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Quinolone antibiotic
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<p>Quinolone antibiotics constitute a large group of <a href="/facts/Broad-spectrum_antibiotic/gITH5ecM">broad-spectrum</a> <a href="/facts/Bacteriocidal/X1XwY97r">bacteriocidals</a> that share a <a href="/facts/Bicyclic_molecule/WfstMqT6">bicyclic core structure</a> related to the substance <a href="/facts/4-Quinolone/1h8jznSQ">4-quinolone</a>. They are used in human and veterinary medicine to treat bacterial <a href="/facts/Infection/182XrncP">infections</a>, as well as in <a href="/facts/Animal_husbandry/aJforlQp">animal husbandry</a>, specifically <a href="/facts/Poultry_production/kPvAqgeV">poultry production</a>. </p><p>Quinolone antibiotics are classified into four generations based on their spectrum of activity and chemical modifications. The first-generation quinolones, such as nalidixic acid, primarily target Gram-negative bacteria and are mainly used for urinary tract infections. Second-generation quinolones introduced fluorine atoms into their structure, creating fluoroquinolones, which significantly expanded their antibacterial activity to include some Gram-positive bacteria. Third-generation fluoroquinolones further improved Gram-positive coverage, while fourth-generation fluoroquinolones offer broad-spectrum activity, including anaerobic bacteria. </p><p>Only quinolone antibiotics in generation two and higher are considered fluoroquinolones, as they contain a <a href="/facts/Fluorine/YUV0Fb8m">fluorine</a> atom in their chemical structure and are effective against both <a href="/facts/Gram-negative/S1PbVtp4">Gram-negative</a> and <a href="/facts/Gram-positive/H6WYQ17e">Gram-positive</a> bacteria. One example is <a href="/facts/Ciprofloxacin/RNAy8SHB">ciprofloxacin</a>, one of the most widely used antibiotics worldwide. </p>