The emergence of drug resistance since the introduction of antibiotics has led humans to continually search for new antibiotics that defeat evolving pathogens. This has paved the way for the development of various synthetic and semi-synthetic antibiotics with improved efficacy and expanded target coverage. Among several synthetic antibiotics such as sulfonamides, quinolones, and oxazolidinones, quinolones have gained popularity due to their wider application, broader spectrum of activity, and drug safety (Walker, 1999, Saravanos and Duff 1992, Brown, 1996). Therefore, in this section the focus will be on the quinolone class of antibiotics and the mechanism of bacterial resistance against these widely used synthetic antibiotics. Quinolones are the class of antibiotics that specifically kill bacteria by inhibiting the synthesis of nucleic acids. Quinolones are exceptional antibiotics, unlike others that are not isolated from living organisms but obtained by chemical synthesis. The parent quinolone compound, nalidixic acid, was derived from the antimalarial drug chloroquine in 1962 (Bolon, 2011, Andriole, 2005). Nalidixic acid is composed of a naphthyridine ring having ethyl and methyl groups attached to its N1 and C7 positions respectively along with keto and carboxyl groups attached to its C4 and C3 positions respectively. Although it has narrow-spectrum antibacterial activity, it was widely used for urinary tract infections and diarrhea until the introduction of broad-spectrum fluoroquinolones (Bambeke et al 2005, Drilca and Zhao, 1997). Fluoroquinolones were derived from nalidixic acid by introducing a fluorine atom at the C6 position of the naphthyridine ring and also replacing the N8 with a carbon atom (Ball, 2000). All available quinolones... middle of paper... ...ivate quinolones (ciprofloxacin and norfloxacin) by N-acetylation of the amino nitrogen on its piperazinyl group. Two amino acid changes (Trp102Arg and Asp179Tyr) further increased the enzyme's ability to inactivate quinolones in addition to aminoglycosides. The effect on the MIC by AAC(6')-Ib-cr is less than that conferred by the Qnr protein and the pharmacological spectrum covered by this enzyme is also small (only ciprofloxacin and norfloxacin). It is reasonably well documented that quinolone resistance in pathogenic bacteria through intrinsic and acquired traits causes a serious health problem. The synergistic action of all these factors transmitted by chromosomes and plasmids helps the pathogen to confer a higher level of resistance to quinolones, as described by many researchers (Baranwal et al. 2002, Rushdy et al. 2013, Srinivasan et al. 2006, Zhu et al. al.2013).Works citedhfrjfrtj