Chapter 13: Comprehensive Biology Notes: Microbial Pathogenicity, Infection Stages, and Epidemiology

Vocabulary practice flashcards covering basic microbiology concepts including biota, pathogenicity, stages of infection, and epidemiology.

Normal Biota

A term used to refer to the collection of microbes that live on and in the human body without usually causing disease.

Resident Biota

A synonym for the microorganisms that have established long-term colonization of the human body.

Indigenous Flora

Another name for the normal microbiota inhabiting the human body.

Microbiome

The collective name for the genomes of the microbes that reside in an environmental niche such as the human body.

Favorable Habitat Conditions

Conditions including stable temperature, consistent $pH$, moisture, and abundant nutrients that make the human body ideal for microbes.

Viral Normal Residents

Evidence suggesting that viruses are permanent and common residents of the human body, not just transient invaders.

Probiotics

Preparations of live microbes that are consumed to improve or restore the health of the intestinal biota.

Axenic

A term used to describe a state or environment that is completely free of any microbes or other living organisms.

Pathogenicity

The broad ability or capacity of a microorganism to cause infection and disease in a host.

True Pathogen

A microbe capable of causing disease in healthy persons with normal immune defenses.

Opportunistic Pathogen

A microbe that causes disease only when the host's immune system is compromised or when it enters an unusual body site.

Portal of Entry

The specific route or site through which a pathogen enters the body to initiate an infection.

Skin Portals of Entry

Means of entry including nicks, abrasions, punctures, or enzymes that digest the outer layers of the tissue.

Gastrointestinal (GI) Portals of Entry

Pathogens that enter via food or drink and must survive the low $pH$ of the stomach and digestive enzymes.

Infectious Dose

The minimum number of microbial cells or particles, often abbreviated as $ID$, required to cause an active infection in a host.

Adhesion

The process where microbes gain a stable foothold on host tissues using structures like fimbriae or surface proteins.

Virulence Factor

Any characteristic or structure of a microbe that contributes to its ability to establish itself in a host and cause damage.

Exoenzymes

One of the three categories of virulence factors; these are enzymes secreted by pathogens to break down host tissues.

Toxins

A category of virulence factors consisting of poisonous chemical products produced by microorganisms.

Antiphagocytic Factors

A category of virulence factors used by pathogens to avoid or survive the response of host white blood cells.

Direct Damage

Damage caused by pathogens through the action of enzymes or toxins that physically break down host cells and tissues.

Initial Resistance

The first encounter between a non-normal microbe and the host's defenses, primarily involving the phagocytic response.

Phagocyte

A type of white blood cell that targets, engulfs, and destroys foreign microbes via specialized chemicals and enzymes.

Leukocidins

Toxic substances produced by some bacteria that specifically target and kill host white blood cells.

Extracellular Surface Layer

Structures like capsules or slime layers that prevent a phagocyte from successfully engulfing a pathogen.

Intracellular Survival

The ability of some pathogens to be engulfed by a phagocyte but avoid destruction and continue to multiply within it.

Exoenzyme (Definition)

An extracellular enzyme secreted by a microbe to facilitate the invasion of host tissues by dissolving barriers.

Toxin (Definition)

Any specific chemical product of microbes, plants, or animals that exerts a poisonous effect on other organisms.

Toxinoses

A broad category of diseases resulting from the adverse effects of toxins released by microbes.

Toxemia

A type of toxinoses where the toxin is spread through the blood from the site of the infection.

Intoxication

A toxinoses caused by the ingestion of a toxin rather than the presence of the microbe itself.

Exotoxin

A toxin molecule secreted by a living bacterial cell into the surrounding environment or host tissue.

Endotoxin

A toxin that is not actively secreted but is released after the bacterial cell is damaged or lysed.

Lipopolysaccharide (LPS)

The specific chemical component of the outer membrane of certain bacteria that acts as an endotoxin.

Gram-negative Bacteria

The classification of bacteria that possess an outer membrane containing Lipopolysaccharide ($LPS$).

Typical Stages of Infection

The sequence of events consisting of incubation, prodromal stage, invasion, and convalescence.

Incubation Period

The time from the initial contact with an infectious agent to the first appearance of symptoms.

Prodromal Stage

The short period of earliest, vague symptoms, such as malaise or head and muscle aches.

Period of Invasion

The stage of infection where the pathogen multiplies at high levels and exhibits its greatest toxicity in the host.

Convalescent Period

The phase of recovery where the host's health gradually returns as the symptoms of the infection decline.

Localized Infection

An infection in which the microbe enters the body and remains confined to a specific tissue or site.

Systemic Infection

An infection that spreads to several sites and tissue fluids through systems like the bloodstream.

Focal Infection

Occurs when an infectious agent breaks loose from a local infection and is carried by the blood to another specific tissue.

Mixed (Polymicrobial) Infection

An infection involving several different microbes that establish themselves simultaneously at the same site.

Primary Infection

The initial infection in a host that may be followed by a secondary infection.

Secondary Infection

An infection that occurs when a primary infection is complicated by a different microbe.

Acute Infection

An infection characterized by a rapid onset and severe but short-lived effects on the host.

Chronic Infection

An infection that progresses and persists over a long period or duration of time.

Symptom

Subjective evidence of a disease as sensed and reported only by the patient.

Sign

Objective and measurable evidence of a disease as noted by an outside observer.

Signs vs. Symptoms

Signs are objective findings like fever or swelling, while symptoms are subjective feelings like pain or nausea.

Syndrome

A specific group of signs and symptoms that characterize a particular disease or condition.

Inflammation

A host response to tissue damage characterized by redness, pain, heat, and swelling.

Edema

An inflammatory sign consisting of the accumulation of fluid in afflicted tissues resulting in swelling.

Granulomas and Abscesses

Signs of inflammation consisting of walled-off collections of inflammatory cells and microbes in the tissues.

Lymphadenitis

A sign of infection involving the swelling or enlargement of the lymph nodes.

Leukocytosis

A sign of blood infection characterized by an increase in the level of white blood cells.

Leukopenia

A sign of blood infection characterized by a decrease in the level of white blood cells.

Septicemia

A general state where microorganisms are actively multiplying in the blood and present in large numbers.

Bacteremia

A condition where small numbers of bacteria are present in the blood but are not necessarily multiplying.

Viremia

The clinical condition where viruses are present in the circulating blood of a host.

Asymptomatic Infection

An infection where the patient experiences no noticed symptoms and does not seek medical attention.

Portal of Exit

A specific avenue by which a pathogen leaves the host to spread to other organisms.

Latency

A state of persistence where an infectious agent remains in a dormant state after the initial symptoms have cleared.

Epidemiology

The study of the frequency and distribution of disease within defined human populations.

Reservoir

The primary natural habitat from which a pathogen originates, such as soil, water, or an animal host.

Carrier

An individual who shelters a pathogen and spreads it to others without showing any outward signs of disease.

Surveillance

The process of collecting, analyzing, and reporting data relating to the occurrence of diseases.

Prevalence

The total number of existing cases in an entire population, usually expressed as a percentage of the population.

Health-care-associated Infection (HAI)

An infection that is acquired or developed during a stay in a hospital or medical facility.