Antimicrobial Drugs PDF

Aminoglycosides Streptomycin, kanamycin, gentamicin, tobramycin, amikacin are antibiotics exert their effort by passing through the bacterial outer membrane (in gram- negative bacteria), cell wall, and cytoplasmic membrane to the cytoplasm, where they inhibit bacterial protein synthe...

Aminoglycosides Streptomycin, kanamycin, gentamicin, tobramycin, amikacin are antibiotics exert their effort by passing through the bacterial outer membrane (in gram- negative bacteria), cell wall, and cytoplasmic membrane to the cytoplasm, where they inhibit bacterial protein synthesis by irreversibly binding to the 30S ribosomal proteins, Streptomycin producing aberrant proteins as the result of misreading of the messenger RNA (mRNA) and interruption of protein synthesis by causing the premature release of the ribosome from mRNA. Glycoside (sugar) They are not absorbed from the gut, Amino groups they are administered intravenously and intramuscularly.  Discovery of streptomycin Discovered in 1943 from Streptomyces griseus of Actinobacteria Selman Waksman (1888-1973) and Albert Schatz (1920-2005) codiscoverers of streptomycin. A rift between the inventors over royalty shares on patent (No. 2,449,866, Sept. 21,1948, "streptomycin and process of preparation,") and the noble prize which is only awarded to Selman Waksman in 1952. https://www.the-scientist.com/?articles.view/articleNo/25252/title/The-discovery-of-streptomycin/ E타AM Nucleic acid synthesis as a drug target ∅ – Quinolones are antibacterial compounds that interfere with DNA gyrase. (e.g., ciprofloxacin) √. ㄴ  Quinolones The quinolones are one of the most widely used classes of antibiotics. These are synthetic chemotherapeutic agents that inhibit bacterial DNA topoisomerase type II (gyrase) or topoisomerase type IV, which are required for DNA replication, recombination, and repair. This drug has now been replaced by newer, more active quinolones, such as ciprofloxacin, levofloxacin, and moxifloxacin. Resistance to the quinolones is mediated by chromosomal mutations in the structural genes for DNA gyrase and topoisomerase type IV. Other mechanisms include decreased drug uptake caused by mutations in the membrane permeability regulatory genes, and overexpression of efflux pumps that actively eliminate the drug. ( Refer to above figurc fr Other antibacterial drug targets exard – Growth factor analogs are structurally similar to growth factors but do not function in the cell. analogs similar to vitamins, amino acids, and other compounds Folic acid synthesis inhibitor: Sulfonamides are antimetabolites that compete with p-aminobenzoic acid, thereby preventing the synthesis of the folic acid. Because mammalian organisms do not synthesize folic acid (required as a vitamin), folic acid metabolism is a good target for antibiotics. – Isoniazid is a growth analog effective only against Mycobacterium. interferes with synthesis of mycolic acid – daptomycin used to treat gram-positive bacterial infections forms pores in cytoplasmic membrane – platensimycin new structural class of antibiotic: inhibiting fatty acid biosynthesis pathway in bacteria broad-spectrum; effective against MRSA and vancomycin-resistant enterococci  28.11 Antimicrobial Drugs That Target Nonbacterial Pathogens Antiviral drugs – Most antiviral drugs also target host structures, resulting in toxicity. (Table 28.6) – Most successful and commonly used antivirals are the nucleoside analogs. (e.g., AZT) block reverse transcriptase and production of viral DNA also called nucleoside reverse transcriptase inhibitors (NRTIs) – Nonnucleoside reverse transcriptase inhibitors (NNRTIs) bind directly to RT and inhibit reverse transcription. – Protease inhibitors inhibit the processing of large viral proteins into individual components. – Fusion inhibitors prevent viruses from successfully fusing with the host cell.  Antiviral drugs – Neuraminidase inhibitors (e.g., Tamiflu) successfully limit influenza infection. – Interferons are small proteins that prevent viral multiplication by stimulating antiviral proteins in uninfected cells. Drugs that target eukaryotic pathogens Drugs that target eukaryotic pathogens – Fungi pose special problems for chemotherapy because they are eukaryotic. (Figure 28.32) Much of the cellular machinery is the same as that of animals and humans. As a result, many antifungals are topical.  EFAM & _ \ 、 √ _ Figure 28.32  A few drugs target unique metabolic processes unique to fungi, such as cell wall synthesis. – Ergosterol inhibitors target the unique fungal plasma membrane component ergosterol. – Echinocandins inhibit 1,3 -D glucan synthase and are used to treat Candida infections. Other drugs target chitin biosynthesis, target folate biosynthesis, or disrupt microtubule aggregation. Like antibiotic resistance, antifungal resistance is on the rise. ( Dont need torenenba fr exm)