Introduction to Chemotherapy & Cell Wall Inhibitors

Antibiotics modified to be effective against gram-positive and many gram-negative bacteria.

Drugs affecting a wide variety of microbial species.

When the maximum tolerated antibiotic level fails to stop bacterial growth.

Some bacteria naturally resist an antibiotic.

Resistance to antibiotics bacteria develop through mutation or selection.

Immune reactions to antimicrobial drugs or their products.

High antibiotic levels harming host cells.

Hearing damage caused by certain antibiotics (e.g., aminoglycosides).

Increased sensitivity to sunlight due to some antibiotics.

Infections that develop as a result of disrupting the body's normal microbial flora, often triggered by antibiotic use. Opportunistic organisms like fungi or resistant bacteria thrive.

Antimicrobial drugs that target the bacterial cell wall, a structure absent in human cells. This disrupts the bacterial wall's structure leading to cell death.

A polymer found in bacterial cell walls; it's made of glycan chains cross-linked with short peptide chains.

A class of antibiotics that interferes with bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs).

The core structure shared by penicillin and similar antibiotics, crucial for their binding to the bacteria.

The process of cross-linking adjacent peptidoglycan strands in bacterial cell walls, a critical step in building a strong cell wall.

Bacterial enzymes that catalyze the cross-linking of peptidoglycan strands. Penicillins bind to these proteins, inhibiting their function.

The range of different bacteria that a specific antibiotic can effectively kill or inhibit.

Bacteria whose cell walls have a thick layer of peptidoglycan making them more susceptible to penicillins (in the absence of resistance).

Penicillins combined with beta-lactamase inhibitors (like clavulanic acid). This combats bacteria that produce beta-lactamase, a chemical that breaks down penicillin.

These penicillins are resistant to beta-lactamases and are used to treat infections caused by penicillinase-producing Staphylococcus species, like Methicillin-sensitive Staphylococcus aureus (MSSA).

A type of Staphylococcus aureus resistant to most beta-lactam antibiotics, posing a serious medical problem.

Penicillins effective against Pseudomonas aeruginosa, often combined with other drugs for wider-spectrum coverage of infections.

A bacterial mechanism to break down beta-lactam antibiotics like penicillins.

Bacteria reducing the ability of the antibiotic to enter, thereby hindering its effectiveness.

A bacterial mechanism that actively removes antibiotics from inside the cell.

Gram-negative bacteria have an outer lipopolysaccharide membrane that acts as a barrier to water-soluble penicillins.

Gram-negative bacteria have proteins called porins that act as channels in the outer membrane, allowing water-soluble molecules, like some penicillins, to pass through.

Penicillin G is more powerful (5-10 times) than penicillin V against Neisseria spp. and certain anaerobes.

Penicillin V is more stable in acidic environments than Penicillin G, making it suitable for oral use.

Chemically modified penicillins with expanded effectiveness against gram-negative bacteria like Haemophilus influenzae, Escherichia coli, and Proteus mirabilis.

Penicillin G is the preferred treatment for gas gangrene and syphilis.

Penicillin V is the preferred oral choice for less severe infections due to its oral absorption and acid stability.

The range of bacteria a particular antibiotic affects.

Modified penicillin-binding proteins (PBPs) have a reduced affinity for beta-lactam antibiotics, making bacteria resistant to these drugs.

Different β-lactam antibiotics are administered through various routes: intravenous or intramuscular for some, while others are taken orally.

Penicillin V is poorly absorbed from the gut due to the acidic environment. Food further reduces absorption of another penicillin.

Amoxicillin shows good absorption from the gut because it is stable in stomach acid.

Penicillins cross the placenta but may not effectively reach areas like bone or CSF unless inflamed.

Most penicillin metabolism is minimal; however, impaired kidney function can alter its breakdown.

Long-acting penicillin forms (e.g., procaine penicillin G, benzathine penicillin G) are injected to provide a slow release of drug into the bloodstream.

A method of killing bacteria by interfering with their ability to make proteins.

Damaging bacterial cell membranes to stop their functioning.

Stopping the manufacture of the bacterial cell wall, leading to cell death.

Blocking an enzyme crucial to bacterial DNA replication.

Bacteria's production of an enzyme that breaks down penicillin, making it ineffective.

Penicillin G is administered via intramuscular or intravenous routes due to its instability in the stomach.

Hypersensitivity reactions (allergic responses), are the most common adverse effect.

Piperacillin is effective against Pseudomonas aeruginosa.

Methicillin is an example of a penicillin effective against some bacteria resistant to penicillinase.

Used to broaden the spectrum of penicillin, making it effective against bacteria that produce beta-lactamase.

Penicillin is commonly used to treat bacterial infections.

Penicillin is less effective against Gram-negative bacteria due to their outer membrane, which limits drug penetration.

Cephalosporins, another class of antibiotics, should be avoided in patients with a penicillin allergy due to potential cross-reactivity.