LEC: Infection Flashcards
infection and immunity involves interaction between the ____________ and _____________
between the body of the host and the infecting microorganism
microorgnisms can be classified according to their relationship with the _________ and ___________
environment and their host
``
these are free living microbes that live and thrive on dead or decaying organic matter
saprophytes
the term “saprophytes” come from what greek words
“sapros” = decayed, “phyton” = plant
these organisms typically have little importance to human diseases
saprophytes
organisms that have little relevance in infectious diseases
saprophytes
organisms that are commonly found in soil and water
saprophytes
right now, these organisms are being studied among immunocompromised patients, which makes them an opportunistic pathogens
saprophytes
microorganisms that are also called as “normal or usual flora’”
commensal
the live and thrive within the host but they do not cause harm nor benefit from their host
commensal
these microorganisms are mostly found inside the body
commensal
these microrganisms live in complete harmony with their host
commensal
Pathogen is derived from what greek words
“pathos” = disease
“gen” = produce
there is a wide variety of clinically important pathogens; some of which are what
bacteria, fungi, viruses, and parasites.
it is the ability of the pathogen to cause disease
pathogenicity
the degree or level of their pathogenicity
virulence
it describes how easy a microorganism can cause disease and how fatal the infection would be
virulence
the 2 main types of pathogens
- primary (frank) pathogen
- opportunistic pathogens
these are type of microorganisms that can cause disease to an individual regardless of their immune condition
primary (frank) pathogens
these causes disease to previously health individuals
primary (frank) pathogens
these microorganisms are known to cause infectious diseases even if the immune system is intact
primary (frank) pathogens
they rarely cause disease to healthy individuals
opportunistic pathogens
they are known to only cause disease to individuals with impaired or compromised immune system
opportunistic pathogens
is defined as the bodily invasion of microorganisms which involve replication of the agent within the host.
infection
is defined as the bodily invasion of microorganisms which involve replication of the agent within the host.
infection
In most cases though, __________________ agents result in the damage to the host tissues and organs.
multiplication of the microbial
Initial infection of an organisms in the host Initial infection of an organisms in the host
primary infection
some ________ can be an opportunists, Such happens when the immune defense system of the host is compromised and the normal flora takes over and gets out of control.
normal flora
Subsequent infections by the same organism in the host
Reinfections
When the host has recovered from the primary infection and got infected again by the same agent, it is called _________________.
reinfection
When a new agent sets up an infection in a host whose resistance is lowered by a preexisting infectious disease,
Secondary infection
Apart from the cell and tissue damage caused by a primary infection, it may also exhaust and weaken the host’s immune system. This gives other agents or microorganisms a chance to establish their own infection. This is classified as what type of infection?
Secondary infection
an infection that is confined in one area or part of the body
local infection
give an example of local infection
infected wound
This is in direct contrast with systematic or generalized infection
local infection
an infection where the microbes have spread throughout the body through the blood or lymph
Systematic infection
Cross-infections occurring in hospitals are called
Nosocomial infections
type of infection that is acquired at a healthcare facility and are best controlled through hand washing to avoid spread.
nosocomial infection
Contributing factors to nosocomial infections include
- wide variety of microbes present in hospital environments
- the constant presence of immunocompromised patients
- possible direct transmission from healthcare workers to patients and from patients to other patients.
refers to physician induced infections resulting from investigative, therapeutic or other procedures.
iatrogenic infection
this infection is a result of medical treatment or procedures.
iatrogenic infection
Urinary tract infection due to cathetherization and wound infection following blood collection are prime examples of what type of infection
iatrogenic infection
a type of infection where clinical effects are not apparent
inapparent infection
it is often used as a synonym to inapparent infection.
subclinical infection
this type of infection refer to the proliferation of organisms in a host in which there are no apparent signs or symptoms.
