Ch. 42: Antimicrobial Sensitivity Testing Flashcards
What is one of the world’s most pressing public and animal health problems?
Antibiotic resistance
What is antibiotic resistance?
When a microbe changes or mutates in some way that reduces or eliminates the effectiveness of drugs, chemicals, or other agents designed to cure or prevent infections
What are antibiotics?
Medicine that inhibit the growth of or destroy microorganisms
_____ can provide codes that allow bacteria to become resistant to antibiotics?
DNA
What are 3 ways bacteria can act antibiotically resistant?
- Neutralize the antibiotic before it can do harm
- Rapidly pump the antibiotic out
- Change the antibiotic attack site so that it can’t affect the function of the bacteria
It is _____ and not animals, that become resistant to drugs.
Microbes
The most common mutation/form of antimicrobial resistance involves what?
Extended-spectrum beta lactamase (ESBL)
What is B-lactamases also known as?
Penicillinase
What are B-lactamases?
Enzymes produced by some bacteria that provide multiresistant to B-lactam antibiotics that break down the antibiotic structure
What are B-lactam antibiotics typically used for?
Treating infections with a broad spectrum of G+ and G- bacteria
What are examples of B-lactam antibiotics?
Penicillins, cephalosporins, and cephamycins
What is the common element in all B-lactam antibiotics?
A four-atom ring known as a B-lactam
How is the bacteria able to break down B-lactam antibiotics?
Through hydrolysis, lactamase produced by the bacteria cleaves the B-lactam ring, deactivating the antibacterial properties of the medication
What bacterial species are examples of ESBLs?
E. coli, Klebsiella, Proteus, and other G- rods
These are often also resistant to aminoglycosides, fluoroquinolones, and other antimicrobials
What are the four ways bacteria can acquire DNA for antibiotic resistance?
- Conjugation
- Tranformation
- Transduction
- Transposition
What way of bacteria acquiring DNA is most common?
Conjucation
Transformation and Transduction typically occur between what bacteria?
Bacteria that are the same or closely-related species
What are plasmids?
Circular DNA sections that replicate independently of chromosomes
Conjucation is encoded by what structures?
Plasmids or transposons
Plasmids is most common
What are transposons?
Mobile sections of DNA that can move between or within genomes
Aka transposable elements or jumping genes
Conjugation requires _____ contact between cells.
Direct
What bacteria have a conjugation pilus (F-pilus or sex pilus) that allow for conjugation?
Gram-negtive
It is not known how Gram-positive are able to do this
What is DNA transformation?
When bacteria take up extra-cellular DNA and incorporate it into their genomes (Usually from lysed cells that release their contents)
What are “competent” bacteria?
Bacteria able to bind large amounts of DNA
