Gram-positive bacteria quinolones

Regioselective hydrolysis of the diester 27 gave the 1,3-thiazetidine 28 where the thiazetidine ring is fused to a quinolone nucleus <99CPB1765>. Derivatives of the tricyclic system, e.g. 29, showed activity against gram-positive bacteria including quinolone-resistant MRS A <99H(51)2915>. 

Uncomplicated coli Gram-positive bacteria 1. Quinolone x 14 days (A, II)0 2. Trimethoprim-sulfamethoxazole (if susceptible) x 14 days (B, II)0 1. Amoxicillin or amoxicillin-clavulanic acid x 14 days (B, III)0 Can be managed as outpatient... 

Both levofloxacin and ciprofloxacin are quinolones active against both Gramnegative and Gram-positive bacteria. However, levofloxacin has greater activity against pneumoccocci than ciprofloxacin. Levofloxacin may cause tremor and tachycardia as side-effects. All quinolones should be administered with caution in patients with a history of epilepsy. 

It is difluorinated quinolone effective against gram positive bacteria, anaerobes and mycobacteria. It is used in the treatment of pneumonia, chronic bronchitis, sinusitis etc. 

The breakthrough in the development of quinolones came with the appearance of norfloxacin 6 [19], a second-generation quinolone which combined a 6-fluorine substituent with a piperazine ring in the 7-position of the basic compound. Additional quinolones then followed in rapid succession pefloxacin [20], enoxacin [21] and fleroxacin [22] (Fig. 14.5). Particular mention must be made of ciprofloxacin 8 [23-25], ofloxacin 5 [26,27] and its active enantiomer levofloxacin 7 [28]. These quinolones have a broad spectrum of activity, which also includes Gram-positive bacteria and Pseudomonas aeruginosa, as well as favorable pharmacokinetics. The rapid absorption of these compounds from the gastrointestinal tract and their effective tissue penetration also allows them to be used for the treatment of systemic infections. 

Finally, it has to be noted that glycopeptides only represent one option to combat infections by gram-positive bacteria. Current research is focused on other cell wall biosynthesis inhibitors (e.g., (3-lactams, cephalosporins) or even on the development of antibacterial agents (e.g., tetracyclines, ketohdes, and quinolone antibiotics) against other targets.An important drug candidate in this context is hnezolid (Zyvox), which is an entirely synthetic oxazolidinone antibiotic with in vitro and in vivo efficiency against MRS A and VRE. ... 

Piddock L J1994 New quinolones and Gram-positive bacteria. Antimicrobial Agents Chemotherapy 38 163-169... 

The newer quinolones are a class of antibacterial agents with broad-spectrum activities against both gram-negative and gram-positive bacteria. They have... 

Li et al. [23] have synthesized a series of arylhydrazone derivatives bearing a rhodanine moiety and evaluated as antibacterial activity against several different strains of gram-positive bacteria, including multidrug-resistant clinical isolates. Of all the compounds tested, IV and V were identified as the most effective, with minimum inhibitory concentration values of 2-4 pg/mL against methicillin-resistant and quinolone-resistant S. aureus. 

Emami S, Shafiee A, Foroumadi A (2006) Structural features of new quinolones and relationship to antibacterial activity against gram-positive bacteria. Mini-Rev Med Chem 6 375-386... 

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