micro exam 3

What is a holobiont?

A living system that includes an organism and the organisms living in and on it.

What is the contact, infection, and disease continuum?

Contact with microbes can lead to infection, and infection can lead to disease.

What is colonization?

The establishment of microorganisms in or on a host.

What is infection?

Pathogenic microorganisms penetrate host defenses, enter tissues, and multiply.

Can infection occur without disease?

Yes. Infection is the colonization of an organism by a microorganism, with or without disease.

What is disease?

A pathologic state that results when infection damages or disrupts tissues and organs.

What is an infectious disease?

The disruption of a tissue or organ caused by microbes or their products.

How do colonization, infection, and disease differ?

Colonization is establishing themselves in or on a host; infection involves entering tissues and multiplying; disease occurs when tissues or organs are damaged or disrupted.

What is normal biota?

Microorganisms normally present in and on the body.

What is another name for normal biota?

Normal flora or resident biota.

Where can normal microbiota be found externally?	On the skin and eyes.

On the skin and eyes.

Where can normal microbiota be found internally?

In the nose, mouth, intestinal tract, vagina, and urethra.

Where is most of the body's internal microbiota found?

In the intestinal tract.

What is microbial antagonism?

The ability of normal microbiota to exclude potential pathogens.

• they are good for us; normal flora will kick out pathogens on the skin

what is the impact of the normal flora

It excludes potential pathogens, provides some nutrition, can improve host nutrition, stimulates the immune system, and can also have potential negative impacts

What is the difference between resident and transient microbes?

Resident microbes normally live at a body site, and each site has particular populations; transient microbes do not normally reside there and are just passing through.

Do transient microbes always cause disease?

No. Most are harmless, although some are pathogens.

How can resident microbial populations change?

Each body site has particular populations, and these populations change over time.

What is an opportunistic pathogen?

A microbe that causes disease when conditions allow it, such as when host defenses are weakened.

When can opportunists cause disease?

In immunocompromised individuals.

• A person whose immune system is weakened and cannot fight infections as well as normal.

What conditions can contribute to opportunistic infections?

Breakdown in immunity, certain medical treatments, and implantation of devices.

What is an immunocompromised host?

A host whose immune defenses are weakened.

What is an endogenous infection?

An infection caused by biota already in the body.

How can normal biota cause an endogenous infection?

When normal biota is introduced to a site that was previously sterile.

What is an example of an endogenous infection?

Escherichia coli entering the bladder and causing a urinary tract infection (UTI).

How can humans acquire normal microbiota?

Through in-utero, the birth canal, food, breathing/touching.

How can the birth canal contribute to a baby's microbiota?

Microbes can be acquired during birth.

How can food contribute to normal microbiota?

Microbes can be acquired through food.

How can breathing and touching contribute to normal microbiota?

People encounter and acquire microbes from their environment.

What is the Human Microbiome Project?

A project that studies the microbial profile inside and on humans.

What is metagenomics used for in the notes?

Identifying the microbial profile inside and on humans.

What is a pathogen?

A microbe whose relationship with its host is parasitic and results in infection and disease

What is pathogenicity?

An organism's potential to cause infection or disease.

What is virulence?

The degree of ability of a microbe to cause disease in another organism.

What determines virulence?

The microbe's ability to establish itself in the host and cause damage.

What is a virulence factor?

any characteristic or structure of the microbe that contributes to its virulence

What is a polymicrobial infection?

An infection involving more than one organism.

What is a communicable organism?

the ability of a disease-causing organism to be spread between individuals

What factors influence whether a microbe causes disease in a particular host?

The pathogenicity of the organism and the condition of its host; virulence, exposure, genetics, and portal of entry also influence the outcome.

How can host condition affect infection?

Different healthy individuals can have widely varying responses to the same microorganism.

How can host genetics affect infection?

Genetics can influence the host's response to a microbe.

What is a true pathogen?

A pathogen that can cause disease in a susceptible host.

What is a portal of entry?

The route through which a microbe enters the body's tissues.

Where do microbes usually enter the body?

Through a cutaneous or membranous boundary, often at anatomical regions that also support normal biota.

What are the major portals of entry discussed in the chapter?

Skin, gastrointestinal tract, respiratory tract, urogenital tract, and placenta or birth canal.

How can microbes enter through the skin?

Through nicks, abrasions, punctures, bites, or other openings.

Why is intact skin an important defense?

Intact skin is very tough, and few microbes can penetrate it.

How can some microbes create passageways through the skin?

By using digestive enzymes or bites.

Which pathogens are listed as examples associated with skin entry?

Staphylococcus aureus, Streptococcus pyogenes, Haemophilus aegyptius, Chlamydia trachomatis, and Neisseria gonorrhoeae.

