What is the mechanism of action of quinolone or fluoroquinolone antibiotics?

What is the mechanism of action of quinolone or fluoroquinolone antibiotics?

What is the mechanism of action of quinolone or fluoroquinolone antibiotics?

Mechanism of action Quinolones inhibit replication of bacterial DNA by blocking the ligase domain of bacterial DNA gyrase (topoisomerase II); some also inhibit topoisomerase IV. These enzymes relax DNA supercoils and enable DNA replication and repair (see Fig. 51.1). The effect of quinolones is bactericidal.

What is mechanism of action sulfonamides antibiotic drugs?

Sulfa drugs work by binding and inhibiting a specific enzyme called dihydropteroate synthase (DHPS). This enzyme is critical for the synthesis of folate, an essential nutrient. Mammals get folate from their diet, but bacteria must synthesize this vitamin.

What is antibiotic resistance mechanism and synergism?

Antibiotic synergy is one of three responses possible when two or more antibiotics are used simultaneously to treat an infection. In the synergistic response, the applied antibiotics work together to produce an effect more potent than if each antibiotic were applied singly.

What are the mechanisms of action of antibiotics?

Five Basic Mechanisms of Antibiotic Action against Bacterial Cells:

  • Inhibition of Cell Wall Synthesis.
  • Inhibition of Protein Synthesis (Translation)
  • Alteration of Cell Membranes.
  • Inhibition of Nucleic Acid Synthesis.
  • Antimetabolite Activity.

    What is a contraindication to use of a fluoroquinolone?

    Quinolones are contraindicated if a patient has epilepsy, QT prolongation, pre-existing CNS lesions, or CNS inflammation, or the patient has suffered a stroke. They are best avoided in the athlete population.

    What is the mechanism of action of fluoroquinolones *?

    The formation of the ternary complex of quinolone, DNA, and either DNA gyrase or topoisomerase IV occurs through interactions in which quinolone binding appears to induce changes in both DNA and the topoisomerase that occur separately from the DNA cleavage that is the hallmark of quinolone action.

    What is penicillin mechanism of action?

    Penicillin kills susceptible bacteria by specifically inhibiting the transpeptidase that catalyzes the final step in cell wall biosynthesis, the cross-linking of peptidoglycan.

    How do sulfonamides affect bacteria?

    The sulfa drugs such as sulfonamides inhibit a critical enzyme–dihydropteroate synthase–in this process. Once the process is stopped, the bacteria can no longer grow. Another kind of antibiotic–tetracycline–also inhibits bacterial growth by stopping protein synthesis.

    What are the five mechanisms of antimicrobial drug action?

    There are six major modes of action: (1) interference with cell wall synthesis, (2) inhibition of protein synthesis, (3) interference with nucleic acid synthesis, (4) inhibition of a metabolic pathway, (5) inhibition of membrane function, (6) inhibition of ATP Synthase (Fig. 1).

    What are the classification of antibiotics according to action?

    Antibiotics can be divided into two classes based on their mechanism of action. Bactericidal antibiotics kill bacteria; bacteriostatic antibiotics inhibit their growth or reproduction.

    Which of the following is advantage of Fluroquinolones over quinolones?

    Advantages of the new fluoroquinolones may include treating bacteria that are resistant to some of the older fluoroquinolones such as ciprofloxacin. For S pneumoniae, the primary target is fluoroquinolone dependent. The primary target for ciprofloxacin, levofloxacin, moxifloxacin and trovafloxacin is ParC (40,41).

    What are fluoroquinolone antibiotics used to treat?

    The fluoroquinolones are indicated for treatment of several bacterial infections, including bacterial bronchitis, pneumonia, sinusitis, urinary tract infections, septicemia and intraabdominal infections, joint and bone infections, soft tissue and skin infections, typhoid fever, anthrax, bacterial gastroenteritis.

    What is the function of fluoroquinolones?

    Fluoroquinolones (see table Fluoroquinolones) exhibit concentration-dependent bactericidal activity by inhibiting the activity of DNA gyrase and topoisomerase, enzymes essential for bacterial DNA replication.

    How do sulfonamides destroy bacteria?

    Sulfa drugs kill bacteria and fungi by interfering with cell metabolism. They were the wonder drugs before penicillin and are still used today. Because sulfa drugs concentrate in the urine before being excreted, treating urinary tract infections is one of their most common uses.

    What type of cell are bacteria?

    Prokaryotic cells
    Prokaryotic cells (i.e., Bacteria and Archaea) are fundamentally different from the eukaryotic cells that constitute other forms of life. Prokaryotic cells are defined by a much simpler design than is found in eukaryotic cells.

    What is the mechanism of antibiotic resistance?

    The three fundamental mechanisms of antimicrobial resistance are (1) enzymatic degradation of antibacterial drugs, (2) alteration of bacterial proteins that are antimicrobial targets, and (3) changes in membrane permeability to antibiotics.

    What are the types of antibiotic resistance?

    Bacteria resistant to antibiotics

    • methicillin-resistant Staphylococcus aureus (MRSA)
    • vancomycin-resistant Enterococcus (VRE)
    • multi-drug-resistant Mycobacterium tuberculosis (MDR-TB)
    • carbapenem-resistant Enterobacteriaceae (CRE) gut bacteria.

      How does sulfonamide work as an antibiotic for bacteria?

      Sulfonamide antibiotics work by interfering with folic acid synthesis in susceptible organisms, due to their structural similarity to para-aminobenzoic acid (PABA) in bacterial cells. Folic acid is essential for nucleic acid synthesis. When used alone, sulfonamide antibiotics are bacteriostatic to susceptible organisms.

      What happens when sulfonamide and diaminopyrimidine are combined?

      Diaminopyrimidines such as trimethoprim inhibit dihydrofolate reductase, which is further into the folic acid synthesis pathway. The combination of a sulfonamide and a diaminopyrimidine results in synergistic, bactericidal actions on susceptible organisms; as such, the combination is referred to as a “potentiated” sulfonamide.

      What makes quinolone an effective antibiotic to kill bacteria?

      The ability of quinolone antibiotics to kill bacteria is a function of the stable interaction complex formed between drug-bound topoisomerase enzyme and cleaved DNA.

      How does antibiotic quinolone interfere with DNA gyrase?

      The quinolone class of antimicrobials interferes with the maintenance of chromosomal topology by targeting DNA gyrase (topoisomerase II) and topoisomerase IV (topoIV), trapping these enzymes at the DNA cleavage stage and preventing strand rejoining 4, 19, 20 ( Figure 1a ).