Background: Emergence of antibiotic resistant Helicobacter pylori has neces
sitated the identification of alternate therapies for the treatment of this
Aim: To assess the in vitro efficacy of two investigational agents: DMG-MIN
O CL 344 (a N,N-dimethylglycylamido derivative of minocycline), and daverci
n, a cyclic carbonate of erythromycin A as compared to older antibiotics (c
larithromcyin, azithromycin, minocycline, tetracycline, ofloxacin, ciproflo
xacin, cefixime) against clinical isolates of H. pylori.
Methods: Testing was performed using the agar dilution method approved by t
he NCCLS subcommittee on antimicrobial susceptibility testing, Helicobacter
pylori working group. Under these guidelines, Mueller-Hinton agar containi
ng 5% aged sheep blood was used. All incubations were done under CampyPak P
lus conditions for 72 h at 37 degreesC, The drug concentrations in the agar
ranged from 0.016 to 16 mug/mL. Twenty-one clarithromycin-resistant and 16
clarithromycin-susceptible clinical isolates of H. pylori obtained from pa
tients with duodenal ulcer were used. H. pylori ATCC 43504 was used as the
control in all determinations.
Results: Against clarithromycin susceptible isolates, all antimicrobial age
nts except the fluoroquinolones were highly effective. Against clarithromyc
in-resistant H. pylori, the MIC50/MIC90 values showed that the tetracycline
s and cefixime were the most efficacious agents. The fluoroquinolones and m
acrolides were ineffective, Macrolide cross-resistance was detected.
Conclusion: Macrolide cross-resistance prevents the use of this entire clas
s of antimicrobials when clarithromycin resistance is present. Tetracycline
s and cefixime are possible alternative agents for the treatment of H. pylo
ri infection in these patients.