antibiotic

Examples of antibiotic in the following topics:

• History of Antibiotic Therapy

• Antibiotic Misuse

  • Antibiotic resistance occurs when antibiotics no longer work against disease-causing bacteria.
  • Developing new antibiotics and other treatments to keep pace with antibiotic-resistant strains of bacteria is necessary.
  • Antibiotic misuse has contributed largely to the emergence of new resistant strains.
  • It can also be manifested by not finishing a course of antibiotics as prescribed (stopping the antibiotic before the infection is fully cleared from the body).
  • Antibiotics are not effective against viral infections.

• Antibiotic Classifications

  • Bactericidal antibiotics kill bacteria; bacteriostatic antibiotics slow their growth or reproduction.
  • Antibiotics can be divided into two classes based on their mechanism of action.
  • Bactericidal antibiotics kill bacteria; bacteriostatic antibiotics inhibit their growth or reproduction.
  • However, there is not always a precise distinction between them and bactericidal antibiotics.
  • "Narrow-spectrum" antibacterial antibiotics target specific types of bacteria, such as Gram-negative or Gram-positive bacteria, whereas broad-spectrum antibiotics affect a wide range of bacteria, usually both gram positive and gram negative cells.

• Kirby-Bauer Disk Susceptibility Test

  • Kirby-Bauer antibiotic testing (also called KB testing or disk diffusion antibiotic sensitivity testing) uses antibiotic-containing wafers or disks to test whether particular bacteria are susceptible to specific antibiotics.
  • A larger zone of inhibition around an antibiotic-containing disk indicates that the bacteria are more sensitive to the antibiotic in the disk.
  • Clinicians can use KB test results to choose appropriate antibiotics to combat a particular infection in a patient.
  • Administering antibiotics that specifically target the particular bacteria that are causing the infection can avoid using broad-spectrum antibiotics, which target many types of bacteria.
  • In Kirby–Bauer testing, discs containing antibiotics are placed on agar where bacteria are growing, and the antibiotics diffuse out into the agar.

• Antibiotics from Prokaryotes

  • Even though penicillin drugs, antibiotics produced by molds, were the first antibiotics successfully used to treat many serious infections, most of the naturally produced antibiotics are synthesized by bacteria.
  • These were the first antibiotics to be manufactured commercially.
  • They produce over two-thirds of the clinically useful antibiotics of natural origin .
  • Other bacterial species produce antibiotics as well.
  • Explain the role of Streptomyces and other prokaryotes in antibiotic production

• Antibiotics and Selective Toxicity

  • Antibiotics are able to selectively target specific types of bacteria without harming the infected host.
  • More specifically, narrow spectrum antibiotics target specific types of bacteria, such as Gram-negative or Gram-positive bacteria, whereas broad spectrum antibiotics affect a wide range of bacteria.
  • Other antibiotics simply lack advantage over those already in use, or have no other practical applications.
  • Useful antibiotics are often discovered using a screening process.
  • Most antibiotics identified in such a screen are already known and must therefore be disregarded.

• Industrial Production of Antibiotics

  • Once the process is complete, the antibiotic must be extracted and purified to a crystalline product.
  • This is simpler to achieve if the antibiotic is soluble in organic solvent.
  • This is because species are often genetically modified to yield the maximum amounts of antibiotics.
  • This process must be closely linked with retesting of antibiotic production and effectiveness.
  • Useful antibiotics are often discovered using a screening process.

• Spectrum of Antimicrobial Activity

  • The range of bacteria that an antibiotic affects can be divided into narrow spectrum and broad spectrum.
  • Broad spectrum—antibiotics act against gram positive and gram negative bacteria, for example amoxicillin.
  • A broad spectrum antibiotic acts against both Gram-positive and Gram-negative bacteria, in contrast to a narrow spectrum antibiotic, which is effective against specific families of bacteria.
  • An example of a commonly used broad-spectrum antibiotic is ampicillin.
  • Broad spectrum antibiotics are also used for drug resistant bacteria that do not respond to other, more narrow spectrum antibiotics and in the case of superinfections, where there are multiple types of bacteria causing illness, thus warranting either a broad-spectrum antibiotic or combination antibiotic therapy.

• Beta-Lactam Antibiotics: Penicillins and Cephalosporins

  • The β-lactam ring is part of the core structure of several antibiotic families.
  • The β-lactam ring is part of the core structure of several antibiotic families, the principal ones being the penicillins, cephalosporins, carbapenems, and monobactams, which are, therefore, also called β-lactam antibiotics.
  • Nearly all of these antibiotics work by inhibiting bacterial cell wall biosynthesis.
  • Penicillin (sometimes abbreviated PCN or pen) is a group of antibiotics derived from Penicillium fungi.
  • Together with cephamycins, they constitute a subgroup of β-lactam antibiotics called cephems.

• Inhibiting Cell Wall Synthesis

  • β-Lactam (beta-lactam) and glycopeptide antibiotics work by inhibiting or interfering with cell wall synthesis of the target bacteria.
  • The first class of antimicrobial drugs that interfere with cell wall synthesis are the β-Lactam antibiotics (beta-lactam antibiotics), consisting of all antibiotic agents that contains a β-lactam nucleus in their molecular structures.
  • PBPs vary in their affinity for binding penicillin or other β-lactam antibiotics.
  • To overcome this resistance, β-lactam antibiotics are often given with β-lactamase inhibitors such as clavulanic acid.
  • Significant glycopeptide antibiotics include vancomycin, teicoplanin, telavancin, bleomycin, ramoplanin, and decaplanin.