Indication:
Gatifloxacin is bactericidal and acts by inhibiting the A subunit of DNA gyrase (topoisomerase) which is essential in the reproduction of bacterial DNA. It has a broader spectrum of activity and is more potent in vitro than the non-fluorinated quinolone nalidixic acid. Activity may be reduced in acid media.
Spectrum of activity Among Gram-negative aerobic bacteria, Gatifloxacin is active in vitro against Enterobaceriaceae, including Escherichia coli and Citrobacter, Enterobacter, Klebsiella, Proteus, Providencia, Salmonella, Serratia, Shigella, and Yersinia spp; the MIC90 for most of these is reported to be 1µg or less per mL. It (MIC90 about 2µg per mL), but less so against other Pseudomonas spp. Haemophilus ducreyi,H. influenzas, Morexella catarrhalis (Branhamella catarrh list), Neisseria gonorrhea, and N. meningitides are all very sensitive, including beta-lantanas-producing strains of H. influenza, M. catarrhalis, and N. gonorrhea. Other Gram-negative aerobic bacteria reported to be sensitive to Gatifloxacin have include Acinetobacter spp., Campylobacter spp., Gardnerella vaginalis, Helicobacter pylori.
Among Gram-positive aerobic bacteria, Gatifloxacin is active against staphylococci, including penicillinase-producing and penicillinase-nonproducing strains (MIC90 1 µg or less per mL), and against some meticillin-resistant strains. Streptococci, are less susceptible. Other Gram-positive bacteria sensitive to Gatifloxacin in vitro are Corynebacterium spp. and Lisreria monocytogenes.
Most anaerobic bacteria, including Bacteroides fragilis and Clostridium difficult, are resistance to Gatifloxacin, although some other Bacteroides and Clostridium spp. may be susceptible.
Gatifloxacin has some activity against mycobacterium, mycoplasmas, reckettsias, and the protozoan Plasmodium falciparum. Chlamydia trachomatis is not very susceptible and Nocardia asteroides and Ureaplasma urealyticum are usually considered to be resistant. The spirochaets Treponema pallidum and fungi are also resistant.
Activity with other antimicrobial agents. There have been some reports of enhanced activity in vitro when gatifloxacin has been used with other antimicrobials, such as azlocillin against Staphylococcus aureus and Pseudomonas aeruginosa, imipenem against Ps. Aeruginosa, and cefotaxime or clindamycin against anaerobic bacteria.
