infection control Flashcards by Sharmaine Madjid

development of an infection and disease

pathogenesis

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involves the growth and multiplication of microorganisms that cause damage to the host

infection

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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

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an infection caused by a microorganism from the microbiota of the host.

autogenous infection

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an infection that occurs as the result of some medical
treatment or procedure.

iatrogenic infection

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an infection that affects immunocompromised hosts but not the individuals with a normal immune system.

opportunistic infection

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also known as the hospital-acquired infection and type of infection that is acquired at a healthcare facility

nosocomial infection

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the cornerstone of modern infection control programs

hand washing

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4 common types of nosocomial infections

urinary tract infection
lung infection
surgical site infection
blood stream infection

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Predisposing factors to nosocomial infections

a. Wide variety of microbes in the hospital environment

b. Weakened or immune-compromised patients

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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

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signs and symptoms are confined in one area such as infected wounds, boils and abscesses

local infection

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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

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microbes spread throughout the body through the blood or lymph.

systemic infection (generalized infection)

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– 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

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active multiplication of the invading bacteria in the blood.

septicemia

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condition wherein pus-producing organisms repeatedly invade the bloodstream and become localized at different parts of the body.

pyemia

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an initial infection that causes the illness such as colds

primary infection

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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

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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)

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an infection caused by two or more organisms such as wound infection

mixed infection

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type of infection that develops and progresses slowly
such as whooping cough

Acute infection

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an infection which develops slowly with milder but
longer-lasting symptoms such as tuberculosis

chronic infection

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2 routes of infection

direct and indirect

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- 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

1. Gender 2. Genetic factors 3. Climate and weather 4. Nutrition 5. Fatigue/stress 6. Environment 7. Lifestyle 8. Age 9. 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

1. Physical barriers 2. Cleansing mechanisms 3. 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

1. Adherence 2. Proliferation 3. Tissue damage 4. 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