Helicobacter cinaedi bacteremia resulting from antimicrobial resistance acquired during treatment for X-linked agammaglobulinemia.

This is the first report of penicillin/cephalosporin-resistant Helicobacter cinaedi arising from prolonged treatment. H. cinaedi, common among immunocompromised patients, caused recurrent bacteremia and cellulitis in a 19-year-old Japanese man with X-linked agammaglobulinemia. The minimal inhibitory concentration of these drugs was raised, which subsequently resulted in clinical failure. Prolonged suboptimal treatment may cause bacterial resistance to ß-lactam antibiotics in H. cinaedi. It is possible that this resistance may have contributed to the treatment failure.

Oral glutathione supplementation drastically reduces Helicobacter-induced gastric pathologies.

Helicobacter (H.) suis causes gastric pathologies in both pigs and humans. Very little is known on the metabolism of this bacterium and its impact on the host. In this study, we have revealed the importance of the glutamate-generating metabolism, as shown by a complete depletion of glutamine (Gln) in the medium during H. suis culture. Besides Gln, H. suis can also convert glutathione (GSH) to glutamate, and both reactions are catalyzed by the H. suis γ-glutamyltranspeptidase (GGT). Both for H. pylori and H. suis, it has been hypothesized that the degradation of Gln and GSH may lead to a deficiency for the host, possibly initiating or promoting several pathologies. Therefore the in vivo effect of oral supplementation with Gln and GSH was assessed. Oral supplementation with Gln was shown to temper H. suis induced gastritis and epithelial (hyper)proliferation in Mongolian gerbils. Astonishingly, supplementation of the feed with GSH, another GGT substrate, resulted in inflammation and epithelial proliferation levels returning to baseline levels of uninfected controls. This indicates that Gln and GSH supplementation may help reducing tissue damage caused by Helicobacter infection in both humans and pigs, highlighting their potential as a supportive therapy during and after Helicobacter eradication therapy.

Analysis and anti-Helicobacter activity of sulforaphane and related compounds present in broccoli ( Brassica oleracea L.) sprouts.

A crude methanol extract prepared from fresh broccoli sprouts was extracted with hexane, chloroform, ethyl acetate, and butanol sequentially. Residual water fraction was obtained from the residual aqueous layer. The greatest inhibition zones (>5 cm) were noted for Helicobacter pylori strain by the chloroform extract, followed by the hexane extract (5.03 cm), the ethyl acetate extract (4.90 cm), the butanol extract (3.10 cm), and the crude methanol extract (2.80 cm), whereas the residual water fraction did not show any inhibition zone. Including sulforaphane, five sulforaphane-related compounds were positively identified in the chloroform extract, of which 5-methylsulfinylpentylnitrile was found in the greatest concentration (475.7 mg/kg of fresh sprouts), followed by sulforaphane (222.6 mg/kg) and 4-methylsulfinylbutylnitrile (63.0 mg/kg). Among 18 sulforaphane and related compounds synthesized (6 amines, 6 isothiocyanates, and 6 nitriles), 2 amines, 6 isothiocyanates, and 1 nitrile exhibited >5 cm inhibitory zones for H. pylori strain. The results indicate that broccoli sprouts can be an excellent food source for medicinal substances.

New pharmacokinetic in vitro model for studies of antibiotic activity against intracellular microorganisms.

The capacity for intracellular growth is an important survival strategy for a large group of common pathogens. Helicobacter pylori, the etiological agent for gastritis and duodenal ulcer, has been shown by both in vivo and in vitro studies to have the capacity to invade epithelial cells. In vitro models are used to study the effect of antibiotics on microoganisms. Most investigations are performed in broth culture or on agar plates, but kinetic models for bacteria in broth have been described. We present a new, kinetic model adapted for intracellular pathogens. A glass chamber, with a metal rack fitting Falcon cell culture inserts, was connected to a pump by rubber tubes. Different tube diameters and pump speeds were evaluated, and the assay was designed to mimic the half-lives of the antibiotics in vivo, i.e., 11.5 h for azithromycin, 5 h for clarithromycin, and 1 h for amoxicillin. Monolayers of HEp-2 cells were grown in the inserts for 2 days, after which H. pylori (clinical strain 88-23), was added to the system. Internalization was allowed for 12 h, and extracellular H. pylori cells were eradicated with gentamicin. The inserts were moved to the glass chamber, containing medium with 12.5 mg of either amoxicillin or azithromycin per liter or 2.4 mg of clarithromycin per liter. This represents 12.5, 50, and 80 times the extracellular minimum bactericidal concentration value, respectively. Samples were taken at 0, 2, 4, 6, 8, and 24 h. The HEp-2 cells were lysed, and intracellular bacteria were counted by plating. Inserts with infected cells grown in drug-free medium were included as controls for each time interval. A 3-log10 reduction of H. pylori was achieved in the experiments with azithromycin, and a 4-log10 reduction was achieved in the clarithromycin experiments, while no intracellular effect was seen when amoxicillin was used. The antibiotic concentrations at the sampling intervals were 12.5, 3.1, 0.8, 0.2, 0.05, and 0 mg/liter for amoxicillin; 12.5, 11.5, 10, 9, 8, and 3 mg/liter for azithromycin; and 2.4, 1.8, 1.4, 1, 0.8, and 0 mg/liter for clarithromycin. This new model for pharmacokinetic studies provides a useful tool, with applications for a broad range of microorganisms.

Relevance of the ferret model of Helicobacter-induced gastritis to evaluation of antibacterial therapies.

OBJECTIVES: The goals of the study were 1) to evaluate the efficacy of clinically relevant antibacterial therapies in the ferret model of Helicobacter-induced gastritis and 2) to compare these results to the efficacy achieved clinically in humans. METHODS: Ferrets were inoculated with H. mustelae, and gastritis was allowed to develop. The double therapy of clarithromycin and omeprazole and the triple therapies of clarithromycin or amoxicillin with metronidazole and omeprazole were administered. Efficacy was evaluated by Helicobacter burden cultured from biopsy samples and by histopathological evaluation of Helicobacter burden and gastric inflammation with pylorus and fundus samples obtained 4 wk after the end of antibacterial therapy. RESULTS: Clarithromycin-based double and triple therapies significantly reduced Helicobacter burden and decreased gastric inflammation. Clarithromycin-based double therapy was more effective than amoxicillin-based triple therapy. Reduction of the length of clarithromycin therapy from 14 to 7 days decreased efficacy. Antibacterial therapies in the ferret did not produce eradication rates comparable to clinical results, even though the serum concentrations of clarithromycin in ferret were in excess of concentrations used in humans. Relapse of Helicobacter infection after the end of therapy occurred in some cases. CONCLUSIONS: Although the ferret model of Helicobacter gastric infection underestimated the clinical efficacy of antibacterial treatments in humans, the model was valuable for comparing the relative efficacy of antibacterial therapies.

Unique susceptibility of Helicobacter pylori to simethicone emulsifiers in alimentary therapeutic agents.

Helicobacter pylori is killed in vitro by polyoxyethylene acyl esters and ethers similar to simethicone emulsifiers in therapeutic antifoams. The MBC of these compounds for Helicobacter pylori was less than 20 micrograms/ml, while other gram-negative bacteria were unaffected by much higher concentrations of up to 50 mg/ml.