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.
parasite transmission
vector
- mosquitoes
- water/food
- oral
viruses
smalles infectie angents consist of: - protein shell: capsid - core genetic material (RNA or DNA) - some have protective envelope encircling capsid
classification of viruses
DNA or RNA
Double or single stranded
Retrovirus: contains enzyme reverse transcriptase
reverse transcriptase
converts RNA to DNA
obligate intracellular parasite
viruses require host
zoonotic
animal reservoir of virus
CCR5- delta 32 gene
natural immunity to HIV, especially with both genes mutated
chain of transmission of microorganism
Reservoir: human animal insect soil
Portal of exit: nasal mucosa, oral mucosa
Mode of transmission: insect bite, nasal droplets, semen
Portal of entry: nasal mucosa, oral mucosa, skin abrasion, skin puncture, sex
Susceptible victim: malnourished, unimmunized, immune compromised.
bacteria classified by (2) and then further differentiated by (3)
morphology and gram staining
nutritional requirements, colony characteristics, resistance patterns
HIV p24 contains 2(blank) and 3 enzymes
RNA
protease
integrase
reverse transcriptase
gp120 and gp41
Have similar characteristics to MHC, immune system does not recognize them.
pediatric Dx of HIV
personal hx, viral culture, clinical manifestations.
- CNS is particularly vulnerable: developmental delays, impaired brain growth, motor deficits.
