Production of a metallo-β-lactamase activity was detected in a carbapenem-resistant Pseudomonas aeruginosa clinical isolate (isolate VR-143/97) from an Italian inpatient at the Verona University Hospital (northern Italy). The metallo-β-lactamase determinant was isolated from a genomic library of VR-143/97, constructed in an Escherichia coli plasmid vector, by screening for clones with reduced susceptibility to imipenem. Sequencing of the cloned gene revealed that it encoded a new class B β-lactamase that was named VIM-1. At the sequence level VIM-1 was rather divergent from the other class B enzymes (16.4 to 38.7% identity), overall being more similar to members of subclass B1 including the β-lactamase II of Bacillus cereus (Bc-II), the Bacteroides fragilis CcrA, the Chryseobacterium meningosepticum BlaB, and the cassette-encoded IMP-1 enzymes. Among these, VIM-1 showed the highest degree of similarity to Bc-II. Similarly to bla IMP,bla VIM was also found to be carried on a gene cassette inserted into a class 1 integron. Thebla VIM-containing integron was located on the chromosome of P. aeruginosa VR-143/97, and the metallo-β-lactamase-encoding determinant was not transferable toE. coli by conjugation. Expression of the integron-bornebla VIM gene in E. coli resulted in a significant decrease in susceptibility to a broad array of β-lactams (ampicillin, carbenicillin, piperacillin, mezlocillin, cefotaxime, cefoxitin, ceftazidime, cefoperazone, cefepime, and carbapenems), revealing a very broad substrate specificity of the VIM-1 enzyme.

A total of 8 Pseudomonas aeruginosa isolates was collected from 7 different patients in different wards of the University Hospital of Verona, Italy, from February 1997 to February 1998. The high level of resistance to carbapenems (imipenem minimum inhibitory concentration was always >128 microg/mL) and other broad-spectrum beta-lactams and the rate of imipenem hydrolysis and its inhibition by ethylenediamine-tetra-acetic acid were all suggestive of production of a carbapenem-hydrolyzing metallo-beta-lactamase. A specific DNA probe derived from the recently cloned bla(VIM-1) gene hybridized to all the isolates. A genomic DNA fingerprinting profile revealed clonal relatedness for 7 of 8 isolates. A description of this hospital outbreak is reported, the occurrence of which confirms that proliferation of metallo-beta-lactamase-producing strains multiply resistant to beta-lactams is already a reality outside Japan. These findings emphasize the need for early recognition of similar isolates.

No abstract

Helicobacter pylori is a gram-negative bacterium that colonizes the human gastric mucosa causing gastritis and peptic ulcer and increasing the risk of gastric cancer. The efficacy of current antibiotic-based therapies can be limited by problems of patient compliance and increasing antibiotic resistance; the vaccine approach can overcome these limits. The present study describes the therapeutic vaccination of experimentally H. pyloriinfected beagle dogs, an animal model that reproduces several aspects of the human infection with H. pylori. The vaccine consisted of three recombinant H. pylori antigens, CagA, VacA, and NAP, formulated at different doses (10, 25, or 50 g each) with alum and administered intramuscularly either weekly or monthly. No adverse effects were observed after vaccination and a good immunoglobulin G response was generated against each of the three antigens. Bacterial colonization and gastritis were decreased after the completion of the vaccination cycle, especially in the case of the monthly immunization schedule. In conclusion, therapeutic vaccination in the beagle dog model was safe and immunogenic and was able to limit H. pylori colonization and the related gastric pathology.Helicobacter pylori is a spiral-shaped, gram-negative bacterium that infects the stomach of Ͼ50% of the population worldwide, with higher prevalence in the developing countries. H. pylori induces chronic inflammation of the stomach mucosa, causing chronic gastritis and peptic ulcer (9, 33); moreover, H. pylori infection is related to gastric mucosa-associated lymphoid tissue lymphoma (4) and to an increased risk of gastric cancer (36), as also proved in animal models (13,38).Current therapies, based on one antisecretory agent plus antibiotics, although effective in 80 to 90% of cases, face problems of patient compliance, increasing antibiotic resistance, and possible recurrence or reinfection; in spite of continuous effort to improve these treatments, no major breakthroughs have been achieved in the most recent years (30).To overcome the limits of antibiotic-based therapies, the vaccine approach has been undertaken since the last decade, leading us to identify some relevant bacterial antigens as candidates for vaccines (2). On the other hand, animal models of H. pylori infection have been developed to study the interaction between the bacterium and the host, the mechanisms of immune response to either infection or vaccination, and to determine the efficacy of both prophylactic and therapeutic vaccination (2,17,26,34). Among these animal models, that of the beagle dog reproduces several aspects of the human infection with H. pylori. In fact, in the beagle dog model, intragastric administration of H. pylori results in a long-term chronic infection, characterized by gastritis, epithelial alterations, superficial erosions, and the appearance of macroscopic follicles in the gastric mucosa, mainly in the antral region of the stomach (28,29).Most of the examples of vaccination against H. pylori in animal models reported in the...

AIM:To investigate whether red wine and green tea could exert anti-H pylori or anti-VacA activity in vivo in a mouse model of experimental infection. METHODS:Ethanol-free red wine and green tea concentrates were administered orally as a mixture of the two beverages to H pylori infected mice, or separately to VacA-treated mice. Gastric colonization and gastric inflammation were quantified by microbiological, histopathological, and immunohistochemical analyses. RESULTS:In H pylori -infected mice, the red wine and green tea mixture significantly prevented gastritis and limited the localization of bacteria and VacA to the surface of the gastric epithelium. Similarly, both beverages significantly prevented gastric epithelium damage in VacA-treated mice; green tea, but not red wine, also altered the VacA localization in the gastric epithelium. CONCLUSION:Red wine and green tea are able to prevent H pylori -induced gastric epithelium damage, possibly involving VacA inhibition. This observation s u p p o r t s t h e p o s s i b l e r e l e va n c e o f d i e t o n t h e pathological outcome of H pylori infection.