Module 4-Lesson1&2

Pili or Fimbriae

Long, thin, hair-like, flexible projections composed primarily of an array of proteins called 'pilin' that enable bacteria to attach to surfaces including various tissues within the human body.

Capsule

A form of glycocalyx that has an antiphagocytic action, allowing adherence.

Flagella

Threadlike projections used for locomotion or mobility.

Bacterial Toxins

Poisonous substances produced by certain microorganisms considered as the primary factor that contributes to the pathogenic properties of those microbes.

Exotoxin

Proteins produced inside pathogenic bacteria, which are secreted into the surrounding medium.

Endotoxins

Constitutive elements of the bacteria membrane that liberate when the bacteria die, usually found on the outer membrane of gram-negative bacteria.

Exotoxins Characteristics

Excreted by living cells; high concentrations in liquid medium; relatively unstable; toxicity often destroyed rapidly by heating at temperatures above 60°C.

Endotoxins Characteristics

Integral part of the cell wall of Gram-negative bacteria; released on bacterial death and in part during growth; may not need to be released to have biologic activity.

Toxoids

Converted from exotoxins to antigenic, nontoxic forms by formalin, acid, heat, and so on; used to immunize (e.g., tetanus toxoid).

Diphtheria toxin

Exotoxin produced by Corynebacterium diphtheriae.

Tetanospasmin

Exotoxin produced by Clostridium tetani.

Botulinum toxin

Exotoxin produced by Clostridium botulinum that can cause paralysis.

Exotoxin A and B

Exotoxins produced by Clostridium difficile.

Alpha toxin

Exotoxin produced by Clostridium perfringens that causes hemolysis of RBCs, edema, and cell death.

Edema factor, lethal factor & protective antigen

Exotoxins produced by Bacillus anthracis.

TSST

Toxic Shock Syndrome Toxin produced by S. aureus and S. pyogenes.

Lipopolysaccharide

Complexes with a lipid A portion probably responsible for toxicity.

Antitoxin

Antibodies produced for the toxins that neutralize the toxin.

Gram-negative bacteria

Bacteria that have an outer membrane and are characterized by the presence of endotoxins.

Gram-positive bacteria

Bacteria that do not have an outer membrane and can produce exotoxins.

Microbial Quantities

Exotoxins can be fatal to animals in microorganism quantities or less.

Toxicity Stability

Endotoxins are relatively stable and can withstand heating at temperatures above 60°C for hours without loss of toxicity.

Vagina

Anatomical structure that hosts lactobacilli, which appear soon after birth and persist.

Urethra

Anatomical structure containing small numbers of organisms found on the skin and perineum.

Conjunctiva

Mucous membrane whose flora is normally held in check by tears containing antibacterial lysozyme.

Lactobacillus

A type of bacteria that appears in the vagina after birth.

E. coli

A common bacterium that can be part of the normal flora but may become pathogenic.

Group B streptococci

A type of bacteria that can be part of the normal flora.

Diphtheroid

A type of bacteria, such as Corynebacterium, that can be part of the normal flora.

S. epidermidis

A type of bacteria that is part of the normal flora but can become pathogenic if displaced.

Opportunistic Pathogens

Organisms that do not cause disease in their normal habitat but may do so in a different environment.

Symptoms

Subjective changes felt by the patient that are not apparent to the physician.

Disease

A condition where an individual is infected, resulting in a change in health status.

Infection

A disease primarily caused by pathogenic microorganisms.

Communicable Disease

A disease that is spread from one person to another.

Contagious Disease

A highly communicable disease.

Non-Communicable Disease

A disease that is not transmitted from one host to another.

Incidence

Measure of new cases of a disease, indicating the spread of disease.

Prevalence

Includes all cases of a disease, both old and new.

Signs

Objective changes that can be measured and observed by a physician.

Sporadic Disease

A disease that occurs only occasionally within a specific population.

Benefits Derived from Normal Microbiota

First line of defense against pathogens, assist in digestion, and contribute to immune system maturation.

Tuberculin Skin Test

A test where tuberculin is injected, leading to induration and redness if previously exposed to Mycobacterium tuberculosis.

Malaise

A general feeling of discomfort or unease.

Asymptomatic/Carrier

Individuals who are infected but do not show symptoms of disease.

