In vitro antibacterial spectrum of a new broad-spectrum 8-methoxy fluoroquinolone, gatifloxacin

Abstract

The in vitro antibacterial spectrum of gatifloxacin was compared with those of ciprofloxacin and ofloxacin. Gatifloxacin was two- to four-fold more potent than comparator quinolones against staphylococci, streptococci, pneumococci and enterococci (gatifloxacin MIC90s, < or =1 mg/L, except 4 mg/L against methicillin-resistant Staphylococcus aureus and Enterococcus faecium). Gatifloxacin was two-fold less potent than ciprofloxacin, and the same as or two-fold more potent than ofloxacin against Enterobacteriaceae (MIC90s, 0.06-0.5 mg/L against most members of the Enterobacteriaceae and < or =1 mg/L against Proteus/Morganella spp.). Relative to the comparator quinolones, gatifloxacin was two- to four-fold more potent against Providencia spp., and had good potency against Acinetobacter spp. (MIC90s, 0.25-1 mg/L). Gatifloxacin and ofloxacin had similar anti-pseudomonal potency, with corresponding MIC90s of 4, 8 and 0.25 mg/L for Pseudomonas aeruginosa, Pseudomonas fluorescens and Pseudomonas stutzeri, while ciprofloxacin had two- to eight-fold more potency. The three quinolones were equipotent against Burkholderia cepacia (MIC90s, 8 mg/L), but gatifloxacin was two-fold more potent against Stenotrophomonas maltophilia (MIC90, 4 mg/L). Gatifloxacin was highly potent (MIC90s, 0.03-0.06 mg/L) against Haemophilus influenzae, Legionella spp., Helicobacter pylori and had at least eight-fold better anti-chlamydial and anti-mycoplasma potency (gatifloxacin MIC90s, 0.13 mg/L). The higher quinolone MICs for ureaplasma (MIC90s, 4-8 mg/L) may be due to the acidic pH of the ureaplasma test medium, which antagonizes quinolones. Like other quinolones, gatifloxacin had poor potency against Mycobacterium avium-intracellulare, though it was eight- to 16-fold more potent against Mycobacterium tuberculosis (MIC90, 0.25 mg/L). Of the three quinolones, only gatifloxacin had activity against Bacteroides fragilis and Clostridium difficile. In summary, gatifloxacin is a broad-spectrum 8-methoxy fluoroquinolone that is more potent than ciprofloxacin and ofloxacin against Gram-positive bacteria, chlamydia, mycoplasma, mycobacteria and anaerobes.

Incidence of Moxifloxacin Resistance in Clinical Mycobacterium tuberculosis Isolates in Houston, Texas

“…Their tolerability and relative low to moderate cost have made them an attractive target for development as antituberculosis drugs. The newer quinolones, such as sparfloxacin, gatifloxacin, and moxifloxacin, have better in vitro activity against Mycobacterium tuberculosis clinical isolates than older quinolones, such as ofloxacin, levofloxacin and ciprofloxacin, as suggested by lower MICs, a higher ratio of the peak serum drug concentration to the MIC, and a higher ratio of the 24-h area under the curve to the MIC (11,22,(27)(28)(29)36). In vivo studies in animal models and humans have corroborated these findings (19,34).…”

In Vitro Activities of the Newer Quinolones Garenoxacin, Gatifloxacin, and Gemifloxacin against Human Mycoplasmas

“…Garenoxacin exhibited the highest activity, followed by gemifloxacin, moxifloxacin, and gatifloxacin. The minimal bactericidal activities of these three compounds were lower than those of the four fluoroquinolones.Garenoxacin, a des-fluoro(6)-quinolone, and gemifloxacin and gatifloxacin, two fluoroquinolones, are new compounds of the widespread class of fluoroquinolones with potent antibacterial activity against gram-negative, gram-positive, and anaerobic bacteria (6)(7)(8)11). The different fluoroquinolones show various levels of activity against mycoplasmas.…”

Effectiveness, safety and tolerability of gatifloxacin, a new 8-methoxyfluoroquinolone, in the treatment of outpatients with community-acquired pneumonia: a Brazilian study

“…Gatifloxacin is a new advanced generation 8-methoxifluoroquinolone that has an expanded spectrum of activity compared with previous generation quinolones [10,11]. It is active against gram-positive pathogens, including penicillin-resistant strains of S. pneumoniae and methicillin-susceptible S. aureus; gram-negative microorganisms, including H. influenzae and M. catarrhalis; atypical pathogens, such as Mycoplasma, Legionella and Chlamydia sp.…”