Thẻ ghi nhớ: 2003MSC EOT MHD Stream Chapters

The upper respiratory tract

is composed of the nose, sinus cavities, pharynx, and larynx.

Microbial colonization is usually limited to the upper respiratory tract

The lower respiratory tract

is composed of the trachea, bronchi, bronchioles, and alveoli.

Defenses of the Airway Epithelium

•Mucociliary clearance traps microbes and particulates larger than 2 µm in a layer of mucus.

•Ciliated epithelial cells move mucus to the pharynx where it is swallowed and sent to the stomach.

What is colonization?

Exposure to disease agents trying to establish a population.

What is infection?

Multiplication of a microbe in a host.

What can happen if the host loses the competition with the microbe?

Disease, tissue or organ damage.

What is the microbiome?

Population of microbes in the body without causing disease.

What is mutualism?

Both host and microbe benefit.

What is commensalism?

Microbe benefits, host is unaffected.

What can antibiotics do to the gut microbiota?

Injure the gut microbiota.

What are superinfections?

Opportunistic pathogens causing new infections on top of preexisting ones.

How can probiotics help after taking antibiotics?

Restore microbiota.

How does the human body maintain symbiosis with its microbiome?

Through mutualism and commensalism.

How does the human microbiome begin at birth?

Colonization from birth, feeding, and environmental contacts.

How many microbial cells does the body contain compared to human cells by adulthood?

10 times more microbial cells.

What happens in parasitism?

Pathogens cause damage and disease in the host.

What is pathogenicity?

Ability to cause disease in a host.

What is virulence?

Degree of pathogenicity.

What are virulence factors?

Structural and chemical factors that contribute to the level of virulence.

What does it mean for an organism to be avirulent?

Lacking virulence factors that can cause infection and disease.

How is an infectious disease diagnosed?

Through signs, symptoms, health history, and physical exam.

What are signs of a disease?

Detectable evidence of a disease, such as abnormal blood pressure or presence of bacterial cells in the blood.

What are symptoms of a disease?

Changes in body function that the patient can feel.

What are syndromes?

Specific collections of signs and symptoms characteristic of a disease.

What is the portal of entry?

The route through which an exogenous pathogen enters the body.

What are the different portals of entry?

Skin, respiratory, GI tract, reproductive/urinary, parenteral.

What is the infectious dose?

The minimal number of microbes needed to cause signs and symptoms of infection.

What are primary infections?

Infections that occur in otherwise healthy bodies.

What are secondary infections?

Infections that occur in a body weakened by primary infections.

What are local diseases?

Diseases that are restricted to a single area.

What are systemic diseases?

Diseases that disseminate to organs and systems.

How do pathogens often spread in systemic diseases?

Through the blood.

What are the routes of entry for pathogens?

Skin, respiratory, GI tract, reproductive/urinary, parenteral.

What is the route of entry for exogenous pathogens?

Through the portal of entry.

What is the route of entry for endogenous pathogens?

Through the normal microbiota.

What is the difference between signs and symptoms?

Signs are detectable evidence, symptoms are changes in body function.

What is bacteremia?

Transient bacteria in the blood.

What is septicemia?

Blood poisoning; large numbers of bacteria.

What is sepsis?

Inflammatory condition resulting from septicemia.

What is fungemia?

Fungi spreading in the blood.

What is viremia?

Viruses spreading through the blood.

What is parasitemia?

Protists and multicellular worms spreading through the blood.

What determines the infection locations of pathogens?

Pathogen's tissue preferences.

What determines pathogen persistence in the host?

Structural virulence factors.

What is the role of encapsulation in pathogens?

Makes them hard to phagocytize.

How do pili/surface proteins on pathogens contribute to infection?

Allow them to stick to specific receptor sites on target cells.

What is the significance of biofilm formation in pathogens?

Allows them to adhere to cells.

What do enzymes do to help pathogens resist body defenses?