DELAYED-TYPE HYPERSENSITIVITY (DTH)

An immune response that occurs hours to days after exposure to an antigen, exemplified by the tuberculin skin test.

Microbiota

Microbes that are present for a short time and don't cause disease.

Sterile parts

Areas of the body that are absent of microbiota, such as blood, cerebrospinal fluid (CSF), joint fluid, and internal organs.

The Mantoux skin test

Consists of an intradermal injection of 1/10 mL of PPD tuberculin, resulting in a circular wheal response.

Resident microbiota

Permanent microorganisms that, if disturbed, promptly reestablish themselves.

Transient microbiota

Temporary microorganisms that inhabit body sites for hours, days, or weeks, and can be non-pathogenic or potentially pathogenic.

Commensalism

A type of symbiotic relationship where one organism benefits and the other is unaffected.

Mutualism

A type of symbiotic relationship where both organisms benefit from each other.

Parasitism

A type of symbiotic relationship where one organism benefits at the expense of the other.

Staphylococcus epidermidis

Bacteria commonly found on the skin that exemplifies commensalism.

Influenza viruses

Viruses that benefit by infecting host cells, exemplifying parasitism.

Carriers

Persons that harbor pathogens and transmit them to others without exhibiting any signs of illness.

Passive Carrier

A person who is capable of transmitting a pathogen without ever having had the disease.

Incubatory Carrier

A person who is capable of transmitting a pathogen during the incubation period of a particular disease.

Convalescent Carrier

A person who harbors and can transmit a pathogen while recovering from a disease.

Active Carrier

A person who has completely recovered from the disease but continues to harbor the pathogen indefinitely.

Pathology

The study of disease.

Etiology

The cause or origin of the disease.

Pathogenesis

The steps or mechanisms involved in the development of a disease.

Pathogenicity

The ability of a microorganism to cause disease.

Portal of Exit

A way for the pathogen to escape from the reservoir, with definite routes of exit related to the infected part of the body.

Stages of Bacterial Pathogenesis

Include transmission from an external source into the portal of entry, evasion of primary host defenses, adherence to mucous membranes, colonization or growth, and disease symptoms caused by toxin production or invasion.

Mode of Transmission

A way for the pathogen to travel from one host to another.

Contact transmission

A principal route through which pathogens can be transmitted.

Vehicle transmission

A principal route through which pathogens can be transmitted.

Vector transmission

A principal route through which pathogens can be transmitted.

Portal of Entry

A way for the pathogen to gain entry into a host.

Virulence

A quantitative measure of pathogenicity and is measured by the number of organisms required to cause a disease.

Highly virulent

Can cause a disease, leads to severe type of disease.

Low virulent

Can still cause a disease, but it may not progress to a severe type of disease.

Avirulent organisms

Not capable of causing disease.

Virulence Factors

Phenotypic characteristics or physical attributes of pathogens that enable them to escape various host defense mechanisms and can cause disease.

Endemic Disease

A disease that is always or constantly present at low level in a specific population.

Epidemic Disease

An 'outbreak,' a disease that occurs much more frequently than usual in a particular region usually occurring within a relatively short period.

Pandemic Disease

A disease that has a worldwide distribution.

Secondary Infection

An infection caused by an opportunistic microorganism after the primary infection has weakened the body's defenses.

Inapparent or Subclinical Infection

An infection that results in overt symptoms and can be detected only by demonstrating a rise in antibody titer or by isolating the microorganism.

Acute Infection

It develops rapidly and lasts only for a short period of time.

Chronic Infection

It develops more slowly (gradually) and lasts for long periods of time.

Pathogen

The microorganism causing the infection or disease.

Reservoir

The source of the pathogen or the disease-causing microorganism.

Human Reservoir

The most important reservoir of human disease.

Animal Reservoir

Both wild and domesticated animals are living reservoirs.

Nonliving Reservoir

The inanimate major reservoir of infectious diseases.

Local Infection

One in which the invading microorganisms are limited to a relatively small area of the body.

Systemic Infection

One in which the invading microorganisms are spread throughout the body.

Focal Infection

A local infection that later develops into a systemic infection.

Primary Infection

An acute infection that causes the initial illness or disease.

Zoonoses

Zoonotic diseases are diseases that humans acquire from animal sources.