Infection

The growth of a parasitic organism within the body. (A parasitic organism is one that lives on or in another organism and draws its nourishment therefrom.) A person with an infection has another organism (a "germ") growing within him, drawing its nourishment from the person. The term "infection" has some exceptions. For example, the normal growth of the usual bacterial flora in the intestinal tract is not usually considered an infection. The same consideration applies to the bacteria that normally inhabit the mouth.

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Invasion of the body with organisms that have the potential to cause disease.

- agonal i. SYN: terminal i..

- airborne i. a mechanism of transmission of an infectious agent by particles, dust, or droplet nuclei suspended in the air.

- apical i. implantation of microorganisms at the apex of a tooth, usually the result of the migration of microorganisms from the pulp canal through the apical foramen.

- cross i. i. spread from one source to another, person to person, animal to person, person to animal, animal to animal.

- cryptogenic i. bacterial, viral, or other i., the source of which is unknown.

- disseminated gonococcal i. i. from Neisseria gonorrhea which is spread to distant parts of the body beyond the original portal of entry (usually the lower genital tract). Usually manifest by rash and arthritis.

- droplet i. i. acquired through the inhalation of droplets or aerosols of saliva or sputum containing virus or other microorganisms expelled by another person during sneezing, coughing, laughing, or talking.

- endogenous i. i. caused by an infectious agent already present in the body, the previous i. having been inapparent.

- focal i. an old term that distinguishes local infections (focal) from generalized infections (sepsis).

- inapparent i. presence of i. in a host without the occurrence of recognizable symptoms or signs.

- latent i. an asymptomatic i. capable of manifesting symptoms under particular circumstances or if activated.

- mass i. i. resulting from the entrance of a large number of pathogens into the circulation or tissues.

- mixed i. i. by more than one variety of pathogenic microorganisms.

- pyogenic i. i. characterized by severe local inflammation, usually with pus formation, generally caused by one of the pyogenic bacteria.

- Salinem i. SYN: Salinem fever.

- scalp i. an i. external to the galea; e.g., folliculitis or cellulitis.

- secondary i. an i., usually septic, occurring in a person or animal already suffering from an i. of another nature.

- terminal i. an acute i., commonly pneumonic or septic, occurring toward the end of any disease and often the cause of death. SYN: agonal i..

- urinary tract i. (UTI) microbial i., usually bacterial, of any part of the urinary tract; can involve the parenchyma of the kidney, the renal pelvis, the ureter, the bladder, the urethra or combinations of these organs; often the entire urinary tract is affected; the most common organism causing such i. is Escherichia coli.

- vector-borne i. class of infections transmitted by an insect or animal vector. The vector may merely be a passive carrier of the infectious agent, but many kinds of infectious agents undergo a stage in biological development in the vector, i.e., the vector, as well as the human host, is essential to the survival of the infectious agent.

- Vincent i. SYN: necrotizing ulcerative gingivitis.

- zoonotic i. an i. shared in nature by humans and other species of animals.

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in·fec·tion in-'fek-shən n

1) an infective agent or material contaminated with an infective agent

2 a) the state produced by the establishment of an infective agent in or on a suitable host

b) a disease resulting from infection: INFECTIOUS DISEASE

3) an act or process of infecting <syphilis \infection is chiefly venereal> also the establishment of a pathogen in its host after invasion

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n.

invasion of the body by harmful organisms (pathogens), such as bacteria, fungi, protozoa, rickettsiae, or viruses. The infective agent may be transmitted by a patient or carrier in airborne droplets expelled during coughing and sneezing or by direct contact, such as kissing or sexual intercourse (see sexually transmitted disease); by animal or insect vector; by ingestion of contaminated food or drink; or from an infected mother to the fetus during pregnancy or birth. Pathogenic organisms present in soil, organisms from animal intermediate hosts, or those living as commensal on the body can also cause infections. Organisms may invade via a wound or bite or through mucous membranes. After an incubation period symptoms appear, usually consisting of either localized inflammation and pain or more remote effects. Treatment with antibiotics is usually effective against most infections, but there are few specific treatments for many of the common viral infections, including the common cold (see antiviral drug, interferon.

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in·fec·tion (in-fekґshən) 1. invasion and multiplication of microorganisms or parasites in body tissues; it may be clinically inapparent (subclinical infection) or remain localized with cellular injury due to competitive metabolism, toxins, intracellular replication, or antigen-antibody reaction. Infections remain localized, subclinical, and temporary if the body's defense mechanisms are effective. However, they may persist, become symptomatic, and spread by extension to become acute, subacute, or chronic disease states. A local infection may also become systemic when the microorganisms gain access to the lymphatic system or the bloodstream. 2. infectious disease.