Help them form blood clots or dissolve fibrin clots.

What is the role of coagulase in staphylococci?

Forms a blood clot that protects them from phagocytosis.

What is the role of streptokinase in some pathogens?

Dissolves fibrin clots and allows dissemination of the bacteria.

What is the role of hyaluronidase in pathogens?

Enhances pathogen penetration through tissues by digesting hyaluronic acid.

What is the significance of toxigenicity in pathogens?

Ability to produce toxins that cause damage or dysfunction in host cells and tissues.

What is toxemia?

Presence of toxins in the blood.

What are exotoxins?

Proteins produced and secreted by bacteria.

What are cytotoxins?

Toxins that kill cells.

What are neurotoxins?

Toxins that act on the nervous system.

What do enterotoxins act on?

The gastrointestinal tract.

What do antitoxins do?

Neutralize toxins.

What are toxoids?

Toxins with destroyed toxicity but still elicit immune response.

What are endotoxins?

Toxins released from disintegrated gram-negative cells.

What can endotoxins cause?

Blood coagulation and fever.

What can occur with antibiotic treatment of diseases caused by gram-negative bacilli?

Endotoxin shock.

What is a dead-end host?

An infected host that cannot transmit the pathogen to another host.

What are incidental infections?

Infections of dead-end hosts.

What are sequelae?

Aftereffects of infection.

What is the incubation period?

Time between microbe entry and symptom appearance.

What is the prodromal phase?

Time of mild signs or symptoms.

What is the acute period?

Time of intense and specific signs and symptoms.

What is the period of decline?

Time when signs and symptoms subside.

What happens during convalescence?

Body systems return to normal.

What are acute diseases?

Diseases that develop rapidly, cause severe symptoms, and fade quickly.

What are chronic diseases?

Diseases that linger for long periods and are slower to develop and recede.

What are communicable diseases?

Diseases that are contagious and transmittable among hosts.

Give an example of a communicable disease.

Tuberculosis.

What are noncommunicable diseases?

Diseases that are not transmitted to another host.

What is epidemiology?

The foundation of public health.

Give an example of a noncommunicable disease.

Tetanus.

What are reservoirs?

Places in the environment where a pathogen can survive and multiply.

What are the three types of reservoirs?

Nonhuman animal, human, and nonliving.

What are zoonoses?

Diseases spread from animals to humans.

What is a vector?

An organism that transmits a pathogen from a reservoir to a host.

What are carriers?

Individuals who have recovered from a disease but continue to shed the disease agents.

What are the two major modes of infectious disease transmission?

Contact transmission and airborne transmission.

What is direct contact transmission?

Close or personal contact with an infected person.

What is horizontal transmission?

Transmission through person-to-person contact, contact between a person and an infected animal, or sexual intercourse.

What is vertical transmission?

Transmission from mother to fetus or mother to newborn.

What are indirect contact methods of transmission?

Involving nonliving objects, vehicles, and vectors.

What are fomites?

Inanimate objects on which the infectious disease agent lingers.

What is vehicle transmission?

Transmission through the fecal-oral route and contact with contaminated food or water.

What are vectors?

Living organisms carrying disease.

What is mechanical transmission?

Passive transport of pathogens, such as on the feet of flies.

What is biological transmission?

Pathogen multiplies in the vector before being spread.

What is airborne transmission?

Spread of infectious diseases through small particles suspended in air.

How are respiratory droplets spread?

Violently expelled over short distances.

What are droplet nuclei?

Small particles that can remain suspended in the air for indefinite periods.

What is an endemic disease?

A disease that is habitually present at a low level in a specific geographic area.

What is an epidemic disease?

A disease that occurs in a region in excess of what is normally found in that population.

What is an outbreak?

A more contained epidemic.

What is a pandemic?

A worldwide epidemic.

What are healthcare-associated infections (HAIs)?

Infections that occur as a result of receiving treatment for another condition.