Podcast
Questions and Answers
Which class of β-lactamase is located on a conjugated plasmid?
Which class of β-lactamase is located on a conjugated plasmid?
Which enzyme is overproduced by about 85% of MRSA?
Which enzyme is overproduced by about 85% of MRSA?
Which β-lactamase-producing bacteria have a low molecular weight and a wide spectrum of activity?
Which β-lactamase-producing bacteria have a low molecular weight and a wide spectrum of activity?
Which type of β-lactamase requires penicillin to induce enzyme production?
Which type of β-lactamase requires penicillin to induce enzyme production?
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Why is methicillin resistance not related to β-lactamase production?
Why is methicillin resistance not related to β-lactamase production?
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Which cephalosporin is temporarily resistant to enzyme degradation by Staphylococcus aureus β-lactamases?
Which cephalosporin is temporarily resistant to enzyme degradation by Staphylococcus aureus β-lactamases?
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What is the primary mechanism of resistance to β-lactam antibiotics in bacteria?
What is the primary mechanism of resistance to β-lactam antibiotics in bacteria?
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Which bacterial species is part of the group that produces constitutive β-lactamase?
Which bacterial species is part of the group that produces constitutive β-lactamase?
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Study Notes
β-Lactamase Resistance
- Exposure to low doses of antibiotics selects for bacteria to produce β-lactamase resistance.
- There are four classes of β-lactamase produced by organisms: class A, class B, class C, and class D.
Regulation of β-Lactamase
- Class A, C, and D β-lactamase are regulated by chromosomal genes and are induced by penicillin and cephalosporin.
- Class B β-lactamase is located on a conjugated plasmid and does not require induction by penicillin or cephalosporin.
Characteristics of β-Lactamases
- β-Lactamases of Staphylococcus aureus have a low molecular weight and a wide spectrum of activity.
- They have high efficiency in destroying penicillin group and most first- and second-generation cephalosporins.
Methicillin Resistance
- Methicillin resistance is not related to β-lactamase production since methicillin does not have a β-lactam ring structure.
- About 85% of MRSA (Methicillin-resistant Staphylococcus aureus) overproduce penicillin binding protein PBP 2a and PBP 2’.
Mechanism of Resistance
- Production of β-lactamase is the principal mechanism of resistance to β-lactam antibiotics in bacteria.
- β-Lactamase leads to hydrolysis of penicillin, rendering it ineffective.
Types of β-Lactamase
- Two types of β-lactamase: inducible (e.g., E. coli) and constitutive (e.g., Staphylococci, Streptococci, Neisseria, and Clostridium species).
- Constitutive β-lactamase is very effective against penicillin, but its activity against methicillin, cephalosporin, imipenem, and oferaroxamin is variable.
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Description
Learn about the different classes of β-lactamase produced by bacteria and how they respond to antibiotics. Understand the regulation of these genes and their chromosomal location.