Inapparent or subclinical infections
this type of infection is one in which the typical or characteristic clinical manifestations of the particular infectious disease are not present
atypical infection
Some organisms, following infection, may remain in the tissues in a hidden form proliferating and producing clinical disease when the host resistance is lowered. This is termed _____________.
latent infection
There are cases where an organism is present inside the body of the host but is dormant and inactive where it presents no noticeable disease or illness. what infection
latent infection
Human source infections are transmitted through:
o Airborne transmission
o Direct contact
o Through infected materials (Fomites)
Most common source of infection for human beings is ___________________
human beings themselves.
it is person who harbors the microorganisms without suffering from any ill effect` because of it.
carrier
An individual who has recovered from the infectious disease but continues to harbor large numbers of pathogen.
Convalescent carrier
is an individual who harbors the pathogen but is not ill.
A healthy carrier
is an individual who is incubating the pathogen in large numbers but is not yet ill.
incubatory carrier
Individual that does not have signs or symptoms because the disease is still in its incubation phase but are still capable of spreading the infection.
incubatory carrier
Convalescent, healthy, and incubatory carriers may harbor the pathogen for only a brief period (hours, days, or weeks) and lasts less than six months.
Temporary carriers
They harbor the pathogen for long periods (months, years, or life).
chronic carriers
The term ______________ is applied to a person who acquires the pathogen from a patient
contact carrier
This refers to a carrier who acquires the pathogens from another carrier.
Paradoxical carrier
Many pathogens are capable of causing infections in both human beings and animals. Therefore, animals may act as a source of infection of such organisms. These, animals serve to maintain the parasite in nature and act as reservoir and they are, therefore, called
reservoir hosts
The diseases and infections, which are transmissible to man from animals are called
zoonosis
defined as a disease of animals that is transmitted to humans.
Zoonosis or zoonotic infection
Anthrax, brucellosis, Q fever, leptospirosis, bovine tuberculosis, bubonic plague, Salmonella food poisoning.
bacterial (Zoonotic Diseases)
Rabies, yellow fever, cowpox, monkeypox.
viral (Zoonotic Diseases)
Leishmaniasis, toxoplasmosis, trypanosomiasis, babesiosis.
protozoal (Zoonotic Diseases)
Echinococcosis, taeniasis, trichinellosis.
helminthic (zoonotic diseases)
Microsporum canis, Trichophyton verru- cosum
fungal (zoonotic diseases)
zoonotic infection that is transmitted through bites of rabid animals to hosts
Rabies
disease caused by a spirochete bacteria, often acquired by the exposure of broken skin with the urine of an infected animal.
leptospirosis
As the insects that transmit this infections are called vectors, they are referred to as _____________ or _____________ diseases.
vector-borne or arthropod-borne diseases
Blood-sucking insects, such as mosquitos, ticks, mites, flies, and lice may transmit pathogens to human beings and diseases so caused are called _______________
arthropod-borne diseases.
Besides acting as vectors, some insects may also act as _____________ (for example, ticks in relapsing fever and spotted fever).
reservoir hosts
Insects that transmit infections are called ________
vectors
this type of transmission can be of two types either mechanical (external) or biological (internal).
vector-borne
a type of vector in which the disease agent is transmitted mechanically by the arthropod.
mechanical vector
Those that carry microorganisms through their feet and mouth parts and proceed to infect hosts when they land on food, mucous membranes, or open wounds. what type of vector?
mechanical vector
Prime examples are flies that carry bacteria when they land on infected materials such as feces and proceed to drop this bacteria when they land on human food. what type of vector?
mechanical vector
those in whom the pathogens multiply sufficiently or has undergone a developmental cycle. what type of vector?
biological vector
Aedes aegypti mosquito in yellow fever, Anopheles mosquito in malaria are what type of vector?
biological vector
Those that are used by microbes as part of their life cycle. what type of vector?
biological vector
Microorganisms within __________ vectors undergo change and development until such a time that the vector itself because the source of infection.
biological vector
Prime example is the parasitic infection malaria, caused by plasmodium parasites that develop inside anopheles mosquitoes. what type of vector?
biological vector
Spores of ** and ** remain viable in the soil for several decades and serve as source of infection.
tetanus and gas gangrene
Spores of *** can survive in the soil for long periods and when given access to the body such as through wounds may cause tetanus.
clostridium tetani
Fungi (causing **, **, and ***) and parasites such as roundworms and hookworms also survive in the soil and cause human infection.
causing mycetoma, sporotrichosis, histoplasmosis
*** are also known to be obtained through the soil such as when children proceed to eat without washing their hands after playing with dirt.
