infection control Flashcards
development of an infection and disease
pathogenesis
involves the growth and multiplication of microorganisms that cause damage to the host
infection
Bodily invasion of pathogenic microorganisms that reproduce, multiply, and then
cause diseases through local cellular injury, toxin secretion, or antigen-antibody
reaction in the host.
infection
an infection caused by a microorganism from the microbiota of the host.
autogenous infection
an infection that occurs as the result of some medical
treatment or procedure.
iatrogenic infection
an infection that affects immunocompromised hosts but not the individuals with a normal immune system.
opportunistic infection
also known as the hospital-acquired infection and type of infection that is acquired at a healthcare facility
nosocomial infection
the cornerstone of modern infection control programs
hand washing
4 common types of nosocomial infections
urinary tract infection
lung infection
surgical site infection
blood stream infection
Predisposing factors to nosocomial infections
a. Wide variety of microbes in the hospital environment
b. Weakened or immune-compromised patients
the chain of transmission
i. From health workers to patients
ii. From patient to patients
iii. Use of fomites
iv. Airborne transmission
v. Vector-borne transmission
signs and symptoms are confined in one area such as infected wounds, boils and abscesses
local infection
starts as a local infection before spreading to the other parts of the body such as tooth infection, tonsillitis, appendicitis, and wound infections caused
by Clostridium tetani.
focal infection
microbes spread throughout the body through the blood or lymph.
systemic infection (generalized infection)
– presence of bacteria in the blood.
- organisms invade the bloodstream without active multiplication
- Highest concentration of bacteria in the blood occurs before the fever spikes.
bacteremia
active multiplication of the invading bacteria in the blood.
septicemia
condition wherein pus-producing organisms repeatedly invade the bloodstream and become localized at different parts of the body.
pyemia
an initial infection that causes the illness such as colds
primary infection
an infection caused by opportunistic pathogens after the primary infection has weakened the host’s immune system such as pneumonia and bronchitis that may develop from a common cold.
secondary infection
clinically silent inside the body and causes no
noticeable illnesses in the host. Then severe and acute infection manifests such as asymptomatic type polio infection
Latent infection (Silent phase)
an infection caused by two or more organisms such as wound infection
mixed infection
type of infection that develops and progresses slowly
such as whooping cough
Acute infection
an infection which develops slowly with milder but
longer-lasting symptoms such as tuberculosis
chronic infection
2 routes of infection
direct and indirect
- Congenital contact – Strept.agalactiae, Neisseria gonorrhoeae and Treponema
pallidum - Sexual contact – N.gonnorrhoeae and T.pallidum
- Infectious respiratory secretions or droplets – Strept.pyogenes and N.meningitidis
- Hand-to-hand transmission – Rhinovirus
direct transmission
transmission through fomites, water and arthropod vectors
indirect transmission
A specific illness or disorder that is characterized by a recognizable signs and symptoms which are attributable to heredity, infection, and environment.
disease
It results when the infection produces notable changes in the human physiology, specifically those that cause damage to the body’s organ system
disease
infectious disease classification
communicable or contagious and non-communicable disease
spreads from one host to another, either
directly or indirectly. such as the tuberculosis, herpes, flu, and chickenpox
communicable or contagious disease
does not spread from one host to another and is caused by external microbes or by opportunistic pathogens living in the body. Examples are tetanus and botulism
non-communicable disease
occurence of disease classification
sporadic
endemic
epidemic
pandemic
occurs occasionally
sporadic disease
constantly present in a particular location or population.
endemic disease
disease that affects a large number of people in a population within a short period of time.
epidemic disease
disease that affects populations across large regions around the world.
pandemic disease
infectious disease effects
signs
symptoms
syndrome
these are objective changes that can be measured.
- Examples are fever, redness, swelling, and paralysis
signs
are subjective indications of the disease in a person
- Examples are pain and malaise
symptoms
is a group of signs and symptoms that are associated with a disease.
- Example is AIDS
syndrome
phases of infectious diseases
incubation period
prodromal period
clinical or illness period
decline period
convalescence or period of recovery
the time between the exposure to a pathogenic organism and the onset of symptoms.
incubation period
the appearance of the signs and symptoms.
prodromal period
peak of characteristic signs and symptoms of an
infection or a disease.
clinical or illness period
period in which the signs and symptoms begin to subside as
the host’s condition improves.
decline period
period in which the surviving host is
recuperating towards full recovery.
Convalescence or the period of recovery
predisposing factors of diseases
- Gender
- Genetic factors
- Climate and weather
- Nutrition
- Fatigue/stress
- Environment
- Lifestyle
- Age
- Occupation
these organisms are able to invade the tissues of healthy
individuals through some inherent ability causing various diseases. - normally
found outside the host.
true pathogen
normally do not cause diseases in their natural habitat in healthy person and they cause diseases if the host is immunocompromised or if they enter a different part of the body.
- Examples are Neisseria meningitidis and Escherichia coli.
opportunistic pathogens
association of two organisms living in close proximity.
symbiosis
symbiotic relationship in which both organisms benefit from each
other.
mutualism
a relationship in which one organism benefits while there is no
beneficial or harmful effect to the other.
commensalism
a relationship in which one organism (parasite) benefits at the
expense of its host.
parasitism
a complex interaction between the host, indwelling device,
and bacteria and is a key component in bacterial pathogenesis.
biofilm production
pertains to the ability of a pathogenic agent to produce a disease in
a susceptible individual.
pathogenecity
Ability of the microorganisms to cause diseases.
