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Antibiotic Resistance - Coggle Diagram
Antibiotic Resistance
Antibiotics
Cell wall inhibition
- Beta-lactams (penicillins, cefalosporins, carbapenems and monobactams)
- Glycopeptides (vancomycin and teicoplanin)
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Causes of resistance
Agriculture, aquaculture and farming animals contribute to resistance.
- Poultry - high prevelance of MRSA
- Salmon - given antibiotics and antifungals
- We consume these products and essential recieve a low dose of antibiotic which develops resistance.
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Close contacts in less hygienic environments,
- Cheap accommodation
- Indigenious communities
- Refugee camps
Resistance
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Mechanism of resistance
Antibiotic inactivation: most common resistance (in beta lactams for example)
- Enzymes secreted to destory the beta-lactam bond deactivating antibiotic.
- Produced by both gram-negative and positive bacteria
- Less effective of diclox/flucloxacillin and cefalosporins
- Some bacteria (ESCAPPAM) can produce inducible beta-lactam enzymes and treatment with cephalosporins can cause organisms to produce beta-lactamase enzyme.
- Problems are suspectibility with show that cephalosporins are effective against ESCAPPAM but infections my not resolve.
- May require more broader-sepctum agents wtih 2 MOA + higher doses for treatment
Alteration in binding sites/target: Changed binding site = less binding = less effective.
- Example: betalactams bind to penicillin binding proteins. Damage or changes to the protein = antibiotic will not bind and not be effective.
- Altered ribosome targets: 30s and 50s subunit resistance
- Altered DNA-gyrase binding site: quinolones will become ineffective in stopping genetic replication
Decreased permeability of antibiotic into cell wall: Gram-negtaive bacteria have a complex cell wall and antibiotics rely on porins to enter.
- Changes to the porins will reduce or stop antibiotic from entering cell.
Active antibiotic reflux: Bacteria actively pump antibiotic out
- Tetracyclines (doxycycline) and fluoroquinolones (ciprofloxacin) are affected
Staph Aureus Resistance
- Methicllin sensitive S. Aureus (MSSA)
- Methicllin resistant S. Aureus (MRSA)
- Hosptial MRSA and Community MRSA
Treatment
- MSSA: Flu/dicloxacillin 500mg oral - 2g IV q4-6 hrly
- CA-MRSA: Clindamycin 450mg oral/IV q8 hrly OR sulfamethoxazole/trimethoprim 800/1600mg oral 12 hrly
- HA-MRSA: Vancomycin or Rifampicin 300mg 12 hrlys + folic acid 500mg 12 hrly
Alternative treatment for MRSA:
- Daptomycin 4-6mg/kg IV daily
- Telavacin 10mg/kg IV daily
- Ceftraoline 600mg IV 12hrly
- Linezolid 600mg oral/IV 12 hrly
Classification
More bacteria exposed to antibiotic, both appropriate and inappropriate the more defences they develop
Counterfeit antibiotics
- Most counterfeited medicine (improper doses, mixed with other chemicals)
- Patient uses counterfeit thinking infection is treated
- Bacteria exposed to low levels of antibiotic and resistance develops - harder to treat.