Very Important Terms for Exam 1!!

Microbiology

Study of microbes with clinical relevance

Prokaryotic cells

Microbial cells without a nucleus; bacteria & archaea

Eukaryotic cells

Microbial cells with a nucleus & organelles; fungi, protozoa, helminths

Viruses

Acellular infectious particles, not true cells

Structures common to all cells

Plasma membrane, cytoplasm, DNA, ribosomes

Prokaryotic ribosome

70S, smaller, antibiotic target (streptomycin)

Eukaryotic ribosome

80S, larger, not affected by streptomycin

Prokaryotic cell wall

Peptidoglycan, Gram + thick vs Gram - thin + LPS

Endospore

Dormant, resistant bacterial structure; germinates in good conditions

Gram positive

Thick peptidoglycan, stains purple

Gram negative

Thin peptidoglycan + outer membrane with LPS, stains pink

Lipid A

Toxic portion of LPS; causes fever, sepsis

Acid-fast bacteria

Waxy mycolic acid layer; Mycobacterium tuberculosis

Granuloma

Tissue wall trapping TB bacteria; necrosis possible

Adhesion structures

Help bacteria stick; fimbriae, pili, slime layers, capsules

Fimbriae

Hairlike proteins with adhesins

Pili

Larger, transfer DNA (conjugation pili), movement (type IV pili)

Biofilm

Community of bacteria in sticky EPS; resistant to antibiotics & immune system

Staphylococcus epidermidis

Normal skin bacteria; forms biofilms on medical devices

Fungi

Eukaryotes; molds (mycelium of hyphae) & yeasts (unicellular)

Dimorphic yeast

Switches mold ↔ yeast (Candida albicans)

Fungal spores

Reproductive cells; dormant, resistant

Mycoses

Fungal infections (superficial, subcutaneous, systemic)

Endemic

Disease regularly found in a region

Prevalence

% of population with disease at a given time

Definitive host

Host where parasite reproduces sexually

Intermediate host

Host where parasite is immature; no sexual reproduction

Giardia cyst

Infective, resistant stage; causes giardiasis ("backpacker's diarrhea")

Giardia symptoms

Diarrhea, nausea, abdominal pain

Toxoplasma definitive host

Cats

Toxoplasma transmission

Undercooked meat, contaminated food/water, cat litter

Latent infection

Dormant infection inside host (Toxoplasma tissue cysts)

Congenital toxoplasmosis

Fetal infection; blindness, miscarriage, deformities

Tapeworm anatomy

Scolex (attachment), neck (growth), proglottids (reproduction)

Beef tapeworm

Humans definitive, cows intermediate

Pork tapeworm

Humans definitive, pigs intermediate

Taeniasis

Intestinal tapeworm disease

Neurocysticercosis

Larval cysts in brain; seizures

Malaria

Caused by Plasmodium, transmitted by Anopheles mosquitoes

Plasmodium sporozoite

Infective stage from mosquito bite

Malaria liver stage

Parasites in liver; may form dormant hypnozoites

Malaria blood stage

Parasites in RBCs; cyclical fever/chills

Uncomplicated malaria

Cyclical fever, chills, sweating every 12-72 hrs

Severe malaria

Cerebral malaria, anemia, organ failure, hypoglycemia, sepsis

Malaria prevention

Nets, repellents, prophylaxis, vaccine (~70-80% effective)