CH 5 – Infection

Vocabulary flashcards covering major pathogens, concepts, diseases, clinical terms, diagnostics, and treatments from Chapter 5 Infection lecture notes.

Infection

State of cellular, tissue, and organ destruction resulting from invasion by microorganisms.

Pathogen

Disease-producing microbe that damages host cells directly, alters metabolism, or releases toxins.

Obligate pathogen

Microorganism that must live inside a host cell to survive and reproduce.

Facultative pathogen

Microbe that can live and reproduce inside or outside host cells.

Bacteria

Single-celled prokaryotes capable of independent reproduction; may be gram-positive or gram-negative.

Virus

Obligate intracellular pathogen composed of nucleic acid and protein coat that hijacks host machinery.

Rickettsiae

Small, gram-negative obligate intracellular bacteria transmitted by arthropods (e.g., ticks).

Mycoplasma

Smallest free-living bacteria lacking a cell wall; causes atypical pneumonia and other infections.

Chlamydiae

Obligate intracellular bacteria with a two-stage life cycle; common cause of STIs and pneumonia.

Fungi

Eukaryotic organisms such as yeasts and molds; reproduce by budding or spores.

Protozoa

Single-celled eukaryotes that live independently or as parasites; e.g., Plasmodium in malaria.

Helminths

Parasitic worms (roundworms, tapeworms, flukes) that infect humans.

Chain of infection

Sequence—infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host—needed for disease spread.

Reservoir

Place where a pathogen lives, grows, and multiplies (people, water, equipment).

Portal of entry

Route through which pathogen enters host (respiratory tract, GI tract, broken skin, etc.).

Portal of exit

Pathway by which pathogen leaves reservoir (secretions, excretions, droplets).

Means of transmission

Method by which pathogen spreads (direct contact, ingestion, airborne, fomites).

Susceptible host

Individual at risk of infection due to factors like age, burns, surgery, immunosuppression.

Incubation period

Time between pathogen entry and appearance of first symptoms; patient usually asymptomatic.

Prodrome

Early nonspecific symptoms (fatigue, low-grade fever) signaling onset of disease.

Clinical illness

Phase when characteristic signs and symptoms of a disease are fully expressed.

Convalescence

Recovery phase when symptoms resolve and tissue repair occurs.

Septicemia

Presence and multiplication of pathogens or their toxins in blood causing systemic illness.

Bacteremia

Bacteria present in bloodstream; may progress to septicemia.

Septic shock

Severe systemic infection leading to hypotension, organ failure, and high mortality.

Leukocytosis

Elevated white blood cell count, often indicating infection or inflammation.

Leukopenia

Abnormally low white blood cell count, increasing infection risk.

Antimicrobial drug

Medication that kills or inhibits growth of microbes (antibacterial, antifungal, antiviral).

Shingles (Herpes zoster)

Reactivation of latent varicella-zoster virus producing painful dermatomal rash.

Dermatome

Skin area supplied by a single spinal nerve; site of shingles rash.

Influenza

Acute viral infection of airway epithelium causing fever, cough, myalgia; spreads via droplets.

Reassortment

Gradual genetic change in influenza virus during replication, leading to new strains.

Rapid viral assay

Point-of-care swab test that detects influenza antigens within minutes.

Viral hepatitis

Inflammation of liver due to hepatitis viruses A–E, resulting in hepatic necrosis.

Hepatitis A virus (HAV)

Fecal-oral transmitted virus causing acute, self-limited hepatitis; vaccine available.

Hepatitis B virus (HBV)

Blood/body-fluid transmitted virus that can become chronic; vaccine available.

Hepatitis C virus (HCV)

Blood-borne virus often leading to chronic hepatitis and cirrhosis; no vaccine.

Hepatitis D virus (HDV)

Defective virus requiring HBV coinfection; blood-borne; chronic infections common.

Hepatitis E virus (HEV)

Fecal-oral transmitted virus causing acute hepatitis; no chronic carrier state or vaccine.

Icterus

Phase of hepatitis marked by jaundice, dark urine, and clay-colored stools.

Jaundice

Yellow discoloration of skin and sclera due to elevated bilirubin.

Tuberculosis (TB)

Airborne infection by Mycobacterium tuberculosis forming lung granulomas; may remain latent.

Mycobacterium tuberculosis

Acid-fast bacillus causing tuberculosis; often drug resistant.

Ghon complex

Calcified primary lung lesion plus involved lymph node seen in healed TB.

Urinary tract infection (UTI)

Ascending bacterial infection (usually E. coli) of urethra, bladder, or kidneys.

Dysuria

Painful or difficult urination, common in UTIs.

Leukocyte esterase test

Urine dipstick detecting WBC enzyme; indicates pyuria in UTI.

Acute pyelonephritis

Bacterial infection of renal pelvis and kidneys causing fever and flank pain.

Costovertebral angle pain

Tenderness over flank between spine and ribs; hallmark of kidney infection.

Bacterial meningitis

Rapid inflammation of brain and spinal cord meninges, often by N. meningitidis.

Kernig sign

Pain and resistance when extending knee with hip flexed; indicates meningeal irritation.

Brudzinski sign

Involuntary hip/knee flexion when neck is flexed; suggests meningitis.

Tinea

Dermatophyte fungal infection of keratinized tissues; commonly called ringworm.

Dermatophyte

Fungus that invades skin, hair, or nails and digests keratin.

Malaria

Mosquito-borne protozoal disease by Plasmodium species causing cyclical fevers.

Plasmodium

Protozoan genus (e.g., P. falciparum) responsible for malaria.

Quinoline drugs

Antimalarial agents (e.g., chloroquine) that interfere with parasite heme detoxification.

Artemisinins

Fast-acting antimalarial drugs derived from Artemisia annua used in combination therapy.