tissues in host.
- Sites of potential entry: Mucous membranes, GI Tract, GU tract, respiratory tract, broken skin
- place where infectious agent can survive, and possibly multiply until it can invade susceptible host
- Depends on reservoir for survival and reproduction
- Can be in the body, or on items like a catheter or stethoscope.
Portal of exit
- Way to get out of host or reservoir
- infected host must shed organisms to another host or to environment
- Can exit through: GI Tract, GU tract, respiratory tract, skin or mucosal surfaces, blood.
Mode of Transmission
- needed to connect infectious source with its new host.
Mode of transmission types
- Direct contact
Characteristics of host
- previous infection or vaccine may render host immune
- Many infections are prevented by immune system
- Exposed to many organisms daily, but few people are actually infected.
Susceptible or Highest risk hosts
P, M, V, I, S, D
- People with low levels of WBCs
- Very young or Very old
- Immunosuppressive therapy
- Sever trauma or burns
Common agents of infectious disease
P, V, B, R (CEC), F, P
- Rickettsia, Chlamydiae, Ehrlichieae, and coxiella
- Protein particles that lack a genome
- Are infectious and capable of duplication
- Called transmissible neurodegenerative disease
- IE: Mad Cow disease, creudtzfeldt- Jakobs
- Can only live inside cells
- Replication depends totally on ability to infect host cell
- insert RNA or DNA into cell
- Autonomously replicating unicellular organism
- Cytoplasm surrounded by flexible lipid membrane (cytoplasmic membrane)
- Physical appearance of bacterial colony grown on agar plate are distinctive for each species
- Classified as either gram negative or positive.
- Gram + release toxins that damage host cells
- Gram - contain proteins in cell walls that stimulate inflammatory response.
Rikettsia, Chlamydia, ehrlichieae, and coxiella
- combine characteristics of both viral and bacterial agents
- intracellular pathogens like viruses.
- Produce rigid cell wall, reproduce asexually by cell division, and contain RNA and DNA similar to bacteria.
- Few are able to produce disease in humans
- Some are normal microflora
- Can cause serious life threatening opporunistic disease.
- Protozoa (unicellular animals)
- Helminthes (wormlike)
- Arthropods (ticks, mosquitoes, lice)
Diagnostic tests for screening of infectious diseases.
C. S. A. W. E
- Culture and Sensitivity
- Serology (antibody titer)
- antigen detection
- WBC Count and differential
- Erythrocyte Sedimentation rate (ESR)
Culture and Sensitivity (C&S)
- Propagation of microorganism outside of body, usually on artificial growth media, that identifies the organism
- Determines susceptibility of patients infection to antibiotics
Serology (antibody titer)
- Indirect means of identifying infectious agents by measuring serum antibodies in disease host
- negative finding or normal titer indicates absence of antibodies.
-Purified antibodies detect antigens of infectious agents in specimens obtained from disease host.
WBC count and differential
- Counts the number of WBCs found in a micro liter of whole blood.
- Determines infection or inflammation
- Determine needs for more testing
- Monitors response to chemotherapy
Erythrocyte sedimentation rate (ESR)
- Measures the degree of erythrocyte settling during a specific time period
- Frequently early indicator of disease when other chemical or physical signs are normal.
Drug therapy for infection goals
- Complete removal of pathogen from host
- Restoration of normal physiologic function to damaged tissues
Type of drug therapy
- Chemical substance that inhibit or destroy other microorganisms
- Must attack invading organism without seriously impairing host
mechanisms of Antibiotic action
- Interfere with step in bacterial wall synthesis
- Inhibit bacterial protein synthesis
- Interrupt nucleic acid synthesis
- Interfere with normal metabolism
- Viruses Can only live inside cell
- Their replication depends totally on ability to infect a host cell
- Primary target is viral RNA or DNA synthesis
- Destroys or inhibits growth of fungi
- Fungicidal (kills fungi)
- Fungistatic (sops fungal growth)
- Not many options as they are also very toxic to humans
- Agents that reduce fever
- Acetaminophen and aspirin act on hypothalamic heat-regulating center
- Take with food to minimize GI irritation and call MD if fever not relieved by routine doses.
A. F. T. R. P
- Assessment priorities
- Fluid and Electrolytes
- Temperature regulation
- Rest and Activity
- Patient teaching.
Preventative measure and infection control
H. P. I. O. C. C
- Hand washing
- plan ahead
- use isolation precautions
- Observe asepsis as indicated
- Carry out concurrent disinfection of fomites
- control or eliminate reservoirs
Preventative measure and infection control
C. C. V. H. S
- Control dissemination of infectious droplets
- Control dust and maintain environmental cleanliness
- Ventilate patient's room properly
- Help strengthen a host's defenses
- standard precautions
H, G, M, G, L, O
- Hand washing
- Mask, eye protection, face shield
- Occupational health and bloodborne pathogens