Parasitic infections
TRUE OR FALSE: Pathogens in contaminated water can also cause outbreaks of diseases.
true
*** may act as the source of infection either due to contamination with pathogenic microorganisms (Shigella, Salmonella, Vibrio cholerae, poliomyelitis virus, hepatitis virus) or due the presence of aquatic vector (cyclops containing larvae of guinea worm infection)..
Water
causative agent of typhoid fever
Salmonella
causative agent of Cholera
Vibrio cholerae bacteria
bacteria that causes traveller’s diarrhea
E. coli
what enteric pathogens that are known to be transmitted through ingestion of contaminated water?
- Salmonella (causative agent of typhoid fever)
- Vibrio cholera (causative agent of Cholera)
- pathogenic strains of E.coli (causes traveller’s diarrhea)
What enteric pathogens are known to be transmitted through ingestion of contaminated water.
- Salmonella (causative agent of typhoid fever)
- Vibrio cholera (causative agent of Cholera)
- pathogenic strains of E.coli (causes traveller’s diarrhea)
** may act as source of infection of organisms causing food poisoning, gastroenteritis, diarrhea and dysentery.
Contaminated food
Most of the time, such infections affect the gastrointestinal tract leading to ** and **
gastroenteritis and diarrhea
Common way of transmitting infection.
contact
Infection may be acquired by contact, which may be ** or **
direct or indirect.
STD (sexually transmitted diseases), such as syphilis, gonorrhea, lymphogranuloma venereum, lymphogranuloma inguinale, trichomoniasis, herpes simplex type 2,hepatitis B and acquired immunodeficiency syndrome (AIDS) are transmitted via
direct contact
Diseases transmitted by direct contact include
- STD (sexually transmitted diseases)
- syphilis
- gonorrhea
- lymphogranuloma venereum
- lymphogranuloma inguinale
- trichomoniasis
- herpes simplex type 2 - hepatitis B
- acquired immunodeficiency syndrome (AIDS)
This may include venereal disease or sexuallytransmitted infections such as gonorrhoea, syphilis,hiv, aids. (MODES OF TRANSMISSION OF INFECTION)
direct contact
mode of transmission such as when a person coughs and covered his mouth with his hands and proceed to touch another person.
hand-to-hand transmission
*** may be through the agency of fomites, which are inanimate objects, such as clothing, pencils or toys which may be contaminated by a pathogen from one person and act as a vehicle for its transmission to another.
Indirect contact
Is a transmission that involves the source of infection an inanimate object called fomites, and a susceptible host.
indirect contact
Microorganisms from the reservoir can be passed on through the *** and infect a new host.
fomites
Doorknobs, clothing, and everyday objects can be classified as ***.
fomites
mode of transmission that is through inhalation of respiratory droplets is a mechanisms in which respiratory infections are passed.
airborne transmission
Respiratory infections, such as common cold, flu, influenza, measles, mumps, tuberculosis and whooping cough are acquired by inhalation. what mode of transmission
airborne transmission
these are fine particles that are produced when respiratory secretions are aerosolized through sneezing and coughing.
droplet nuclei
generally acquired by the ingestion of food or drink contaminated by pathogens. what type of infection
intestinal infection
Infection transmitted by ingestion may be water borne (cholera), food borne (food poisoning o hand borne (dysentery).
intestinal infection
Ingestion of contaminated food or water may result in (type of infection), therefore careful preparation is necessary to avoid outbreaks of diarrhea and possible food poisoning
gastrointestinal infections
Intestinal infections are generally acquired by the ingestion of food or drink contaminated by pathogens. this belongs to what mode of transmission?
Ingestion
Disease agent may be inoculated directly in to the skin or mucosa, e.g. Rabies virus deposited subcutaneously by dog bite, tetanus spores implanted in deep wounds, and arboviruses injected by insect vectors. This belongs to what mode of transmission?