How do pathogens enter through the gastrointestinal tract?

Through food, drink, and other ingested substances containing pathogens.

What must gastrointestinal pathogens survive to establish infection?

Stomach acid, digestive enzymes, and pH changes.

Which gastrointestinal pathogens are listed in the notes?

Salmonella, Shigella, Vibrio, certain strains of Escherichia coli, poliovirus, hepatitis A virus, echovirus, rotavirus, Entamoeba histolytica, and Giardia lamblia.

What is the respiratory portal of entry?

Entry through the respiratory tract.

Which portal of entry is used by the greatest number of pathogens?

The respiratory portal.

What diseases are listed as examples of respiratory entry?

Streptococcal sore throat, meningitis, diphtheria, whooping cough, influenza, measles, mumps, rubella, chickenpox, the common cold, and some pneumonias.

How do sexually transmitted infections enter the host?

Through the skin or mucous membranes of the penis, external genitalia, vagina, cervix, or urethra.

Can some sexually transmitted pathogens penetrate an unbroken surface?

Yes.

Which sexually transmitted infections are listed in the notes?

Syphilis, genital warts, chlamydia, and herpes.

How can pathogens infect a baby during pregnancy?

Some microbes can cross the placenta.

How can infections occur during birth?

The child can be exposed to microbes in the birth canal.

What does TORCH stand for in the notes?

Toxoplasmosis, other diseases, rubella, cytomegalovirus, and herpes simplex.

What is an infectious dose (ID)?

The quantity of microbes in the inoculating dose.

What is an inoculating dose?

The quantity of microbes introduced into the host.

When does infection usually proceed for most infectious agents?

When the infectious dose is present.

What does a smaller infectious dose indicate?

Microorganisms with smaller infectious doses have greater virulence.

What is the first step in becoming established in a host?

Entering the body's tissues through a portal of entry.

What are phagocytes?

White blood cells that engulf and destroy pathogens.

What are antiphagocytic factors?

Factors used by some pathogens to avoid phagocytes.

What are leukocidins?

Toxins that are toxic to white blood cells.

Which bacteria are listed as producing leukocidins?

Streptococcus and Staphylococcus.

How can an extracellular surface layer help a pathogen?

It makes it difficult for a phagocyte to engulf the pathogen.

Which organisms are listed as examples with an extracellular surface layer?

Streptococcus pneumoniae, Salmonella typhi, Neisseria meningitidis, and Cryptococcus neoformans.

Can some pathogens survive inside phagocytes?

Yes. Some survive inside phagocytes after being engulfed.

Which organisms are listed as surviving inside phagocytes?

Legionella, Mycobacterium, and many rickettsias.

What are extracellular enzymes?

Secreted enzymes that break down and damage tissues or dissolve the host's defense barriers.

What does mucinase break down?

Mucus.

What does keratinase act on?

Keratin.

What does collagenase break down?

Collagen.

What is hyaluronidase?

An extracellular enzyme listed among the enzymes that contribute to tissue damage and the breakdown of host barriers.

What are coagulase and kinases associated with?

Reactions involving components of the blood.

What is a toxin?

A specific chemical product that is poisonous to other organisms.

What is toxigenicity?

The power to produce toxins.

What are toxinoses?

A variety of diseases caused by toxigenicity.

What is toxemia?

A toxinosis in which the toxin spreads through the blood from the site of infection.

Which diseases are given as examples of toxemias?

Tetanus and diphtheria.

What is an intoxication?

A toxinosis caused by ingestion of toxins.

What disease is given as an example of intoxication?

Botulism.

What is the difference between exotoxins and endotoxins shown in the chapter?

The diagram associates exotoxins with being secreted and endotoxins with the outer membrane of Gram-negative bacteria.

Which bacteria are associated with endotoxin?

Gram-negative bacteria.

What can happen when microbes settle in a target organ?

They can continue to cause damage at the site.

How can infection affect host tissues?

It frequently weakens host tissues.

What is necrosis?

Cell and tissue death resulting from accumulated damage.

How can microbes cause damage besides directly damaging tissues?

By inducing an excessive host response.

What is a sign of disease?

Objective evidence of disease noted by an observer.

What is a symptom of disease?

Subjective evidence of disease sensed by the patient.

What is a syndrome?

A disease or condition defined by a particular complex of signs and symptoms.

What are examples of signs or symptoms associated with inflammation in the notes?

Fever, pain, soreness, swelling, edema, granulomas, and abscesses.

What is edema?

Swelling.

What is lymphadenitis?

Inflammation of the lymph nodes.

What is a lesion?

The site of infection or disease.