Antimicrobials quinolones

Antibacterials. See Antibacterial agents Antibiotics Antimicrobials Quinolone antibacterials... 

As the two strands of the double helix are separated, positive supercoils are produced in the region of DNA ahead of the replication fork. These interfere with further unwinding of the double helix. DNA topoisomerases Types I and II remove supercoils. Human topoiso-merase II is targeted by anticancer agents, such as etoposide, and DNA gyrase (a Type II topoisomerase found in E. coli that can introduce negative supercoils) is targeted by the antimicrobial quinolones. 

The autoinducer of the third quorum sensing system in P. aeruginosa is PQS. (Figure 36) PQS is involved in lasB expression, and RhlR is required for PQS activity. The structure of PQS is similar to that of antimicrobial quinolones, but PQS shows no antimicrobial activity. PQS is converted from 2-heptyl-4(lH)-quinolone (HHQ) by PqsH, which is activated by 3-oxo-Cl2-HSL—LasR. PQS regulates the expression of elastase, rhamnolipid, pyocyanin, and LecA. As PQS regulates LasB expression and the synthesis of PQS is regulated by LasR and... 

The generally accepted structure-activity relationships developed in the early work in the quinolone series held that the N-1 substituent needed to be small and aliphatic. This picture was upset in a dramatic way with the discovery of the excellent potency and antimicrobial spectrum of difloxacin (45) and its congeners in which the substituent on N-1 is an aromatic ring. The synthe-... 

A fluorine atom in position 6 of the basic structure of quinolones enhances the antimicrobial activity considerably. All widely used quinolones are fluorinated in position 6 and the term fluoroquinolones is often used to describe these drugs. However, some new quinolones with similar antimicrobial activity are not fluorinated in position 6 (e.g. garenoxacin, PGE9262932) and therefore the term quinolones is more appropriate to describe this group of antimicrobial agents. 

As with all drugs, the specific side effects of the quinolones must be considered when they are chosen for treatment of bacterial infections [5]. Reactions of the gastrointestinal tract and the central neivous system are the most often observed adverse effects during therapy with quinolones. It should be underlined, however, that compared with many other antimicrobials, diarrhea is less frequently observed during quinolone treatment. Antibiotic-associated colitis has been observed rarely during quinolone therapy. Similarly, hypersensitivity reactions, as observed during therapy with penicillins and other (3-lactams, is less frequently caused by quinolones. Some other risks of quinolone therapy have been defined and must be considered if a drug from this class is chosen for treatment of bacterial infections. 

Gootz TD, Osheroff N (1993) Quinolones and eukaryotic topoisomerases. In Hooper DC and Wolfson JS (eds) Quinolone antimicrobial agents, 2nd edn. American Society for Microbiology, Washington, DC, pp 139-160... 

Hooper D.C. Wolfson J.S. (eds) (1993) Quinolone Antimicrobial Agents, 2nd edn. Washington American Society for Microbiology. 

Allopurinol, barbiturates, carbamazepine, cephalosporins, cyclophosphamide, ethambutol, fluconazole, ibuprofen, lamotrigine, macrolides, nitrofurantoin, penicillins, phenytoin, propranolol, quinolones, sulfonamide antimicrobials, sulindac, tetracyclines, thiazides, valproic acid, and vancomycin... 

Although not reviewed in detail here, C. jejuni and C. coli are another major cause of inflammatory colitis that may be complicated by Guillain-Barre syndrome or reactive arthritis. In addition, their resistance to antimicrobials (particularly to quinolones) is increasing. In the United States, fluoroquinolone resistance of C. jejuni rose from 13% in 1997 to 18% in 1999 [112],... 

Completion of the antimicrobial course with oral forms of a quinolone plus metronidazole,... 

Naruhashi K, Tamai I, Inoue N, Muraoka H, Sai Y, Suzuki N, Tsuji A (2001) Active intestinal secretion of new quinolone antimicrobials and the partial contribution of P-glycoprotein. J Pharm Pharmacol 53 699-709. 

Rifamycin- quinolone heterodimer Antibiotics CBR-2092 (156) Antibacterial Bcerts antimicrobial activity through combined effects on RNA polymerase, DNA topoisomerase IV and DNA gyrase Phase Ila (treatment of infections caused by Gram-positive cocci) Cumbre Pharmaceuticals 819, 820... 

Quinolones are a group of structurally similar antimicrobial drugs that exhibit high activity against many microorganisms. 

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