Inoculation
e.g. Rabies virus deposited subcutaneously by dog bite, tetanus spores implanted in deep wounds, and arboviruses injected by insect vectors. What mode of transmission is mentioned
inoculation
Infection by inoculation may be *** when unsterile syringes and surgical equipment are employed.
iatrogenic
A deep piercing wound is a possible way of contracting tetanus such as when a person steps on a sharp object contaminated with clostridium tetany. Reusing intravenous needles between different individuals also pose a risk. What mode of transmission?
Inoculation
defined as an arthropod or any living carrier (e.g. snail) that transports an infectious agent to a susceptible individual.
vector
Some pathogens are able to cross the placental barrier and reach the fetus in uterus. What mode of transmission?
Vertical Transmission
Mother to child transmission is also possible inside the womb as some pathogen are able to pass through the placenta and reach the developing fetus. What mode of transmission?
vertical transmission
This may have serious complications that may lead to birth defects and death of the child as in the case of rubella. What mode of transmission?
vertical transmission
If meticulous care in asepsis is not taken, infections like ** and ** may sometimes be transmitted during administration of injections, lumber puncture and catheterization.
AIDS and hepatitis B
These are known as iatrogenic or *** infections.
physician-induced infections.
Modern methods of treatment, such as exchange transfusion, dialysis, and heart and transplant surgery have increased the possibilities for ***
iatrogenic infections.
Medical procedure such as blood collection, catheterization, insertion of needles for IV contractions can also transmit or induce infection to an already deceased or immunocompromised patient. What type of infection?
iatrogenic or physician-induced infection
it is the ability of a microbe to produce disease in a susceptible individual
pathogenicity
Relates to the capability of an organism to cause disease to a susceptible host.
pathogenicity
the relative ability of microorganism to cause disease or the degree of pathogenicity.
virulence
The degree or level of pathogenicity of an organism
virulence
It is usually measured based on its infective dose or the number of microorganisms needed to establish infection, the lower the infective dose the more virulent the agent is.
virulence
The severity of the disease produced is also considered, the more severe and fatal the resulting infection the more virulent the microorganism.
virulence
reduction of virulence
attenuation
A process that reduces the infectivity of microorganisms can enter the body of the host
attenuation
The first step of the infectious process is the entry of microorganism into the host by one of several ports: the respiratory tract, gastrointestinal tract, urogenital tract, or through skin that has been cut, punctured, or burned. What determinant of virulence
transmissibility
Refers to how easy a microorganism can enter. the easier the agent is transmitted, the more virulent it can be. What determinant of virulence
transmissibility
Entry to the human body can be through inhalation of respiratory droplets through broken skin, direct contact or ingestion. what determinant of virulence>
transmissibility
The initial event in the pathogenesis is the attachment of the bacteria to body surfaces. what determinant of virulence
adhesion
This attachment is not a chance event but a specific reaction between surface receptors on host cells and adhesive structures (ligands) on the surface of bacteria. what determinant of virulence
adhesion
This attachment is not a chance event but a specific reaction between * on host cells and adhesive structures (* ) on the surface of bacteria.
surface receptors;
ligands
*** may occur as organized structures, such as fimbriae or fibrillae and pilli, or as colonization factors.
adhesions
are usually made of protein and are antigenic in nature.
adhesins
*** with adhesins has been attempted as a method of prophylaxis in some infections.
specific immunization
A microorganism must attach itself to cells and tissues of the host in order to establish infection. This happens when adhesins; the structure that mediate attachment binds to the receptors on the host cells. What determinant of virulence is mentioned?
adhesion
Adhesins in bacteria include the ** and ** . Attachment by bacteria to the host cells increases its colonizing ability and may offer protection against phagocytosis
common pili and fimbriae
As adhesins are protein and antigenic in nature, development of immunity from such may be an effective way of ** **
avoiding infection
this signifies the ability of a pathogen to spread in the host tissues after establishing infection.
