Module 5 Flashcards
transient microorganisms
pass through host without causing harm or establishing residence
commensal
established residency in host but do not cause harm, may be beneficial
- normal flora
physical and mechanical barriers of host
epithelial cells
- skin: inhabits bacterial and fungal growth
- Gi/GU: mucous membranes trap microorganisms and remove them
- respiratory tract: mucociliary system sweeps organisms up and out
biochemical barriers of host
acidic environment
acid in stomach
antimicrobial chemcials
impaired immune system can be due to
immunosuppressive drugs inflammatory disorders poor nutrition young or old age chronic illness
Pathogen characteristics
adherence and invasion bacterial endotoxin bacterial exotoxin evasion of immune cells antimicrobial resistance
Endotoxin
in cell well, gram negative. lipopolysaccharides released when cell is destroyed.
exotoxin
toxin secreted by bacteria, gram positive
released during bacterial growth
evasion of immune cells
coating on surface prevents phagocytosis
biofilm: bacteria uses host to create capsule and hide.
bacteria
singe-celled, rigid-walled organisms with no internal organs
shapes of bacteria
cocci: spherical (clusters, chains, pairs, tetrads)
bacilli: rod shaped
spiral
sprochetes
bacteria that possess motile spiral filament
mycoplasma
smallest bacteria, no rigid wall and pleomorphic
Rickettsia:
intracellular parasites with variety of shape
chlamydia
intracellular parasite with complex life cycle
gram positive
thick cell wall, peptidoglycan layer. stains purple
gram negative
thin cell wall
nutritional requirements of bacteria
anaerobic
aerobic
colonization of bacteria
require adhesion: limits sites where bacteria can colonize.
fungi
eukaryotic microorganisms with complex structures and thick, rigid cells walls. Do have organelles.
dermatophytes
fungi in skin, hair, and nails
deep fungal infections
life threatening due to similar make up to host cells. Medications also kill host cells.
parasites
range from small unicellular protozoan to large worms.
4 families of parasites
protozoa: single celled
nemathelminths: round worms
platyhelminths: flat worms
arthropoda: invertebrate with jointed appendages.