Antimicrobial Resistance Flashcards
What are the three major purposes of antimicrobial prescription?
Therapeutic: If an individual is sick, treat patient to cure.
Metaphylactics: If one patient is noticed in a heard, treat the whole heard to prevent spread.
Prophylactic: Seasonal prescription of drug to prevent the most susceptible population within a heard.
What is contributing to antimicrobial resistance/ overuse?
Metaphylactics: If one patient is noticed in a heard, treat the whole heard to prevent spread.
Prophylactic: Seasonal prescription of drug to prevent the most susceptible population within a heard.
- Antimicrobial overuse in intensive farms (pigs & poultry), dry cow therapy, and shipping of animals
What is the main starting cause of Antimicrobial resistance?
Unregulated use of antimicrobials in
animal or humans to AMR bacteria
What is the trend of spread of antimicrobial resistance?
Unregulated antimicrobial use -> Use of feces/ water contained with AMR bacteria as fertilizer-> food containing AMR bacteria from feces -> AMR bacteria spread to public via food and water
What is the current morbidity and mortality due to antimicrobial resistance cases?
Morbidity : 2 million people in the US
Mortality: 1-27 million people globally
What is the projected morbidity and global economic cost due to antimicrobial resistance cases in 2050?
Morbidity : 10 million people in the US annually
Economic cost: 100 trillion
What are the mode of bacterial growth?
Plankton life stage finds a place to attach, and begins immobile/ sessile growth. Its biofilm matures and at a certain point it will begin to disperse.
What are the 5 major groups of bacteria? What are they classified by?
Bacteria are classified into 5 major groups by their cell wall architecture
- Classic Gram +
- Mycobacterium
- Classic Gram -
- Chlamydia
- Mycoplasma
What is a classic gram positive bacteria cell wall architecture?
- several layers ( tiers of peptidoglycan with lipo/teichoic acid.
What is the cell wall architecture of a mycobacterium?
peptidoglycan is covered by mycolic acid (wax or lipids)
What is the cell wall architecture of a classic gram negative bacteria?
Outer membrane (OM) made up of protiens & lipopolysaccharide ( lipid A & sugar or endotoxin)
What is the cell wall architecture of Chlamydia bacteria?
cell wall without peptidoglycan. Outermembrane with protiens and lipopolysaccharide ( lipid A + sugar or endotoxin)
What is the cell wall architecture of mycoplasma bacteria?
Mycoplasma has no cell wall
has sterols in cell membrane
Is mycoplasma stained by gram stain?
NO
If you have an antimicrobial that acts by inhibiting cell wall, which major group of bacteria will be resistant?
Mycoplasma
What are the steps to gram staining bacterial slides?
- ) Fix bacteria to slide using flame 2-3 x
- ) Add crystal violet and aggitate for 60 seconds
- ) Add iodine and aggitate for 60 seconds
- ) Decolorize slide with (alcohol) for 15 seconds
- ) Stain with Safranin for 60 seconds.
What does each letter indicate on this image of a bacteria?
A.) Capsule
B.) Porins
C.) Pili
What are biofilms?
Dense bacteria community
What are the 6 mechanisms of action of microbials?
Cell wall synthesis
Metabolism – folic acid synthesis
30S – protein synthesis
50S – protein synthesis
RNA polymerase – mRNA (RNA synthesis)
DNA gyrase/topoisomerase
(DNA synthesis)
Which antibiotics interfere with bacterial cell wall synthesis?
β-lactams
Penicillins
Cephalosporins
Carbapenems
Monobactams
mnemonic: Bitter People Can Carry Misery
Which antibiotics interfere with bacterial metabolism/ folic acid synthesis?
Sulfonamides Trimethoprim
Mnemic Second Trimester
Which antibiotics interfere with 30 S bacterial protein synthesis?
Tetracyclines
Aminoglycosides
mnemonic: 30S Alarm Tone
Which antibiotics interfere with 50 S bacterial protein synthesis?
Mycolides
Chloroamphenicol
mnemonics: 50$ Cash Money
Which antibiotics interfere with RNA polymerase - RNA synthesis?
Rifamycins
Which antibiotics interfere with DNA gyrase/topoisomerase (DNA synthesis)?