- degree of pathogenicity
virulence
FACTORS INFLUENCING MICROBIAL VIRULENCE
Toxic factors
Enzymatic factors
Cellular structure
host resistance factors
- Physical barriers
- Cleansing mechanisms
- Antimicrobial substance
4.Indigenous/Normal microbial flora or microbiota
temporarily inhabit, multiply in, and colonize an area for months or years
resident microbiota
inhabit ( but do not multiply) and colonize an area until they are eliminated by either the host’s inherent immune defense or competition with
the resident microbiota.
transient microbiota
microbiota of skin
staphylococcus, propionobacteria and corynebacterium (diphtheroids)
microbiota of mouth and oral cavity
Streptococci viridans
microbiota of upper respiratory tract
Streptococci viridans, diphtheroids and
Staph.epidermidis
microbiota of nasopharynx
– Staph.aureus, Staph.epi, and Neisseria miningitidis
microbiota of e. colon
E. coli, bacteroides, and lactobacilli
microbiota of urethra
diphtheroids, Staph.epidermidis and alpha – and non-haemolytic Streptococci.
- provides the human host with the ability to create a specific protective response
against microorganisms. - “memorizes” all of the encountered microorganisms
immune response
normal immune system removes the bacteria from the blood within how many minutes
30 to 45
- host’s immune response may be reduced or altered due to
immunocompressive
drugs, chemotherapy, or radiation
2 types of specific immunity
humoral/anti-body mediated and cellular/cell-mediated
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
based on the action of specific kinds of
T-lymphocytes that directly attack the cells that are infected with viruses, parasites,
cancer cells, or transplanted cells.
Cellular (cell-mediated) immunity
the protection of susceptible humans and domestic animals from
communicable diseases through the administration of vaccines.
active immunization
specific response of the host to an invading organism.
acquired active immunity
ability of the B-lymphocytes to recall pathogens during the
primary encounter leading to a higher antibody response on the second encounterability of the B-lymphocytes to recall pathogens during the
primary encounter leading to a higher antibody response on the second encounter
anamnestic immunity
a major genetically determined change in the antigenic property of an
organism in which it becomes unrecognizable by the host’s immune system.
antigenic shift
a minor antigenic change as a result of mutation in the organism
strains.
- facilitates the pathogen in avoiding host-immune responses
antigenic drift
these are antibodies that are attached to the
surface of pathogens and which kill the bacteria by lysis.
Complement-fixing antibodies
non-specific response that activates chemotaxis, or
the process which phagocytes
natural (innate) immunity
transient type immunization that is administered to
individuals without fully activating the person’s immune system to create the
corresponding antibodies to diseases.
passive immunization
these are attached to the surface of microorganisms and which render pathogens susceptible phagocytosis.
opsonizing antibodies
infectious agent factors
- Adherence
- Proliferation
- Tissue damage
- production of toxins
2 types of toxins
exotoxin and endotoxins
known to be one of the most lethal substances. Mostly present in Gram
positive and Gram negative bacteria
- do not require bacterial death to be released into circulation.
-do not produce fever to the host
Infectious Agent Factors
- they are either secreted or excreted by living miroorganisms.
-some examples are the cytotoxins , neurotoxins, and enterotoxins.
- some bacteria that produces this kind of toxins are Clostridium botulinum,
C.diphtheria, Staph.aureus and Strept.pyogenes.
exotoxin
composed of the LPS of the cell wall
- present only in Gram negative bacteria
- stimulates the fever center in the hypothalamus
- realeased when bacteria dies and cell wall undergo lysis
- toxicity is due to the lipid A portion of the LPS
endotoxin
process of penetrating and growing in tissues.
invasion
it is the spread of microorganisms to distant body sites.
dissemination
-Respiratory spread of infectious diseases is common
- Secretions are aerolized by coughing, sneezing, and talking
- Tuberculosis, brucellosis, tularemia and plague maybe acquired through inhalation
airborne transmission
infection occur via fecal- oral route
- Gastric enzymes and juices in the stomach prevent the survival of most organisms.
- Salmonella, Campylobacter, E. coli O157:H7
Transmission by food and water
refers to the passage of organism through salivary, skin, and
genital contact.
close contact
cause infection through the normal oral microbiota
cuts and bites
infection multiply within the arthropod which transmits the
microorganisms while feeding off a human host
arthropods
these animal diseases that depends on the contact with animals or
animal by-product for transmission
zoonoses
study of occurrence, distribution, and cause of disease or injury
epidemiology
person or animal that harbors and spreads a microbes that causes a
disease but does not become ill himself.
carrier
harbors the microorganisms temporarily for a few days or
weeks
casual/acute/transient carrier
remains infected for a relatively long time sometimes
throughout its entire life
chronic carrier
an individual who has recovered from infection but
continues to harbour large numbers of the pathogen.
Convalescent carrier
an individual who has an overt clinical case of the disease
active carrier
the organism or disease are indigenous to or
constantly present in a geographic area or population
Likelihood of becoming endemic
affects a significantly large number of people
in a short period of time.
Likelihood of becoming epidemic
affects huge population across the regions like
several countries or a continent
likelihood of becoming pandemic
number of times a new event occurs in a given period
incidence rate
time between the exposure to a pathogen and the onset of
symptoms
incubation period
number of cases of a disease in a specified population during a
defined time interval.
morbidity rate
number of deaths due to a disease in a population
mortality rate
– source of an infection, which may be a person, animal or any object
from the environment.
reservoir
