Antimicrobial resistance Flashcards
What is antimicrobial resistance
when bacteria, viruses, fungi and parasites no longer respond to antimicrobial medicines
What factor is the reason for some antibiotics exhibiting narrow spectrum activity and some exhibiting broad spectrum activity
depdent upon whether the target of the antibiotic is present in only certain types of bacteria or if it is present in all
List some examples of antimicrobial targets in bacteria
cell wall synthesis
folic acid metabolism
DNA gyrase
protein synthesis - 50s inhibitors and 30S inhibitors
lipid biosynthesis
What is a bacteria static agent
inhibits important biological processes such as protein synthesis
weak target binding
if the agent is removed, cell continues growing
What is a bactericidal agent
kills the cell and has strong target binding
cell is not lysed so total cell count remains constant, but viable cell count (live bacteria) decreases
What is a bacteriolytic agent
kill and lyses the cell so cytoplasmic contents such as detergents are released as the cytoplasmic membrane is ruptured
cell is lysed so both the total and viable cell count will decrease
How do cell wall inhibitors that include a beta lactam ring work?
the beta lactam ring interferes with transpeptidation (a reaction which results in the cross-linking of 2 glycan-linked peptide genes, leading to peptidoglycan synthesis)
results in cell wall synthesis being blocked - unstable cell wall leads to bacterial death
How do nucleic acid synthesis inhibitors work> such as quinolones?
disrupted bacterial metabolism by interfering with bacterial DNA gyrase. prevents DNA supercoiling which is needed to package DNA in bacterial cells
What activity do fluoroquinolones exhibit when DNA gyrase is inhibited compared to when DNA is fragmented
DNA gyrase inhibited = bacteriostatic activity
DNA fragmented = bactericidal activity
How to protein synthesis inhibitors work? what are the 3 categories and how do they differ?
inhibit protein translation via ribosomes
aminoglycosides = bind to 30S subunit an cause ribosome to misread mRNA causing error-filled proteins
tetracyclines = similar mode of action to aminoglycosides
macrolides = bind to 50S ribosomal subunit causing partial inhibition of protein synthesis and causing an imbalance in the proteome
What is the resistome and the intrinsic resistome ?
the resistome is a collection of all the antibiotic resistant genes in a given ecosystem
intrinsic resistome = natural way to be AMR
How can AMR be acquired from the intrinsic resistosome?
by HGT or mutations
What are the 3 methods of HGT in bacteria
transformation - uptake of naked DNA by bacteria
transduction - bacterial DNA transferred by viruses
conjugation - direct DNA transfer between bacterial
What is the human microbiome
the entire habitat, including the microorganism, their genomes and the surrounding environmental conditions
How does the maternal microbiota change during pregnancy compared to after pregnancy
during = high diversity of microbiota in colostrum, reduced diversity of gut and vaginal microbiota
after = breast milk microbiota diversity reduced, vaginal microbiota diversity increased
What are some methods of microbiome-based therapies?
probiotics, prebiotics and faecal micobiota transplant
Why may humans be a bad experimental way to study the microbiome?
a ‘healthy’ microbiome is specific to the individual
ethical considerations as diet may be altered and procedures may be invasive
need to consider factors like previous exposure to antibiotics
high level of withdrawal
correlation does not equal causation
What are some culture dependent techniques to study the microbiome
using in vitro model systems
using culturomics
What are some culture independent techniques to study the microbiome
SSU rRNA
metatranscriptomics
meta-proteomics
meta-bonomics
meta-genomics
PCR based using specific primers targeted at AMR genes