Flouroquinolones
Nitroimidazoles
mnemonic: DNA’s For Nerds
What are the 4 major new AMR mechanisms?
- ) Reduced permeability
- ) Efflux Pumping (vomiting)
- ) Drug inactivation by enzymes
- ) Target site change, modification or protection.
How does Biofilm formation also affect AMR?
- ) Induced extracellular polymer (matrix) production as a barrier
- ) Thick impenetrable communities as a barrier
- ) Low nutrient & oxygen supply to the center
- ) Dormant spore-like cell in the center for persistence
Limit uptake due to low permeability
What antibiotics are less efficient due to the following AMR mechanism: Mutation on the porin channel to reduce membrane permeability & limit entry of the drug into cytoplasm
Amonoglycosides
Quinolones
beta-lactam
Chloramphenicol
Rifamycin
Tetracycline
What antibiotics are less efficient due to the following AMR mechanism: Acquire efflux transporter genes or increase their expression for pumping out the drug from the cytoplasm
Tetracycline
What antibiotics are less efficient due to the following AMR mechanism: Change the drug target sites by modification, mutation, capping or protection of binding-site
Amonoglycosides
Tetracycline
Rifamycin
Quinolones
beta-lactams
What antibiotics are less efficient due to the following AMR mechanism: Expression of potent enzymes that destroy or enzymatically modify the drug (mainily encoded by plasmid)
beta-lactams
Amonoglycosides
What is the major AMR mechanism that inhibits Beta lactams and amonoglycosides?
Expression of potent enzymes that destroy or enzymatically modify the drug (mainily encoded by plasmid)
What is the major AMR mechanism that inhibits Chloramphenicol Microlids?
Change the drug target sites by modification, mutation, capping or protection of binding-site
What is the major AMR mechanism that inhibits Quinolones?
Change the drug target sites by modification, mutation, capping or protection of binding-site
What is the major AMR mechanism that inhibits Rifamycin?
Change the drug target sites by modification, mutation, capping or protection of binding-site
What is the major AMR mechanism that inhibits tetracycline?
Acquire efflux transporter genes or increase their expression for pumping out the drug from the cytoplasm
What antimicrobial resistance mechanism is used against betalactams in gram negative bacteria?
Gram negative (uptake ESBL &/or carba plasmids): beta-lactamase enzyme production
What antimicrobial resistance mechanism is used against betalactams in gram positive bacteria?
Gram positive (uptake SCC) : Change in binding site of beta-lactams (mutation of peptidase /PBP)
What are the ESBL enzymes that destroy beta lactam antimicrobials that are transmitted by plasmids?
TEM = named for patient Temoneira
SHV = sulfhydryl variant enzyme
CTX-M = cefotaximase
What are the carbapebenase enzymes that destroy beta lactam antimicrobials that are transmitted by plasmids?
KPC (Klebsiella pneumoniae carbapenemase)
IMP (Imipenemase metallo-beta-lactamase)
NDM (New Delhi metallo-beta-lactamase)
VIM (Verona integron-encoded metallo-beta-L)
OXA (Oxacillin carbapenemases)
What caused the origin of AMR?
- Acquired resistance- > horizontal gene transfer -> 1.) Dna in nature (transformation). 2.) Plasmid (conjugation) 3.) Bacteriophage (transduction)
- Intrinsic (innate/ natual resistance -> Vertical gene transfer
What antimicrobials do not work on mycoplasma and why?
These bacteria are resistant to antimicrobials that act on the cell wall. These are examples of those bacteria:
Penicillin
Cephalosporin
Carbapenem
Monobactum
What are the 3 sets of guidelines for AMR detection that we should follow if needed?
Clinical & Laboratory Standards Institute (CLSI), USA
European Committee on Antimicrobial Susceptibility Testing (EUCAST) or
International Standardization Organization (ISO)
What are examples of enterobacteriaceae targeted for AMR testing?
- E.coli
- Salmonella
- Klebseilla
- Citrobacter
- Enterobacter
- Proteus
What are examples of other gram negative bacilli targeted for AMR testing?
Acinetobacter
Pseudomonas
What are examples of non fastidious gram positives targeted for AMR testing?
Staphylococcus
What are examples of fastidious organisms targeted for AMR testing?
