In vitro activity of gemifloxacin against Helicobacter pylori

Heather W. Minehart and Alison F. Chalker*,

Department of Anti-Infective Research, SmithKline Beecham Pharmaceuticals, 1250 South Collegeville Road, Collegeville, PA 19426-0989, USA

Sir,

The common gastric pathogen Helicobacter pylori is implicated in the development of chronic gastritis, duodenal and gastric ulcers, and gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and there is an established link between H. pylori infection and gastric cancer. Eradication of the infection is often recommended for symptomatic H. pylori-positive patients, particularly those with duodenal or gastric ulcer. However, the efficacy of common triple therapy treatments for H. pylori is being undermined by the rise in frequency of antibiotic-resistant isolates. Although resistance to amoxycillin and tetracycline is rare, substantial and increasing rates of resistance to metronidazole and clarithromycin are a significant cause of treatment failure.1 Hence there is considerable interest in identifying alternative therapies that are more effective against H. pylori.

Fluoroquinolones are widely used for the treatment of gastrointestinal, respiratory and urinary tract infections. Although they are not commonly used to treat H. pylori infections, fluoroquinolones are active in vitro against H. pylori. Recently, the susceptibility of 57 strains of H. pylori taken from human gastric biopsies to 11 antimicrobial agents including four fluoroquinolones was determined.2 The aim of the present study was to evaluate the susceptibility of H. pylori to the new fluoroquinolone gemifloxacin (SB-265805).

Twenty-six H. pylori isolates were obtained, including 16 clinical isolates from CCUG (University of Göteborg, Sweden); four recent clinical isolates from Dr I. Nachamkin (University of Pennsylvania School of Medicine, USA); two isolates from Dr A. Cockayne (University of Nottingham, UK); one isolate from Dr P. Hoffman (Dalhousie University, Canada); and three laboratory control strains. These isolates include gastric biopsy isolates from the USA (4), Sweden (8), France (1), Belgium (2), UK (3), South Africa (1) and Australia (3). Two isolates were reported to have the cagA+ genotype and three to be cagA, but the cag genotype of the rest was unknown. The NCCLS recommended agar dilution method3 was used to determine the activities of gemifloxacin, levofloxacin, ciprofloxacin, moxifloxacin and gatifloxacin against the isolates. The activities of amoxycillin, tetracycline and metronidazole against H. pylori ATCC 43504 were also tested. The agar plates were inoculated using a Steers replicator and read at 72 h.

The control antibiotics amoxycillin, tetracycline and metronidazole gave MICs for H. pylori ATCC 43504 of 0.06, 1.0 and 256 mg/L, respectively, which are within NCCLS quality control breakpoint limits. Gemifloxacin was the most active of the fluoroquinolones tested, followed by gatifloxacin, ciprofloxacin, levofloxacin and moxifloxacin; and was highly active against all H. pylori strains tested, with an MIC90 of 0.13 mg/L (TableGo). There was no apparent correlation of MIC with cag status or geographical location. In conclusion we found that, in comparison with commonly prescribed fluoroquinolones, gemifloxacin demonstrated greater activity against H. pylori strains, including gastric biopsy isolates from various locations worldwide.


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Table. MICs of 26 isolates of H. pylori to fluoroquinolones
 

Notes

J Antimicrob Chemother 2001; 47: 360–361

* Corresponding author. Tel: +1-610-917-6366; Fax: +1-610-917-7901; E-mail: Alison_F_Chalker{at}sbphrd.com Back

References

1 . Alarcon, T., Domingo, D. & Lopez-Brea, M. (1999). Antibiotic resistance problems with Helicobacter pylori. International Journal of Antimicrobial Agents 12, 19–26.[ISI][Medline]

2 . Sanchez, J. E., Saenz, N. G., Rincon, M. R., Martin, I. T., Sanchez, E. G. & Martinez, M. J. (2000). Susceptibility of Helicobacter pylori to mupirocin, oxazolidinones, quinupristin/dalfopristin and new quinolones. Journal of Antimicrobial Chemotherapy 46, 283–5.[Abstract/Free Full Text]

3 . National Committee for Clinical Laboratory Standards. (2000). Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically—Fifth Edition: Approved Standard M7-A5 and MIC Testing Supplemental Tables M100-S10 (M7) Vol. 20 (2). NCCLS, Villanova, PA.