Mechanisms of Microbial Resistance Flashcards
What are the 5 targets of antimicrobial therapy?
- Folate metabolism
- Nucleic acid synthesis
- Protein synthesis
- Cell membrane
- Cell wall synthesis
What are three ways bacteria can acquire genetic material?
- Transformation: Transfer of free DNA of resistant DNA from dead bacteria
- Conjugation: Plasmid transfer from another live bacteria
- Transduction: viral DNA inserted
What are the 5 mechanisms of antimicrobial action?
- Inhibit folate metabolism
- Inhibit DNA synthesis
- Inhibit protein synthesis
- Disrupt cell membrane
- Inhibit cell wall formation
Which drugs inhibit folate metabolism? (2)
Trimethoprim and sulfonamides
Nitrofurantoin
What drugs inhibit DNA synthesis? (2)
Quinolones and metronidazole
What drugs inhibit protein synthesis in bacteria? (5)
- Aminoglycosides
- Tetracyclines
- Macrolides (e.g. Erythromycin and Azithromycin)
- Clindamycin
- Linezolid
What drugs disrupt the bacterial cell membrane? (3)
- polymixins
- colistin
- daptomycin
What drugs inhibit bacterial cell wall synthesis? (4)
- Beta lactams: penicillins, cephalosporins, carbapenems
- Vancomycin
What are the 5 mechanisms of microbial resistance?
- Altered target
- Bypass metabolic pathway
- Antibiotic inactivation
- Decreased influx
- Increased efflux
What is an example the altered target mechanism of resistance? (5)
- penicillin binding protein enzyme
- ribosome subunit
- DNA gyrase/topoisomerase IV
- Peptidoglycan precursor
- DHPS/DHFR enzyme
What is an example of bypassing a metabolic pathway in microbial resistance?
Enterococcus scavenging exogenous folate
What is an example of antibiotic inactivation? (2)
- Beta lactamases
- aminoglycoside modifying enzymes
What is an example of a mechanism of decreased antibiotic influx?
P. aeruginosa has decreased production of OprD (carbapenem channel)
What is an example of increased drug efflux in microbial resistance?
- Multidrug pump: Mex-OPR in P. aeruginosa
- Single drug pumps: tet(tetracyclines), mef(macrolides), NorA(quinolones)
What are two situations where antimicrobial resistance can be generated?
- Mutation selects for bacteria that are resistant against the antibiotic
- Genes can be transferred from a resistant bacteria
