Pathogenesis Of Infection Flashcards
“Genesis” means?
Origin
It is the invasion of the body by pathogenic microorganisms that reproduce and multiply, causing disease by local cellular injury, secretion of toxin, or antigen-antibody reaction in the host
Infection
4 types of infection
- Autogenous
- Iatrogenic
- Opportunistic
- Nosocomial
Cause by microorganism from the microbiota of the individual
Autogenous infection
An infection that occurs as the result of medical treatment or medical procedures
Iatrogenic infection
An infection in immunocompromised hosts that do not cause disease in individuals with a normal immune system. It may due to overuse of antibiotics, immunosuppressive drugs and chemotherapeutic agents
Opportunistic infection
Known as the hospital acquired infection.
Nosocomial infection
Cornerstone of modern infection control programs
Hand washing
4 common Nosocomial Imfections
- UTI
- Lung Infection (Pneumonia)
- Surgical site infection
- Blood stream infection
Predisposing factors to Nosocomial Infection
- Wide variety of microbes in hospital environment
2 weakened or immunocompromised patients - Chain of transmission (direct or indirect)
Examples of Chain transmission
- From health workers to patient
- From patient to patient
- Fomites (catheters, needles,dressings, beds, wheelchairs)
- Airborne transmission
- Vector-borne transmission
Types of infection according to distribution in the host
Local infection
Focal infection
Systemic (Generalized infection)
It means signs and symptoms are confined to one area. Such as infected wound, boils, abscess, and acne.
Local infection
It starts as a local infection and spread to other parts of the body
Focal infection
Microbes are spread throughout the body by blood or lymph ( general invasion )
Systemic (Generalized infection)
It is the presence of bacteria in the blood
Bacteremia
It is the active multiplication of bacteria in the blood
Septicemia
It is a condition wherein pus-producing organisms repeatedly invade the blood stream and localized at different parts of the body
Pyemia
It is the presence of toxins in the blood
Toxemia
Is an initial infection causing the illness
Primary infection
It is caused by opportunistic pathogen after primary infection has weakened host immune system
Secondary infection
Is clinically silent inside the body without any noticeable illness in the host before suddenly causing severe and acute infectiom
Latent infection
Other name for latent infection
Silent phase
It is caused by two or more organisms
Mixed infections
Is a type of infection that develops and progress slowly
Acute infection
An infection which develops slowly with milder but longer-lasting symptoms
Chronic infection
Routes of infection
Direct transmission
Indirect transmission
Examples of direct transmission
Congenital contact
Sexual contact
Hand-to-hand transmission
Infectious respiratory secretion or droplets
Examples of indirect transmission
Fomites
Water
Arthropod vectors
It is a specific illness or disorder characterized by recognizable set of signs and symptoms attributable to hereditary, infection, diet or environment
Disease
Classification of infectious diseases
Communicable
Contagious
Non-communicable
It is spread from one host to another, directly or indirectly such as TB, herpes, AIDS, chicken pox mumps, polio and hepatitis
Communicable disease
It is spread from one person to another such as chicken pox and measles
Contagious disease
It is not spread from host to another. Caused by microbes that live outside the body or by opportunistic pathogens that live inside the body
Non-communicable disease
Classification of disease as to occurence
Sporadic disease
Endemic disease
Epidemic disease
Pandemic disease
It occurs occasionally
Sporadic disease
Constantly present in a particular location or population
Endemic disease
Many people acquire the disease in a particular location or population
Epidemic disease
An epidemic that spans the world
Pandemic disease
These are objective changes that can be measured
Signs
These are subjective feelings not obvious to a person
Symptoms
Is a group of signs and symptoms that are associated with a disease
Syndrome
Phases of infectious diseases
- Incubation period
- Prodromal period
- Clinical/illness period
- Decline period
- Convalescent period/period of recovery
Time between the exposure to a pathogenic organism and the onset of symptoms
Incubation period
Is the appearance of the signs and symptoms
Prodromal period
Is the peak of characteristic signs and symptoms of an infection or a disease
Clinical/illness period
Is the period wherein the signs and symptoms begin to subside as the host condition improves
Decline period
Is the full recovery of the surviving host
Convalescent period/ period of recovery
Predisposing factors (disease):
Age Genetic factors Climate and weather Nutrition Fatigue/stress Environment Lifestyle Age Occupation
Microorganisms that cause infection and/or disease
Pathogens
Pertains to the ability of a pathogenic agent to produce a disease in a susceptible individual
Pathogenicity
2 general classes of Pathogenic Microorganisms
True Pathogens
Opportunistic Pathogens
They ate able to invade the tissues of healthy individuals through some inherent ability (power) of their own
True pathogens
Organisms that normally do not cause disease in their natural habitat in a healthy person— they may cause disease if the host is weakened or if they enter a different part of the body
Opportunistic pathogens
Organism that causes meningitis
Neisseria meningitidis
True or False: E. Coli can cause UTI
True
Is the association of two organisms living together
Symbiosis
Is a symbiotic relationship where both the host and organism benefit from one another
Mutualism
Is a relationship where the organism benefits, but there is mo beneficial or harmful effect to the host
Commensalism
Is a relationship where the organism benefits at the expense of the host
Parasitism
Is a key component in bacterial pathogenesis, and is complex interaction between host, indwelling device and bacteria
Biofilm production
Power of the microorganisms to produce disease. It is the degree of pathogenicity.
