BackgroundHelicobacter pylori forms biofilms on glass surfaces at the air-liquid interface in in vitro batch cultures; however, biofilms of H. pylori have not been well characterized. In the present study, we analyzed the ability of H. pylori strains to form biofilms and characterized the underlying mechanisms of H. pylori biofilm formation.ResultsStrain TK1402 showed strong biofilm forming ability relative to the other strains in Brucella broth supplemented with 7% FCS. The strong biofilm forming ability of TK1402 is reflected the relative thickness of the biofilms. In addition, outer membrane vesicles (OMV) were detected within the matrix of only the TK1402 biofilms. Biofilm formation was strongly correlated with the production of OMV in this strain. We further observed that strain TK1402 did not form thick biofilms in Brucella broth supplemented with 0.2% β-cyclodextrin. However, the addition of the OMV-fraction collected from TK1402 could enhance biofilm formation.ConclusionThe results suggested that OMV produced from TK1402 play an important role in biofilm formation in strain TK1402.

OC-108 is a useful alternative treatment for hemorrhoids.

The human gastric pathogen Helicobacter pylori forms biofilms in vitro and in vivo. The purpose of this study was to evaluate the effects of H. pylori biofilm formation in vitro on clarithromycin (CLR) susceptibility. CLR susceptibility of H. pylori intermediate (2-day) and mature (3-day) biofilms on glass coverslips was determined at concentrations from 0.03 to 0.5 µg/ml. H. pylori biofilm biomass was increased after treatment with CLR at minimum inhibitory concentration levels by up to 4-fold (2-day biofilm) and 16-fold (3-day biofilm). Minimum bactericidal concentrations of CLR against cells in a biofilm were higher (1.0 µg/ml) than that for planktonic cells (0.25 µg/ml). It was shown that the expression of efflux pump genes was significantly increased in biofilm cells. In addition, exposure of biofilms to CLR resulted in high level resistance generation compared to planktonic cells with increased resistance associated with the presence of a point mutation at either position 2142 or 2143 in the domain V loop of the 23S rRNA gene. These results demonstrate that H. pylori biofilm formation decreases the susceptibility to CLR and that H. pylori CLR resistance mutations are more frequently generated in biofilms than in planktonic cells.

Helicobacter pylori is associated with gastric disorders in humans and some experimental animals, and possesses the luxS/type 2 autoinducer (AI-2) system. The effects of a specific luxS mutation on the characteristics of H. pylori were examined. On 0?3 % agar medium, motility of H. pylori HPKY08 (luxS : : cat) was significantly lower than that of wild-type H. pylori TK1402. The luxS-complemented strain HPKY21 exhibited motility comparable to that of H. pylori TK1402. It was shown that the luxS/AI-2 system plays an important role in H. pylori motility. The luxS mutant exhibited a reduced infection rate relative to the wild-type parent strain TK1402 in a Mongolian gerbil model. At 3 months after oral inoculation, lower numbers of H. pylori were detected by semi-quantitative real-time reverse transcription PCR (qRT-PCR) in luxS " mutant-infected gerbils than in TK1402-infected gerbils. Gastric inflammation and increased antibody titre for H. pylori were observed in TK1402-infected gerbils only. INTRODUCTIONQuorum sensing (QS) is a cell-to-cell communication system that regulates bacterial phenotypes, including the expression of virulence factor genes. The signalling molecules are known as autoinducers (AIs), and when these molecules reach a critical threshold concentration within a bacterial population, a signal transduction cascade is triggered, and this forms the basis for alterations in gene expression (Fuqua et al., 1994). Many Gram-negative bacteria utilize N-acylhomoserine lactone molecules, AI-1, as signals, while Gram-positive bacteria actively export peptides as signalling molecules. There is a second signalling system involved in a wide range of bacterial species (Schauder et al., 2001), and this system is utilized by both Gram-positive and Gram-negative bacteria. The signalling molecule known as type 2 autoinducer (AI-2) is a furanosyl borate diester (Chen et al., 2002), and the enzyme responsible for its synthesis is encoded by the luxS gene (Surette & Bassler, 1999). The genomes of many bacterial species, notably Escherichia coli, Salmonella enterica serovar Typhimurium, Shigella flexneri, Proteus mirabilis, Vibrio cholerae, Vibrio vulnificus, Campylobacter jejuni, Porphyromonas gingivalis, Bacillus subtilis, Streptococcus pyogenes, Streptococcus mutans, Clostridium perfringens and Clostridium difficile, include luxS homologues. In several of these, luxS-related AI-2 signals are involved in bacterial characteristics such as biofilm formation (Balestrino et al., 2005;Blehert et al., 2003;Fong et al., 2001;Wen & Burne 2004), flagella and motility (Jeon et al., 2003;Schneider et al., 2002;Stroeher et al., 2003), type III secretion systems (Sperandio et al., 1999), toxin production (Ohtani et al., 2002) and virulence (Lyon et al., 2001; Parsonnet et al., 1991;Stroeher et al., 2003).Helicobacter pylori has been identified as the aetiological agent of chronic active gastritis, peptic ulcer disease (Blaser, 1992;Graham, 1989), gastric adenocarcinoma (Parsonnet et al., 1991) and mucosal-associated lymphoid t...

In this study, we investigated the correlation between the microbiological characteristics of Clostridium difficile clinical isolates and the recurrence of C. difficile-associated disease (CDAD). Twenty C. difficile isolates recovered from 20 single infection cases and 53 isolates from 20 recurrent cases were analyzed by pulsed-field gel electrophoresis (PFGE) and PCR ribotyping, and the cytotoxicity, antimicrobial susceptibility, and sporulation/germination rates of the isolates were examined. Recurrent cases were divided into relapse or reinfection cases by the results of C. difficile DNA typing. Among the 20 recurrent cases, 16 cases (80%) were identified to be relapse cases caused by the initial strain and the remaining 4 cases (20%) were identified to be reinfection cases caused by different strains. All 73 isolates were susceptible to both vancomycin and metronidazole, but resistance against clindamycin, ceftriaxone, erythromycin, and ciprofloxacin was found in 87.7%, 93.2%, 87.7%, and 100% of the isolates, respectively. No correlations between DNA typing group, cytotoxicity, and sporulation rate of isolates and infection status, i.e., single, relapse, or reinfection, were observed. However, the isolates recovered from relapse cases showed a significantly higher germination rate when incubated in medium lacking the germination stimulant sodium taurocholate. These results indicate that the germination ability of C. difficile may be a potential risk factor for the recurrence of CDAD.