Streptococci
Campylobacter,
Erysipelothrix,
Listeria,
Hemophilus,
Neisseria,
Helicobacter
What are examples of Bioterrorism agents targeted for AMR testing?
B. anthracis,
Yersinia pests,
Brucella,
Franci sella tularensis
Burkholderia mallei
peudomallei
What are examples of anerobic microbes targeted for AMR testing?
Fusobacterium
Clostridium,
Bacteroides,
What are the 6 bacteria species termed as ESKAPE which are famous in AMR globally?
Enterococcus
S. aureus
K. pneumoniae
A. baumannii
P. aeruginosa
Enterobacter
What bacteria is cultured on mannitol salt agar?
Staphylococcus,
Enterococcus,
Listeria
Micrococcaceae
What bacteria is cultured on edward media?
Streptococcus
Enterococcus
What bacteria is cultured on kenner-fecal agar media?
Enterococcus (selective media)
What bacteria is cultured on MacConkey agar?
Enterobacteriaceae
Enterococcus
What is the type of broth media used for Aerobic bacteria to screen isolates for AMR?
Cation-adjusted Mueller-Hinton broth
What is the type of agar media used for Aerobic bacteria to screen isolates for AMR?
Cation-adjusted Mueller-Hinton agar
What is the type of broth media used for Anaerobic bacteria to screen isolates for AMR?
Brucella broth + (5µg/ml hemin, µg/ml vitamin K and 5% lysed horse blood)
What is the type of agar media used for Anaerobic bacteria to screen isolates for AMR?
Brucella agar +3-5% lysed horse blood
What is disc diffusion? Is it a qualatative or quantitative method?
This is when bacterial cultures are grown on an agar disc, but discs of various antibiotics are placed to determine the sensitivities to specific antibiotics by the grown culture. This is a qualatative method
What is an E test? Is it a qualatative or quantitative method?
Culture is grown on a plate and strip impregnated with a drug is placed on a solid media. the strip has decreasing quantities of drug placed as you move towards the center so this will show the minimum inhibitory concentration. This is quantitative method.
What test type is seen in this image?
E test
What test is seen in this image?
Disc diffusion
What is agar dilution? Is this Quantitative or Qualitative? What will this method give you in terms of results
Agar dilution involves the incorporation of different concentrations of the antimicrobial substance into an agar medium followed by the application of a standardized number of cells to the surface of the agar plate.
Quantitative method
MIC: Minimum inhibitory concentration
What is macrodilution? Is it quantitative or qualatative?
After a culture is done, the colonies are placed in rich media broth and left overnight. The colonies are then added equally to a series of dilutions of antimicrobials. You also will plate your control sample to make sure bacteria is still viable. All of these samples will be left overnight. The next day you will see the MIC is the tube that is the lowest without bacterial growth.
What would the MIC be in this example of macrodilution?
8 ug/ml
What test is seen here?
microdilution
What is a microdilution?
(1) first prepare 2-fold serial dilutions of the test compounds (up to 7) and one quality control (QC) antibiotic in a microdilution plate.
(2) Create the inoculum by taking a few colonies from an agar plate with a sterile swab, preparing a McFarland standard, and diluting the McFarland standard into media.
(3) Dispense the inoculum into the microdilution plate with the serial diluted test compounds and incubate the microdilution plate.
(4) Read the microdilution plate to determine the MIC value.
(5) Plate a portion of each well on an appropriate agar media, incubate the agar, and check for colonies to determine the MBC.
What are the quality controls used for a survey on beta lactamases producing bacteria?
E.coli ATCC 35218
Klebsiella pneumoniae ATCC 700603
Klebsiella pneumoniae ATCC BAA-1705 or BAA-2814
Acinectobacter baumannii NCTC 13304
What are the quality controls used for a survey on non- fastidious bacteria for agar/ broth dilution?
E.coli ATCC 25922
Pseudomona aeruginosa ATCC 27853
Enterobacter faecalis ATCC 259212
Staphylococcus aureus ATCC 29213
What are the quality controls used for a survey bacteria of bioterrorism?
E.coli ATCC 25922
Staphylococcus aureus ATCC 29213
When would you invalidate a test after using known reference bacterial strains?
Invalidate the test if:
- there is no viable & pure growth of the quality control strains
or
- their cut-off value inhibition zone by disk or MIC is not within the range defined by CLSI, EUCAST or ISO
What is the list of 11 antimicrobial classes ?
