CH 1.3 Antimicrobial Resistance Flashcards
refers to the ability of microorganisms to evolve and develop resistance to the drugs that were once effective at killing or inhibiting them
Antimicrobial Resistance (AMR)
process makes infections harder to treat,
leading to longer illness durations, increased
medical costs, and higher mortality rates
(Degradation or Modification of Antibiotics)
Enzyme Production
(Decreased Antibiotic Uptake)
Reduced Permeability
some bacteria produce enzymes that degrade or chemically
modify the antibiotics, rendering them ineffective.
Enzyme Production
These enzymes can break down the molecular structure of the
antibiotic before it can act on the bacteria.
Enzyme Production
degrade β-lactam antibiotics (e.g., penicillins, cephalosporins) by breaking the β-lactam ring that is
critical for the antibiotic’s function
β-lactamase Enzymes
These are a more
advanced form of β-lactamase enzymes that degrade a broader
range of antibiotics.
Extended-Spectrum Beta-Lactamases (ESBLs)
These enzymes degrade carbapenems, which
are typically used as last-resort antibiotics
Carbapenemases
protein complexes found in the
bacterial cell membrane that actively expel harmful
substances, including antibiotics, from inside the
bacterial cell.
Efflux pumps
Efflux Pump in E. coli
AcrAB-TolC
AcrAB-TolC Efflux Pump is
responsible for expelling a variety of antibiotics, including (3)
tetracycline, fluoroquinolones, and β-lactams.
Efflux Pump in Pseudomonas aeruginosa
MexAB-OprM
MexAB-OprM Efflux Pump is involved in the resistance to antibiotics like
ciprofloxacin
what bacteria altered PBPs that prevent
methicillin and other β-lactam antibiotics from binding to the bacterial cell wall.
Methicillin-Resistant Staphylococcus aureus (MRSA)
Resistanceto Macrolides
Ex.
Erythromycin
Bacteria can
modify the ribosomal binding sites, making it impossible for
macrolide antibiotics to bind and inhibit protein synthesis.
Resistance
to Macrolides
In some bacteria, mutations in the
gyrase or topoisomerase enzymes (which are targeted by
fluoroquinolones) make the antibiotic less effective
Fluoroquinolone Resistance
bacteria that can reduce the
number of porins in their outer membrane, making it harder
for penicillins (and other antibiotics) to penetrate
Pseudomonas aeruginosa
can reduce the expression of porins, thus decreasing the uptake of antibiotics like penicillin
Neisseria gonorrhoeae
which are clusters of bacterial cells
embedded in a self-produced matrix of extracellular polymeric
substances (EPS).
biofilms
physical barrier, protecting bacteria from antibiotics,
host immune responses, and environmental stresses
Biofilms
protect bacteria from antibiotics by acting as a physical
barrier, reducing drug penetration and preventing effective
concentrations from reaching the bacteria.
Biofilms
forms biofilms on medical devices like
catheters or prosthetics, the bacteria within the biofilm are
much less susceptible to antibiotics.
Staphylococcus aureus
forms biofilms in the lungs of cystic fibrosis patients that make the bacteria resistant to treatment with
antibiotics like ciprofloxacin
Pseudomonas aeruginosa
the process by which bacteria acquire genetic material from other bacteria, even from different species.
Horizontal gene transfer (HGT)
allows for the rapid spread of resistance traits across
bacterial populations, enabling the proliferation of resistant
strains even among different species of bacteria
Horizontal gene transfer (HGT)
Transfer of genetic material through direct cell-to-cell contact,
often via plasmids (small DNA molecules)
Conjugation
Uptake offree DNA from the environment. Somebacteria can incorporate DNA containing resistance genes
into their own genome
Transformation
Transfer of genetic material through bacteriophages (viruses
that infect bacteria).
Transduction
___ ___-producing Escherichia coli
Shiga toxin