Virulence
It pertains to a very pathogenic microorganism or rapidly progressive condition.
Virulent
Factors influencing microbial virulence
Toxic factors
Enzymatic factors
Cellular factors
Poisonous substances produced by pathogenic microorganisms
Toxins
Ability to produce toxic substances
Toxigenicity
These are produced by bacteria such as coagulase, collagenase, and hemolysin
Enzymatic factors
True or False: Capsule resists phagocytosis
True
Host resistant factors
Physical barriers Cleansing mechanism Antimicrobial substances Indigenous/normal microbial flora Phagocytosis Inflammation Immune response
True or False: The skin serves as the physical and chemical barrier to microorganisms
True
Give one example of physical barrier
Stricture at the urethral opening
Flushing action of urination
Thick mucus plug in the cervical opening
A cleansing mechanism that contributes to the removal of potentially infective agents
Cough-sneeze reflex
Examples of cleansing mechanism
Sweeping of particles by the ciliary epith
Flushing of tears and urine
Examples of antimicrobial substances
Lysozyme
Bile salts
A antimicrobial substance that destroy bacterial cell wall
Lysozymes
A antimicrobial substance that disrupt bacterial membranes
Bile salts
These are microorganisms that are commonly found on or in our body sites of healthy persons. They compete with pathogens for nutrients and space
Indigenous/ normal microbial flora
Inhabit and multiply; colonize an area for months or years
Resident flora
Inhabit but do not multiply; colonize an area temporarily
Transient flora
Microorganisms found in the mouth and oral cavity
Viridans streptococci
Microorganisms found in the upper respiratory tract
Viridans streptococci
S. Epidermidis
diptheroids
Microorganisms found in the nasopharynx
S. aureus
S. epidemidis
N. meningitidis
Microorganisms found in the colon
E. coli
Bacteriodes
Lactobacillus
Microorganisms found in the urethra
Diptheroids
S. epidermidis
Alpha and nonhemolytic streptococci
Process by which certain cells engulf and dispose off microorganisms and cell debris
Phagocytosis
These cells ingest and destroy bacteria and other foreign particles
Phagocytes ( polymorphonuclesr leukocytes and macrophages )
Cells ingest bacteria by a process known as?