invasiveness
** ** pathogens characteristically produce spreading or generalized lesions (e.g. Streptococcal septicemia following wound infection)
Highly invasive
in infection caused by highly invasive pathogen
Streptococcal septicemia following wound infection
** ** pathogens cause more localized lesions (e.g. staphylococcal abscess).
Less invasive pathogens
A process which pathogens penetrate and colonize the tissues. This is an important factor as it determines if an organism is capable of dissemination to distant sites in the body
invasiveness
** organisms can cause generalized infection, while ** organisms stay localized in the initial site or tissue
highly invasive; less invasive
Some bacteria cause disease by producing toxins, of which there are two general types. what determinant of virulence?
toxigenicity
*** are substances that are released by microorganisms that disrupt the normal metabolism of cells resulting to cell and tissue damage
Toxins
are soluble, heat-labile proteins inactivated at 60°–80°C and diffuse readily into the surrounding medium.
exotoxins
a type of toxin that are highly potent in minute amounts and include some of the most poisonous substances known.
exotoxins
Treatment with *** converts exotoxin into toxoids, are thus useful in preparing vaccines.
formaldehyde
Treatment with formaldehyde converts exotoxin into ***, are thus useful in preparing vaccines.
toxoids
toxins that exhibit specific tissue affinity and pharmacological activities.
exotoxins
toxins that are associated with specific diseases and have specific mechanisms of action.
exotoxins
exotoxins are easily inactivated by **, **, and other chemicals to form immunogenic toxoids.
formaldehyde, iodine,
*** are generally formed by gram- positive bacteria but may also be produced by some gramnegative organisms such as Shiga’s dysentery bacillus, cholera vibrio and enterotoxigenic E. coli.
exotoxins
toxins that can be produced by either gram-positive or gramnegative bacteria which are released into the extracellular environment
exotoxins
a type of toxin that has specific biologic activity against the host cells. some causes paralysis, diarrhea, or tissue damage.
exotoxins
Such toxins are protein in composition and are heat sensitive which can be inactivated by increased temperature and can be detoxified with the use of formaldehyde
exotoxins
These toxins are heat-stable, lipopolysaccharide (LPS) components of the outer membranes of gram negative.
endotoxins
Their toxicity depends upon the component (lipid A).
endotoxins
toxins that are released into the host’s circulation following bacterial cell lysis.
endotoxins
They are toxic only at high doses.
endotoxins
They cannot be toxoided.
endotoxins
toxins that are poor antigens and weakly immunogenic.
endotoxins
They do not exhibit specific pharmacological activities.
endotoxins
Intravenous injections of large doses of endotoxin and massive gram-negative septicemias causes ***
endotoxic shock
*** is marked by fever, leukopenia, thrombocytopenia, significant fall in blood pressure, circulatory collapse and bloody diarrhea leading to death
endotoxic shock
toxins that are substances found in the outer membrane and are exclusive only to gram-negative bacteria.
endotoxins
The toxic activity of endotoxins come from the *** a component of the cell wall.
lipid
Endotoxins are released only after ** **
cell lysis
The toxicity of endotoxins consist of changes in bodily function such as ** ** ***
low blood pressure.
Endotoxins also causes intravascular coagulation of blood that may result in ***.
bleeding
Fever and decreased circulating white blood cells are also observed as effects of what toxins
endotoxins
exotoxins: proteins,
endotoxins: ***
lipopolysaccharide on the outer membrane, Lipid A portion is toxic
exotoxins: ***
endotoxins: heat-stable
heat-labile, inactivated at 60-80 degree Celsius
The human body contains circulating neutrophils and macrophages that ingest foreign materials in a process called *** .
phagocytosis
However microbes evolved to produce structures that *** phagocytosis.
inhibit
name some bacteria that can produce a slippery mucoid capsule that prevents the phagocyte from effectively contacting the bacterium.
- Streptococcus pneumoniae
- Neisseria meningitidis
- Haemophilus influenzae
these are polysaccharide coating that mask the surface structure of bacteria that is also necessary for recognition for phagocytes
capsules
these prevents binding of the host antibodies to the bacterial cell
capsules
other bacteria evade phagocytosis by producing specialized surface proteins such as *** on Streptococcus pyogenes
Streptococcal M protein
