Bacterial Cell Wall Inhibitors & Penicillins

Bacterial Cell Wall Inhibitors

• Bacterial cell wall inhibitors are a class of antibiotics that target the cell wall of bacteria to stop their growth and reproduction.
• β-Lactams share a β-lactam ring in their molecular structure. Penicillins, cephalosporins, monobactams, and carbapenems are examples.
• Non-β-Lactam inhibitors include polypeptides (e.g., bacitracin and cycloserine), glycopeptides (e.g., vancomycin), lipoglycopeptides (e.g., dalbavancin, oritavancin, telavancin, and teicoplanin), lipopeptides (e.g., daptomycin), and fosfomycin.
• Different classes of antibiotics have varying activity against different types of bacteria.
• Important features to be aware of include spectrum of action, mechanisms of action, and potential side effects.

Penicillins

• Penicillins are a broad class of antibiotics.
• Natural penicillins like penicillin G primarily target gram-positive bacteria, however other types are available like penicillin V which is orally effective.
• Broad-spectrum penicillins include ampicillins, amoxicillins, and others, capable of treating a wider range of gram-positive and negative bacteria.
• Penicillins frequently cause allergies or other allergic reactions in some people.
• Penicillins are susceptible to inactivation by bacterial enzymes, termed beta-lactamases.
• They have a short duration of action.
• Long-acting preparations include procaine penicillin G and benzathine penicillin, which are administered intramuscularly.
• Some penicillins are modified to resist beta-lactamases.

Cephalosporins

• Cephalosporins include several generations with varying activity against different bacterial species.
• Broadening the spectrum, later generations have enhanced effectiveness against gram-negative and anaerobic bacteria.
• Many cephalosporins are beta-lactamase resistant in various generations.
• Adverse effects and cross-reactivity with allergies are significant factors to consider when prescribing these drugs.

Monobactams

• Monobactams are beta-lactam antibiotics like aztreonam.
• These drugs are effective against gram-negative bacteria, not against gram-positive pathogens.
• Often used in cases of penicillin allergy.
• Generally less likely to cause allergies than other β-lactams.

Carbapenems

• Carbapenems, such as imipenem, have a broad spectrum of activity.
• They are effective against a wide range of bacteria, including some resistant strains of gram-positive and gram-negative species.
• Imipenem is usually combined with cilastatin to enhance its stability and potency throughout the body.
• Carbapenems are effective against many gram positive and gram negative organisms.

Other non-β-Lactam Inhibitors

• Glycopeptides (e.g., vancomycin) inhibit bacterial cell wall synthesis and broadly target several gram-positive bacteria.
• Lipoglycopeptides, lipopeptides and fosfomycin have varying clinical applications and can be effective against various forms of gram-positive pathogens but have a narrower spectrum than beta-lactams.
• Polypeptides (e.g., bacitracin), also used topically.
• Important to consider adverse effects like nephrotoxicity.
• Often used in combination or as an alternative choice due to the emergence of bacterial resistance and other factors.

Beta-Lactamase Inhibitors

• Beta-lactamase inhibitors like clavulanate, sulbactam, tazobactam, or avibactam are added to beta-lactam antibiotics. They inhibit the breakdown of the beta-lactams, extending the spectrum or making therapy effective against beta-lactamase-producing bacteria.

Resistance and Combinations

• Bacterial resistance to antibiotics is a significant clinical challenge; therefore, antibiotic combinations or agents with different mechanisms of action are often prescribed.
• Bacterial resistance leads to the need for effective antibiotic treatment options.

Clinical Considerations

• Bacterial resistance patterns, allergies, patient's renal function, and other factors must be considered.
• Combination therapies may be necessary to combat resistance.
• Careful consideration of various factors is crucial when prescribing these types of drugs.

This lesson covers bacterial cell wall inhibitors, a class of antibiotics, and penicillins. It describes β-Lactams and non-β-Lactam inhibitors and provides examples of each. Spectrum of action, mechanisms of action, and potential side effects are important features.