- )Aminoglycosides. e.g. Amikacin, Gentamycin, Kanamycin, Neomycin, Streptomycin
- ) Carbapenem. e.g. Ertapenem, Imipenem, Meropenem
- ) Cephalosporins (G1-G5). e.g. Cephalothin, Cefoxitin, Cefotaxime, Ceftazidine, Ceftiofur, Cefepime, Ceftaroline.
- ) Chloramphenicol. e.g. Florfenicol
- ) Lincosamide e.g. Pirlimycin.
- ) Microlides. e.g. Erythromycin, Spiramycin.
- ) Penicillins. e.g. Ampicillin,Amoxicillin, Methicillin, Oxacilli.
- ) Polypeptides. e.g. Polymyxin B, Bactracin, Colistin.
- ) Quinolones (G1-G4). e.g. Nalidixic acid, Ciprofloxacin, Norfloxacin, Moxifloxacin
- ) Sulfonamides. e.g. Sulfadimethoxine, Trimethoprim-sulfamethoxazone.
- ) Tetracycline: e.g. Oxytetracycline
Any Cat Could Carry Large Mice Probably. Physiologic Quickness Stops Them. ( IDK what else to make, keep thinking ***
What is a general rule when setting up an agar/ broth dilution?
General rule: 1. The agar/broth dilution should include the drug concentration levels below the susceptible & above the resistant breakpoints of the CLSI guidelines.
Test against few number of antimicrobials that you use in your state or
farm/clinic because you cannot do the AMR testing for all of the antimicrobials on the market
Waht is the MIC Cut off values for most antimicrobials?
E.g. MIC cut-off values of most antimicrobials ranges between
0.5 to 64 μg/ml
What test is not reccomended fo anerobic bacterial cultures?
Disc Diffusion
What media should be used on anerobic bacteria? (Actinomyces, Bacteroides, Clostridium, Fusobacterium)
Use Brucella agar or broth media
What media is ideal for fastidious aerobic bacteria? (Campylobacter, Erysipelothrix, Haemophilus, Helicobacter, Listeria, Neisseria, Pasteurella, and Streptococcus)
Cation-adjusted Mueller-Hinton broth or agar
Disc diffusion or E test
What media is ideal nonfastidious fast growing aerobic bacteria in 16-20h? (Staphylococcus, Entrobacteriaceae, pseudomona)
Cation-adjusted Mueller-Hinton broth or agar
Disc diffusion or E test
How can you control the fast spreading AMR on farms, national and worldwide?
- Survaillence
- Education
- Alternatives to antimicrobials
What is the benefits of surveillance of AMR? (i.e periodic survey to measure in the population, food, feed, water, etc.)
- Survey on drug use pattern and prioritize the different drugs for use
- Develop and use faster diagnostic testing of AMR
- Survey regularly antimicrobial resistance patterns in pathogens
What are the benefits of education of AMR?
Educate expertise for reducing drug use in animals & regulate, monitor and evaluate if the drug use is as per the set priority
- Therapeutic use (only treat the sick individuals with required dose, duration and frequency)
- Educate against Metaphylactic use and inform of harm caused. (if one sick individual is observed, treat the whole herd/flock policy)
- Advise against : Prophylactic use (blanket seasonal use even if there is no sick animal)
What are the ways we can find alternatives to antimicrobials for animals?
- Improved animal hubandry and nutrition ( less stress, immune system can function better)
- Use vaccines and invest on new vaccine development
- New antimicrobial discoverys
- Phage therapy
What 4 main mechanisms do bacteria use for AMR?
porin, binding site, enzyme, and pumping
Where can bacteria aquire AMR genes from?
Bacteria can acquire AMR genes from at least 4 sources: plasmid, phage, free DNA, & parents
What are the 5 culture based assays that can be used to test isolates for AMR?
- Testing of isolates for AMR can be done by 5 culture based assays: Disc diffusion, E-test, agar dilution, macrodilution, and microdilution
- PCR, whole genome sequencing, serology can also be used to detect AMR
What are 6 broad interventions that can control AMR?
AMR may be controlled by 6 broad interventions: judicious drug use, surveillance, diagnosis, discoveries, collaborations, & policy/practice change
