Question

Which of the following is not a type of \(\beta\) -lactam antimicrobial? a. penicillins b. glycopeptides c. cephalosporins d. monobactams

Short answer

b. glycopeptides

Step-by-step solution

- Understand \(\beta\) -lactam antimicrobials

\(\beta\) -lactam antimicrobials are a class of broad-spectrum antibiotics that include a beta-lactam ring in their molecular structures. These antibiotics are known for inhibiting bacterial cell wall synthesis.

- Identify \(\beta\) -lactam antimicrobial types

The common types of \(\beta\) -lactam antimicrobials include penicillins, cephalosporins, monobactams, and carbapenems. These antibiotics share the beta-lactam ring structure and similar mechanisms of action.

- Identify the non-\(\beta\) -lactam option

The question asks which of the provided options is not a type of \(\beta\) -lactam antimicrobial. Compare the list of \(\beta\) -lactam types with the provided options: penicillins, glycopeptides, cephalosporins, and monobactams. Glycopeptides do not have a beta-lactam ring and thus do not fall under the \(\beta\) -lactam class.

Key concepts

penicillins

Penicillins are a group of antibiotics derived from Penicillium fungi. These antibiotics are noted for their ability to inhibit the synthesis of bacterial cell walls. One of the key features of penicillins is the beta-lactam ring in their chemical structure, which is crucial for their antibacterial activity. When penicillins inhibit the enzyme responsible for cell wall formation, bacteria cannot build a proper cell wall, leading to their death. Some common examples of penicillins include penicillin G, penicillin V, amoxicillin, and ampicillin. Despite their effectiveness, some bacteria have developed resistance to penicillins, often through the production of beta-lactamase enzymes that break down the beta-lactam ring.

cephalosporins

Cephalosporins are another broad class of beta-lactam antibiotics. They have a similar mechanism of action to penicillins, targeting bacterial cell wall synthesis. The major difference lies in their chemical structure, which makes cephalosporins generally more resistant to beta-lactamase enzymes. Cephalosporins are categorized into different generations, each differing in their spectrum of activity:

• First-generation cephalosporins like cefalexin are effective against gram-positive bacteria.
• Second-generation cephalosporins like cefuroxime have expanded activity against gram-negative bacteria.
• Third-generation cephalosporins like ceftriaxone have even broader gram-negative activity and can penetrate the blood-brain barrier.
• Fourth and fifth-generation cephalosporins like cefepime and ceftaroline provide solutions for certain resistant bacteria.

Cephalosporins are often used in surgical prophylaxis and treating infections of the lungs, skin, soft tissues, and urinary tract.

monobactams

Monobactams are a unique subset of beta-lactam antibiotics. Unlike other beta-lactams, monobactams have a monocyclic beta-lactam ring. Aztreonam is the most well-known monobactam and is particularly effective against gram-negative bacteria, including Pseudomonas aeruginosa. Monobactams work by inhibiting bacterial cell wall synthesis, similar to penicillins and cephalosporins. One of the advantages of monobactams is their ability to resist beta-lactamases, Enzymes that may break down other types of beta-lactams. Monobactams are typically used to treat severe infections like sepsis and pneumonia.

glycopeptides

Glycopeptides represent a different class of antibiotics that do not fall under the beta-lactam category. These antibiotics, including vancomycin and teicoplanin, are crucial for infections caused by gram-positive bacteria, especially those resistant to beta-lactams. Glycopeptides work by inhibiting cell wall synthesis, but they bind to different targets from beta-lactams. Instead of binding to enzymes, glycopeptides attach directly to the cell wall precursors, blocking the construction of the bacterial cell wall. Glycopeptides are often reserved for resistant strains like MRSA (methicillin-resistant Staphylococcus aureus) and are critical in a clinical setting when first-line antibiotics fail to work.