Introduction to microbiology - basic terminology

Abscess

Localization of puss (segmented neutrophils) in a walled off area

Acute infection

Infection with sudden onset and usually shorter duration

Bacteremia - presence of bacteria in blood

Can be transient - “just passing through” and temporary (like flossing)

Or can be Septicemia - bacteremia with multiplication of bacteria and host signs / symptoms

Carriers / carrier state

A host harboring a pathogen without manifesting symptoms (and they can still transmit the pathogen)

Cellulits

Involvement and spreads between layers of subcutaneous tissues

Chronic infection

a long standing infection

CDC

Centers for Disease Control and Prevention (based in Atlanta, GA)

Colonization

Population of a body site with organisms that are not causing disease

Commensal

one benefits but no harm to other

Dissemination

Spread of infection to distant sites

Edema

Accumulation of fluid in tissues due to increased vascularization (swelling)

Endemic

Disease or organism indigenous to a certain geographic area

Endogenous infection

infection from host’s own flora (peritonitis, urinary tract infection, etc)

Epidemic

disease affecting large number of people in a geographical area

Erythema

redness (indicating increased blood flow to area)

Exogenous infection

When an agent is acquired from outside of host’s body

Flora

“usual””normal”: indegenous, frequently found in that body site in healthy individuals

Granuloma

chronic inflammation with collection (mass) of macrophages, usually forming small nodules

Iatrogenic infection

occurs as a result of medical procedure (transplant, urine catheterization, etc)

Invasion / invasiveness

ability to penetrate and grow in tissues (may be local or disseminated)

Latent infection

Infectious agent is present, but not active

Morbidity

number of cases of a disease

Mortality

number of deaths caused by a disease

Necrosis

Cell/ tissue death, usually caused by enzymes or restriction of blood flow

Nosocomial

hospital aquired

opportunistic pathogen

cause disease only if host is compromised

Parasite

One organism benefits at expense of another (small % of bacteria are parasitic)

Pathogen (pathogenic) or virulent

capable of causing disease

symbiotic

both benefit

true pathogen

cause disease in healthy, immune competent individuals

Virulence

ability to cause disease (lower infective dose = more virulent)

Zoonotic

acquired from contact with animals