16 Questions
What is the primary function of the peptidoglycan in bacterial cell walls?
To maintain the normal shape and protect against extracellular injury
What is the effect of β-lactam antibiotics on susceptible bacterial cells?
They inhibit the biosynthesis of cell walls, causing cell death
How do β-lactam antibiotics interact with PBPs?
They inhibit PBPs, preventing cell wall biosynthesis
What is the result of β-lactamase activity on β-lactam antibiotics?
The antibiotics are hydrolyzed, producing a product with little to no antimicrobial activity
What is the role of the autolysome in Gram positive bacteria?
It concentrates between the plasma membrane and the bacterial wall, leading to cell lysis
What is the primary mechanism of resistance to β-lactam antibiotics in bacterial cells?
Production of broad-spectrum β-lactamases
What is the fate of the old cell wall material during cell division?
It is spun off and discarded
What is the common mode of action of PBPs?
They share the same molecular mode of action, but are not directly involved in cell wall biosynthesis
What is the main source of β-lactam antibiotic resistance in bacteria?
Production of β-lactamases
How do mutated versions of PBP affect β-lactam antibiotics?
They reduce affinity
What type of bacteria can have cell wall ultrastructures resembling Streptococcus pneumonia?
Gram-positive bacteria
Which bacteria are mainly targeted by cell wall synthesis inhibiting antibiotics that do not lyse them?
Methicillin-resistant Staphylococcus aureus
Among the β-lactam antibiotics, which class is the most widely used?
Penicillins
What is a fundamental chemical structure of penicillins?
β-lactam nucleus
What has it been more than 90 years since?
First report on penicillin
How do β-lactam antibiotics exert their antimicrobial action?
By inhibiting cell wall biosynthesis
Study Notes
Bactericidal Action of β-Lactam Antibiotics
- The motives behind the bactericidal action of β-lactam antibiotics are not fully understood, but it is hypothesized that the destruction of peptidoglycan synthesis causes the bacteria to kill.
- The lysis in Gram-negative bacteria is hypothesized to be promoted by the digestion of peptidoglycan, leading to the release of muropeptides.
Importance of Peptidoglycan in Bacterial Cells
- Bacterial cells have a rigid cell wall consisting of peptidoglycan, which is essential for survival and provides protection against extracellular injury and maintains their normal shape.
- The absence of a cell wall makes bacterial cells osmotically fragile and prone to taking up excessive water, leading to their death.
Mode of Action of β-Lactam Antibiotics
- β-Lactam antibiotics interrupt the biosynthesis of cell walls in susceptible cells by inhibiting penicillin-binding proteins (PBPs).
- During cell division, most PBPs are engaged in cell wall biosynthesis and spin off the old cell wall material, making them a target for β-lactam antibiotics.
Resistance to β-Lactam Antibiotics
- Bacterial cells can acquire resistance to β-lactam antibiotics by producing broad-spectrum β-lactamases (penicillinases) that can hydrolyze the amide bond in the β-lactam ring.
- The production of β-lactamases is an important source of resistance in Gram-negative and some Gram-positive bacteria.
- Mutated versions of PBPs can reduce the affinity for β-lactam antibiotics, contributing to resistance.
Types of β-Lactam Antibiotics
- β-Lactam antibiotics are the most widely used class of antibiotics, with different agents including penicillins, cephalosporins, monobactams, and carbapenems.
- Penicillins are the most dominant type of β-lactam antibiotic, containing the β-lactam nucleus as its fundamental chemical structure.
Characteristics of Penicillins
- Penicillins are susceptible to β-lactamases, leading to the rapid development of resistance.
- Despite being discovered over 90 years ago, penicillins are still believed to have potential for developing modern and highly potent antibiotics.
This quiz explores the hypothesized mechanisms behind the bactericidal action of certain agents, including the destruction of peptidoglycan synthesis and the lysis of gram-negative bacteria.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
