Medical Micro Flashcards
What are macrophages?
Cells that engulf bacteria
very non specific
Engulfs anything
Tons patrolling on the skin
What types of innate non specific defenses do hosts have against pathogenic organisms?
Cellular/ humoral ( secretions) components
Macrophages
Lysozyme s
Anatomical barriers
Skin, mucus membranes
Biological barrier: competition with micro flora
What are some acquired, specific defenses against pathogens?
Cellular- T cells, B cells Humoral- antibodies, very selective Memory Cell cooperation- innate and acquired cells work together Phagocytosis
What is phagocytosis?
Process by which phagocytic cells (monocytes, tissue macrophages, dendritic cells, neutrophils)recognize, ingest and kill extra cellular microbes.
What is the first line of defense against pathogens?
Mucus membranes
What are some ways pathogens attempt to evade detection and destruction?
Different Capsules
Shapeshifters- vary LPS proteins
Some don’t become pathogenic till they find a suitable environment
What are exotoxins?
Released from bacterium and acts on host cell from a distance Protein Soluble and secreted Gram +/- Can be denatured at high heat Most potent poisons known Highly specific Anthrax
What are toxoids and where do they come from?
Denatured exotoxins that can be used to make vaccines
Non virulent
What are endotoxins?
Gram - only
LPS on gram - cell wall- 3 parts of the LPS
O polysaccharide can be varied to avoid detection
Lipid A is the toxic part of the LPS, creates a massive immune system response
Must be careful when treating to maintain a slow release of the lipid A as the cell dies, can kill if too much is released
What are. Pathogenicity islands?
Parts of the genome that code for pathogenicity
Can be acquired by horizontal gene transfer in many different species
A non pathogenic strain will not have the sequence while a pathogenic strain of same species will
Exo and endo toxins differ in that..
Only gram - make endotoxins
Exotoxin is destroyed by heat but endotoxins is not
What microbes cause skin infections?
Staphylococcus A S. epidemis S. aureus S. pyrogens Mycobacterium leprae
What conditions are staphylococcus Aureus (staph A) involved in?
Pneumonia Endocarditis Bacteremia Staph scalded skin syndrome MRSA TSS Impetigo Foliculitis pimple, sty, furnucle, carbuncle Necrotizing fasciitis ( also caused by group A strep) Erysipelas
What are the virulence factors of staph A?
Coagulase Hyaluronidase Staphylokinase Lipases B- lactamase Capsule Protein A Toxins
What are antibiotic s mechanisms of action?
Inhibition if nucleic acid synthesis Inhibition of protein synthesis Action on cell membrane Interference with enzyme systems Action on bacterial cell wall
How does antibiotic resistance develop?
Spontaneous mutation
Horizontal gene transfer
What the mechanisms of bacterial resistance to antibiotics?
Reduced uptake into cell
Active efflux of antibiotic from the cell
Eliminate or reduce binding of antibiotic to cell target
Enzymatic cleavage or chemical modification inactivated antibiotic molecule
Metabolic bypass of inhibited reaction
Overproduction if antibiotic target
What are some strategies to find new antibacterial compounds?
Screening bacterial and fungal species for antimicrobial activity
Semi synthetic antibiotics are made by derivitizing natural antibiotics
Synthetic antibiotics are serendipitously discovered or designed intelligently to bind to bacteria in a specific way
What are seem ways to combat antibiotic resistance?
Pharmaceutical companies need new low cost strategies to develop antimicrobials
Regulate use of antibiotics as feed additives, livestock use
Stop putting antibiotic resistant genes into GMO s
Stop administration and uses of antibiotics for viral infections and non medical purposes
Finish antibiotic prescriptions
What one of toxin does staph a secrete? Is it gram positive or negative
Exotoxins- have A and B parts, part A binds while part B is the toxin
Gram +
Resistant to salt , heat, uv desiccation
What do both staph and strep have?
Exotoxins, both are gram +
What bacterium is responsible for leprosy ( hansons disease)? And why is it special?
Mycobacterium leprae
Mycobacterium s are gram + bacillus with a waxy lipid cell wall (mycolic acid) that grows very slowly
Cell wall protects it from lysis, antimicrobial drugs, detergents
How is hansons disease spread?
Person to person Inhalation of respiratory droplets Breaks in skin Not very virulent Only passed only after years of frequent intimate contact
What causes strep throat?
Group A strep, S. pyogenes
