Class I integrons were detected in 40.8% (40/98) of Pseudomonas aeruginosa strains and 52.8% (56/106) of Acinetobacter baumannii strains in the Nanjing area of China, including several cassette arrays not previously reported.The rapid dissemination of antibiotic resistance genes among bacterial isolates is an increasing problem in infectious disease. Recent studies have shown that a conserved DNA sequence, integron, may be carried on these episomal genetic structures (12,14). Integrons possess two conserved segments separated by a variable region that includes integrated cassettes, which often include antibiotic resistance genes (11). Many resistance genes are present as gene cassettes within integrons, which may themselves be located on transmissible plasmids and transposons (11). In China, resistance to various antibiotics is common in clinical isolates, often more so than in Western countries, especially among Pseudomonas aeruginosa and Acinetobacter baumannii isolates (7,8,16). However, the frequencies, characteristics, and roles of integrons and gene cassettes in the two species have not yet been investigated in a large-scale study.In order to study the roles of gene cassettes in the two species, we obtained 98 P. aeruginosa isolates and 106 Acinetobacter sp. isolates from four general hospitals in the Nanjing area of China during June 2003 and June 2005. The strains were randomly obtained from a variety of clinical specimens from diverse units of the four hospitals. All bacterial strains were identified by the analytical profile index procedure (API-20NE system; bioMerieux, France). Susceptibility to antimicrobial agents was tested by the disk diffusion method on Mueller-Hinton agar plates, according to Clinical and Laboratory Standards Institute guidelines (2). DNA used for PCR was prepared as described previously (9). All isolates were screened for integrons by PCR using degenerate primers hep35 (5Ј TGCGGGTYAARGATBTKGATTT 3Ј) and hep36 (5Ј CARCACATGCGTRTARAT 3Ј) and HinfI restriction analysis of the integrase gene product (18). Class I integron

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Helicobacter suis has a greater tendency to induce gastric mucosa-associated lymphoid tissue lymphoma compared with other Helicobacter species in humans and animals. Saccharomyces boulardii has been established as an adjunct to H. pylori eradication treatment, but the effect of S. boulardii administration alone on Helicobacter infection remains unclear. Here, we found that S. boulardii administration effectively decreased the bacterial load of H. suis and inhibited the formation of lymphoid follicles in the stomach post-infection. The levels of H. suis-specific immunoglobulin A (IgA) and secretory IgA in the gastric juice and small intestinal secretions and the production of mouse β-defensin-3 in the small intestinal secretions were significantly increased by S. boulardii administration at 12 weeks after H. suis infection. In addition, feeding with S. boulardii inhibited the expression of inflammatory cytokines and lymphoid follicle formation-related factors after H. suis infection. These results suggested that S. boulardii may be useful for the prevention and treatment of Helicobacter infection-related diseases in humans.