Chapter 1: L3 Flashcards
(39 cards)
refers to the ability of microorganisms—such as bacteria, fungi, viruses, and parasites—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
Antimicrobial Resistance (AMR)
Causes of Antimicrobial Resistance (6)
- Overuse of Antibiotics
- Incomplete Courses of Treatment
- Self-medication:
- Poor Infection Control:
- Environmental Contamination
- Genetic Mutations
Mechanisms Develop by Microorganisms
to become Resistant (6)
- Enzyme Production (Degradation or Modification of Antibiotics)
- Efflux Pumps
- Alteration of Target Sites
- Reduced Permeability (Decreased Antibiotic Uptake)
5.Biofilm Formation - Horizontal Gene Transfer (HGT)
some bacteria produce enzymes that degrade or chemically
modify the antibiotics, rendering them ineffective.- These enzymes can break down the molecular structure of the
antibiotic before it can act on the bacteria
Enzyme
Production (Degradation or
Modification of Antibiotics)
examples of Enzyme
Production (Degradation or
Modification of Antibiotics)
β-lactamase Enzymes (Extended-Spectrum Beta-Lactamases (ESBLs));
Carbapenemases:
: These enzymes degrade antibiotics
(e.g., penicillins, cephalosporins) by breaking the ___ ring that is
critical for the antibiotic’s function.
β-lactamase Enzymes; β-lactam
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:
are protein complexes found in the
bacterial cell membrane that actively expel harmful substances, including antibiotics, from inside the bacterial cell
Efflux pumps
This reduces the intracellular concentration of the antibiotic to sub-lethal levels, allowing the bacteria to
survive
Efflux pumps
examples of efflux pumps
AcrAB-TolC Efflux Pump in E. coli
MexAB-OprM Efflux Pump in Pseudomonas aeruginosa
This system is
responsible for expelling a variety of antibiotics,
including tetracycline, fluoroquinolones, and β-lactams.
AcrAB-TolC Efflux Pump in E. coli:
This pump is involved in the resistance to antibiotics like
ciprofloxacin.
MexAB-OprM Efflux Pump in Pseudomonas aeruginosa:
Bacteria can modify the molecular structures of the target sites
where antibiotics normally bind and exert their effects.–
These structural changes prevent the antibiotic from
recognizing or binding to its target, neutralizing its action
Alteration
of Target Sites
examples of Alteration of Target Site
-Penicillin-Binding Proteins (PBPs):
Methicillin-Resistant Staphylococcus aureus (MRSA)
-Modification of Ribosomal Targets:
Resistance to Macrolides (e.g., Erythromycin):
-Target Enzyme Modifications:
Fluoroquinolone Resistance
have altered PBPs that prevent
methicillin and other β-lactam antibiotics from
binding to the bacterial cell wall.
MRSA bacteria
: Bacteria can modify the ribosomal binding sites, making it impossible for macrolide antibiotics to bind and inhibit protein synthesis.
Resistance to Macrolides (e.g., Erythromycin)
In some bacteria, mutations in the
gyrase or topoisomerase enzymes make the antibiotic less effective.
Fluoroquinolone
Resistance:
Some bacteria alter the permeability of their cell membranes,
making it more difficult for antibiotics to enter the cell.
This can occur through mutations in membrane porins (protein
channels that allow substances to pass through the membrane).
Reduced
Permeability (Decreased
Antibiotic Uptake)
Reduced
Permeability (Decreased
Antibiotic Uptake) examples
Pseudomonas aeruginosa Resistance to Penicillins:
Neisseria gonorrhoeae
In ___, the bacteria can reduce the
number of porins in their outer membrane, making it harder
for penicillins (and other antibiotics) to penetrate
Pseudomonas aeruginosa
certain strains of ____ can reduce the expression of porins, thus decreasing the uptake of
antibiotics like penicillin
Neisseria gonorrhoeae
Manybacteria can form ___, which are clusters of bacterial cells
embedded in a self-produced matrix of ___.
biofilms;
extracellular polymeric
substances (EPS)
