Unit 1- Resistance Flashcards
Therapeutic Antimicrobials
Used to treat an individual when they are sick
Metaphylactic Antimicrobials
Treat the entire herd when one patient is sick
Prophylactic Antimicrobials
Seasonal prescription of a drug to prevent infection of the most susceptible population
Growth Promotion Antibiotics
Increases weight gain, banned in EU and USA
Biofilms
Bacteria are hibernating until conditions are good to continue growing, highly resistant in this stage
Plankton
Living moving phase of life
Classical Gram +
Several layers of peptidoglycan in cell wall with lipoic acid
Mycobacterium
Peptidoglycan in cell wall is covered by mycolic acid
Classical Gram -
Outer membrane is made up of proteins and LPS
Chlamydia
Cell wall without peptidoglycan and outer membrane with proteins and LPS
Mycoplasma
No cell wall, sterols in cell membrane
Targets of Antimicrobials
Cell wall synthesis, folic acid synthesis, protein synthesis, mRNA, DNA synthesis
Antimicrobial Resistance Mechanisms
reduced membrane permeability, efflux pumping, drug inactivation by enzymes, target site modification
Biofilm Protection
Extracellular matrix, thick communities, low nutrient and oxygen supply, dormant cell in center
Tetracycline AMR
Acquire efflux transporter genes or increase expression to pump drugs out of cytoplasm
Chloramphenicol AMR
Change 50S drug target site
Rifamycin AMR
Change RNA polymerase drug target site
Quinolones AMR
Change Topoisomerase drug target site
Beta Lactam AMR
Enzymes that destroy or modify drugs encoded by plasmids
Amonoglycoside AMR
Enzymes that destroy or enzymatically modify the drug encoded by plasmid
Beta Lactam AMR in G+
Change in binding site of beta lactams
Beta Lactam AMR in G-
Beta lactamase enzyme production
ESBL Plasmid
Conveys resistance to penicillin, cephalosporin, and monobactam
Carbapenemase Plasmid
Conveys multidrug resistance to all beta lactams
Vertical Gene Transfer
Resistance is acquired from parent cells
Horizontal Gene Transfer
Resistance is acquired from free DNA in nature, plasmids, or bacterophages
Guidelines for AMR detection
CLSI, EUCAST, or ISO
ESKAPE
Top AMR species: Enterococcus, S. aureus, K. pneumonidae, A. baumannii, P. aeruginosa, Enterobacter
Fast Growing 24 hour species
Enterobacteriaceae, other gram negative bacilli, and non fastidious gram positives
Slow growing species that need special media
Fastidious organisms, bioterrorism agents, and anaerobic microbes
Mannitol salt agar
Used for Staphylococcus, enterococcus, listeria, and micrococcaceae
Edward media
Used for Streptococcus and Enterococcus
Kenner-fecal agar media
Selective media for Enterococcus
MacConkey agar
Used for Enterobacteriaceae and Enterococcus
Aerobic Bacteria Broth Media
Cation-adjusted Mueller-Hinton
Aerobic Bacteria Agar Media
Cation-adjusted Mueller-Hinton
Anaerobic Bacteria Broth Media
brucella broth + hemin, vitamin K, and horse blood
Anaerobic Bacteria Agar Media
Brucella blood agar + hemin, vitamin K, and horse blood
Disc Diffusion
Dilute antibiotics, immerse filter paper and cut to size, place discs on a plate swabbed with bacteria, incubate, and measure diameter of inhibition zone
E Test
Make serial dilution of antibiotics, immerse filter paper, cut paper to strips, place strips on a plate swabbed with bacteria, determine last dilution that inhibited growth to determine minimum inhibitory concentration
Agar Dilution
Serially dilute agar with antibiotics and determine the minimum inhibitory concentration
Minimum Inhibitory Concentration
Last concentration that inhibited bacterial growth
Macrodilution
Create serial dilutions of each antimicrobial, inoculate bacteria, determine minimum inhibitory concentration
Microdilution
Create serial dilutions in micro plate, inoculate and incubate, determine minimum inhibitory concentration
Quality Control
Include genetically stable known reference bacteria strains, results should match set standards
Control spreading AMR
Surveillance, educate, find alternatives