Microbes, collectively, include bacteria, viruses, fungi, and parasites. Antimicrobial drugs, such as antibiotics, have been successfully used to treat patients with bacterial and infectious diseases. Antibiotics may either kill or inhibit the growth of bacteria. Antibiotics are not effective against viruses such as the common cold or influenza.
Cephalosporin antibiotics:
Cephalosporin’s are a group of broad-spectrum antibiotics that are commonly used to treat infections caused by a wide variety of bacteria, including more serious infections such as septicaemia, pneumonia, meningitis, biliary-tract infections, peritonitis, and urinary-tract infections. Cephalosporin Mode of Action, Cephalosporins are a type of B-Lactam antibiotics closely related to the penicillins. They are bactericidal, with the same MOA as other beta-lactams. Cephalosporins disrupt synthesis of the peptidoglycan layer of bacterial cell walls. Peptidoglycan is a strong structural molecule specific to the cells walls of bacteria. With the cell wall structure compromised, the bactericidal result is lysis and death of the cell. Our cells do not have cells walls or peptidoglycan, therefore, B-lactam antibiotics are able to target bacterial cells without harming human cells.
Macrolide antibiotics:
Macrolide antibiotics have an antibacterial spectrum that is similar, but not identical, to that of penicillin, so are often used for people with a penicillin allergy or to treat penicillin-resistant strains of bacteria. Macrolide antibiotics are particular useful for treating lung and chest infections. They are also used for skin infections and some sexually transmitted infections. Macrolides exert their antibiotic effect by binding irreversibly to the 50S subunit of bacterial ribosomes. Ribosomes are the protein factories of the cell, and by binding to the ribosome, macrolides inhibit translocation of tRNA during translation (the production of proteins under the direction of DNA). Although the cells of humans also have ribosomes, these eukaryotic cellular protein factories differ in size and structure from the ribosomes of prokaryotes. This action is mainly bacteriostatic, meaning that bacterial growth and reproduction are inhibited, in contrast to bactericidal antibiotics which directly kill bacteria. Macrolides can be bactericidal in high concentrations.
Penicillin antibiotics:
Penicillin antibiotics are the most widely used groups of antibiotics. They are mainly broad-spectrum antibiotics that can be used for a wide variety of infections, such as respiratory tract infections, skin infections and urinary tract infections. Flucloxacillin is reserved for treating bacteria that are resistant to other penicillin’s. Penicillin’s, and other beta-lactam antibiotics, work by interfering with interpeptide linking of peptidoglycan, the a strong, structural molecule found specifically bacterial cell walls. Cell walls without intact peptidoglycan cross-links are structurally weak, prone to collapse and disintegrate when the bacteria attempt to divide. Since the eukaryotic cells of humans do not have cell walls, our cells are not damaged by penicillin’s.
Quinolone antibiotics:
These are broad-spectrum antibiotics that can be used to treat a wide range of infections, particularly urinary tract and respiratory infections. Quinolones are bactericidal drugs, meaning that they kill bacteria. These antibiotic drugs inhibit the bacterial DNA gyrase enzyme which is necessary for DNA replication. Since a copy of DNA must be made each time a cell divides, interfering with replication makes it difficult for bacteria to multiply. How DNA is packaged is very different in bacteria as opposed to eukaryotes. Bacteria supercoil DNA using DNA gyrase, whereas eukaryotes coil DNA around histone proteins. Because quinolones specifically target DNA gyrase, they do not interfere with human DNA.
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