Chapter 6 – Infection

Vocabulary flashcards summarizing key terms and concepts from Chapter 6 – Infection lecture notes.

Microorganisms

Small living forms including bacteria, fungi, protozoa, and viruses

Nonpathogenic

Normally harmless microbes that do not cause disease unless conditions change; part of normal flora

Pathogen

Disease-causing microorganism

Prokaryote

Simple cell without a nucleus; all bacteria are prokaryotes

Binary fission

Asexual bacterial reproduction producing two identical daughter cells

Bacillus

Rod-shaped bacterium

Spirochete

Spiral-shaped bacterium that includes vibrio and spirilla forms

Coccus

Spherical bacterium

Diplococci

Pairs of cocci

Streptococci

Chains of cocci

Staphylococci

Clusters of cocci

Gram-positive bacteria

Bacteria with thick peptidoglycan wall that retain crystal violet stain

Gram-negative bacteria

Bacteria with thinner wall and outer membrane that do not retain crystal violet stain

Capsule (slime layer)

External mucous coating that provides additional bacterial protection

Flagella

Whip-like structures used for bacterial motility

Pili (fimbriae)

Hair-like appendages aiding attachment and DNA transfer

Plasmid

Small non-chromosomal DNA fragment exchanged during conjugation

Exotoxin

Toxin secreted by living gram-positive bacteria

Endotoxin

Toxin in gram-negative cell wall released on bacterial death

Bacterial enzymes

Proteins that damage tissue and help infection spread

Spore

Dormant, highly resistant bacterial form that survives extreme conditions

Virus

Small obligate intracellular parasite made of nucleic acid and protein coat

Capsid

Protein coat enclosing viral nucleic acid

Reverse transcriptase

Viral enzyme that converts RNA to DNA

Active viral infection

Virus controls host cell to replicate and release new virions

Latent viral infection

Viral genome persists silently and can reactivate when immunity drops

Chlamydia

Obligate intracellular bacterium causing sexually transmitted infection and possible infertility

Rickettsiae

Small gram-negative bacteria transmitted by insect vectors

Mycoplasmas

Cell-wall-lacking bacteria causing atypical pneumonia

Fungi

Eukaryotic organisms such as yeasts and molds

Mycotic infection

Disease caused by fungi

Histoplasma

Fungus that can cause neurologic disease and fetal infection

Tinea pedis

Fungal infection known as athlete’s foot

Candida albicans

Opportunistic yeast causing thrush and vaginitis

Pneumocystis jirovecii

Opportunistic organism causing pneumonia with fungal-like traits

Protozoa

Unicellular eukaryotes lacking cell walls; often parasitic

Trichomoniasis

Sexually transmitted infection by Trichomonas vaginalis

Malaria

Disease caused by Plasmodium species infecting red blood cells

Amebic dysentery

Intestinal infection by Entamoeba histolytica

Naegleria fowleri

Protozoan causing fatal brain infection

Helminth

Parasitic worm (flatworm or roundworm)

Pinworm

Small helminth whose ova are inhaled from contaminated dust

Hookworm

Helminth whose larvae penetrate skin from contaminated soil

Tapeworm

Helminth transmitted by larvae in undercooked pork or other meats

Ascaris lumbricoides

Giant roundworm acquired from feces-contaminated food or soil

Prion

Abnormal protein that induces misfolding, causing fatal neurodegeneration

Resident flora

Normal mixed population of microbes living on or in the body

Infection

Presence and reproduction of an organism in host tissues

Sporadic infection

Disease occurring in a single individual

Endemic infection

Continuous transmission within a population

Epidemic

Higher-than-normal infection rates or spread to new areas

Pandemic

Epidemic occurring on most continents

Reservoir

Source of an infectious agent

Carrier

Individual harboring a pathogen without symptoms

Portal of exit

Pathway by which a pathogen leaves its reservoir

Portal of entry

Route through which a pathogen enters a host

Fomite

Inanimate object that transfers pathogens indirectly

Direct contact

Transmission without intermediary, e.g., touching, sexual activity

Droplet transmission

Spread via large respiratory or salivary droplets

Aerosol transmission

Spread via tiny airborne particles that travel farther than droplets

Vector-borne transmission

Disease spread by insect or animal acting as intermediate host

Nosocomial infection

Infection acquired in a health-care facility

Virulence

Degree of pathogenicity of a microbe

Pathogenicity

Capability of a microbe to cause disease

Superinfection

Multidrug-resistant infection emerging during or after therapy

Standard precautions

Basic infection-control measures used with all patients

Incubation period

Time between pathogen entry and appearance of signs

Prodromal period

Early nonspecific symptoms before acute illness

Leukocytosis

Elevated white blood cell count typical of bacterial infection

Leukopenia

Reduced white blood cell count often seen in viral infection

Bactericidal drug

Antimicrobial that kills bacteria

Bacteriostatic drug

Antimicrobial that inhibits bacterial reproduction

Broad-spectrum antibiotic

Drug effective against both gram-positive and gram-negative bacteria

Narrow-spectrum antibiotic

Drug effective against a limited group of bacteria

Autoclave

Device using heat and pressure to sterilize equipment

C-reactive protein (CRP)

Blood marker elevated in inflammation or infection

Erythrocyte sedimentation rate (ESR)

Test measuring red cell settling to indicate inflammation

Minimal inhibitory concentration (MIC)

Lowest drug concentration that prevents visible microbial growth

Exudate

Fluid from inflammation; purulent in bacterial, serous in viral infections

Antiviral drug

Medication that blocks viral entry, gene expression, or assembly

Antifungal agent

Drug that interferes with fungal mitosis or membrane permeability

Antiprotozoal agent

Medication targeting protozoan pathogens, often stage-specific