Endocytosis
Plays an important role as a reinforcement mechanism against microbial survival and proliferation in tissues and organs
Inflammation
Signs of inflammation
Swelling
Redness
Heat
Pain
Components of inflammation
Phagocytes
Complement system
Coagulation system
Cytokines
Hallmark of inflammatiom
Accumulation of phagocytic cells
Provides the human host with the ability to mount a specific protective response to the presence of microorganism
Immune response
The normal immune system clears bacteria from the blood within how many minutes
30-45 minutes
4 types of immune response
Innate/ natural immunity
Adaptive/ specific immunity
Humoral immune response (antibodies)
Cell-mediated immune response
Produced by B cells in response to presence of foreign molecules
Humoral immune response
Produced by T cells
Cell-mediated immune response
5 Immunoglobulin
IgA IgG IgE IgD IgM
Immunoglobulin seen in secretion
IgA
Biggest immunoglobulin, appears 1st in the 1st exposure
IgM
It is the source or cause of an illness or abnormal condition
Pathogenesis
2 arms of specific immunity
Humoral (antibody-mediated) immunity
Cellular (cell-mediated) immunity
It is based on the action of soluble proteins called antibodies that occur in the body fluids and on the plasma membrane of B lymphocytes
Humoral (antibody-mediated) immunity
Is based on the action of specific kinds of T lymphocytes that directly attack cells infected with viruses or parasites, cancer cells or transplanted cells
Cellular (cell-mediated) immunity
Is the protection of susceptible humans and domestic animals from communicable diseases by administration of vaccines
Active immunization
It is administered to individuals exposed to certain pathogens that cause diseases such as botulism, diptheria, hepatitis, measles, rabies and tetanus
Passive immunization
Is a non- specific response which activates chemotaxis, the process by which phagocytes are directed to the site of proliferation and engulf invading organism
Natural (innate) immunity
Is the specific response of the host to an invading organism
Acquired active immunity
These are antibodies attached to the surface of microorganisms and render pathogens susceptible to phagocytosis
Opsonizing antibodies
These are antibodies attached to the surface of microorganisms and block surface receptors
Neutralizing antibodies
These are antibodies attached to the surface of pathogens and destroy antibodies by lysis
Complement-fixing antibodies
Is a major genetically determined change in the antigenic character of a pathogen which may result to not being recognized by the host’s immune system
Antigenic shift
Is a minor antigenic change as a result of mutation in pathogen strains, and facilities the pathogen avoids host immune responses
Antigenic drift
Is the ability of B lymphocytes to recall pathogens during primary exposure, thus second exposure elicits higher antibody response
Anamnestic response
Infectious agent factors
Adherence Proliferation Tissue damage Production of toxins Invasion Dissemination
What are the main adhesins in the bacteria
Pili (fimbriae)
Surface polysaccharides
Inhibits proliferation
Secretory antibody
Lactoferrin
Lysozyme
Is a result of either preformed toxin or disruption of the normal functioning of the cells
Tissue damage
2 types of toxins
Exotoxin
Endotoxin
These are among the most lethal substances known; specific and more limited; present in Gram-positive bacteria
Exotoxin
Toxin gene is commonly encoded by
Phages
Plasmids
Transposons
These are composed of the lipopolysaccharide portion of the cell wall; present in Gram-negative bacteria
Endotoxin
True or False: Endotoxin stimulates the fever center in the hypothalamus
True
In the production of fever, 5 substances are important:
Endotoxin Peptidoglycan Cytokines Interlukin-1 and tissue necrosis factor Acute phase reactants
The process of penetrating and growing inside in tissues
Invasion
The spread of organisms to distant sites
Dissemination
Respiratory spread of infectious disease is common. Secretion are aerolized by coughing, sneezing and talking
Airborne transmission
Small residues from the evaporation fluid fro, larger droplets and are light enough to remain airborne for long periods
Droplet nuclei
True or False: Infections of the lower respiratory tract are more common but less serious than those of the upper respiratory tract
False
Less, more
Infections occur via the fecal-oral route
Transmission by food and water
True or False: gastric enzymes and juices in the stomach act to prevent survival of most organisms
True
It refers to passage of organisms by salivary, skim, and genital contact
Close contact
Infection by the normal flora of the mouth
Bites
Where infectious agent multiply, then feeds off human host and transmits the microorganism
Arthropods
It depends on the contact with animals or animal by-product
Zoonoses
Study of occurrence, distribution, and causes of disease and injury
Epidemiology
Person or animal who harbors and spreads a microorganism that causes disease but who does not become ill
Carrier
It harbors the microorganism temporarily for a few days or weeks
Casual/acute/ transient carrier
It remains infected for relatively long time, sometimes throughout life
Chronic carrier
Is an individual who has recovered from infection but continues to harbor large numbers of the pathogen
Convalescent carrier
Is an individual who has an overt clinical case of the disease
Active carrier
When an organisms or disease is constantly present in a population
Endemic
When a disease affects significantly large number of people at the same time in a geographic area
Epidemic
Is an epidemic over a large are affecting tens of millions of people
Pandemic
Is the number of times a new event occurs in a given period
Incidence rate
Time between exposure to a pathogen and the onset of symptoms
Incubation period
Is the number of cases of a disease in a specified population during a defined time interval
Morbidity rate
Is the number of deaths due to a disease in a population
Mortality rate
Source of an infection, may be a person, animal pr something in the environment
Reservoir
