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Antimicrobials and Antimicrobial Resistance - Coggle Diagram
Antimicrobials and Antimicrobial Resistance
Antimicrobials
Penicillin
Effective in killing bacterial species
Different chemical groups attached to an amino group
Modifications alter stability
Selective toxicity
Cause greater harm to microbes than patient
Therapeutic index: lowest dose toxic to patient
High TI: less toxic and low TI: blood monitored for toxicity
Antimicrobial action
Static inhibits microbial growth
Cidal kil microbes
Spectrum
Broad-spectrum affect wide range of microbes
Disrupt normal microbiota
Narrow spectrum affect limited range of microbes
Less disruptive to normal microbiota
Combinations
Antagonistic: drugs interfere with each other
Synergistic: One drug enhances other
Additive: Neither
Adverse effects
Toxic effects
Allergic reactions
Suppression of normal microbiota
Susceptibility
MIC: lowest concentration that prevents growth in vitro
Growth rate via turbidity to interpret results
E test uses strip with gradient of drug
Intersection of zone of inhibition indicates MIC
MBC: lowest concentration that kills 9.99% of cells in vitro
Zone of inhibition compared with specially prepared charts
Strain is susceptible, intermediate or resistant
Size of zone depends on concentration of microbes
B-Lactam Drugs
Pencillin
Natural
Act against Gram positive and a few gram negative
Penicillin chrysogenum
Penicillinase-resistant
Methicillin, dicloxacillin
Produce altered cell wall synthesis enzymes to which B-lactam drugs do no bind
Broad spectrum
Ampicillin, amoxicillin
Act against Gram positive/negative due to side chain
Extended spectrum
Ticarcillin, pipperacillin
Reduced activity against gram positive
Destroyed by many B-lactamases
Penillins + B-lactamase inhibitor
Inhibitor to protect penicillin
Amoxicillin, clavulanic acid
Disrupt peptidoglycan synthesis
All have B-Lactam ring
Effective against actively growing cells
Chephalosporins
Resistant to certain B-lactamases
Low affinity for PBPs of gram positives
Carbapenems and monobactams
Resist B-lactamases
Cell wall inhibitors
Vancomycin
Blocks peptidoglycan synthesis
Binds to wall peptides to prevent them from being put into the cell wall
Poorly absorbed by intestinal tract
Does not cross outer membrane of gram-negative
Resistance is a problem
Change in wall peptide prevents binding
Resistance
Mechanisms
Destroy drug
Change target so it doesn't bind the drug
Keep the drug and the target away from each other
Stop growing or grow slowly
Intrinsic
Naturally resistant to certain antibiotics
Gram negatives reduce permeability to molecules much larger
Acquisition
Spontaneous mutations
Low rate but significant
Replicatioon
Combination therapy
Gene transfer
Conjugative transfer of R plasmids
Can spread to different strains, species and genera
Examples
Enterococci
Staphylococcus aureus
Streptococcus Pneumoniae
Enterobacteriaceae
Mycobacterium tuberculosis
Slow emergence and resistance
Cooperation from everyone globally
Responsibilities of healthcare workers
Responsibilities of patients
Educated public