S. Di Bartolomeo

Characterization of an Helicobacter pylori environmental strain

Aims:  To investigate the main genotypic virulence markers and the phenotypic features of an environmental Helicobacter pylori strain, named MDC1.

Liposome-induced exfoliation of graphite to few-layer graphene dispersion with antibacterial activity

Few-layer graphene aqueous dispersions are obtained by exploiting liposomes as effective exfoliating agents for graphite. Raman measurements evidence the presence of non-oxidized double layer graphene as well as amphiphilic phospholipid molecules organized in bilayers in the samples. TEM analyses confirmed that the obtained homogeneous graphene nanosheets are embedded in the liposomal bilayer. The as-prepared graphene aqueous dispersion is stable for days and demonstrates significant antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) strains, with a reduction in the growth of S. aureus and E. coli as high as 60 and 78%, respectively.

Helicobacter pylori isolated from stomach corpus and antrum: Comparison of DNA patterns

The genomic DNA of Helicobacter pylori was studied in strains isolated from two different sites of the stomach: the corpus and the antrum. 70 strains of H. pylori were found in 36 patients; 34 out of the 36 patients harboured the strain in both districts analysed. Restriction endonuclease analysis with Hae III and Hind III was used to compare the DNA patterns of strains isolated from the anatomical sites studied. Two pairs of DNA samples were not digested by these enzymes. 27 of the 32 pairs of the digested DNA appeared similar to each other. The analysis of chromosomal DNA in the remaining five pairs showed different electrophoretic patterns. These results indicate that the gastric mucosa can be colonized, at the same time, by strains of H. pylori with different genomic patterns, and this aspect can be important for epidemiological studies.

Biofilm formation and modulation of lux S and rpo D expression by Helicobacter pylori

Bacteria often choose a sessile biofilm lifestyle as a strategy to overcome environmental stress. In this study, we describe biofilm formation by Helicobacter pylori on a polystyrene surface, evaluating the viability and the morphological dynamics of bacterial cells during multicellular aggregate development. Moreover, we investigate expression of the lux S and rpo D genes, which are involved in biofilm formation. Two clinically susceptible and resistant strains of H. pylori were analyzed, as well as H. pylori ATCC 43629 for reference. The dominant form of expression, clustered bacterial cells arranged in an abundant matrix, was recorded after 2 days of incubation without shaking. Coccoid (spherical) cells with a “wrinkled” aspect presented the prevalent morphology (59.26%) among cells in the biofilm structure as observed by scanning electron microscopy. In aged H. pylori cultures, death occurred in single cells or cells grouped into microcolonies in which degenerated bacteria were localized inside the aggregates. The expression of lux S and rpo D genes among the sessile bacterial population reached a maximum after 2 days, with a significant reduction at subsequent time-points. No differences in gene expression and biofilm formation were recorded in the three evaluated strains. The morphological fickleness expressed in the life cycle by H. pylori strains emphasizes the bacteriums ability to overcome environmental stress, balancing its spread both outside and inside the host.

Helicobacter pylori biofilm: a protective environment for bacterial recombination.

The aim of this work was to investigate the interaction between two Helicobacter pylori strains in promoting genetic transfer, when grown in the biofilm mode.

In vitro activity of Aloe vera inner gel against Helicobacter pylori strains

Aloe barbadensis Miller (Aloe vera) is a herbal remedy widely used for a variety of illnesses; A. vera leaf extracts have been promoted for detoxification, cure constipation, help flush out toxins and wastes from the body, promote digestion and are used in the treatment of peptic ulcer for cytoprotective action. The aim of this study was to evaluate the antibacterial activity of A. vera inner gel against both susceptible and resistant Helicobacter pylori strains isolated in Abruzzo region, Italy. The inner gel of leaves of a 5‐year‐old plant of A. vera was extracted, homogenized and tested from 800 to 1·56 mg ml−1 against 14 clinical strains and one reference strain of H. pylori using the broth microdilution methodology. Furthermore, the sample of A. vera was investigated for the chemical fingerprint of anthraquinones. The inhibitory concentrations of A. vera inner gel were similar to the bactericidal ones, with values ranging from 6·25 to 800 mg ml−1. Fifty per cent of the detected strains, independently of their susceptibility profile, were inhibited in their growth at 100 mg ml−1. Aloe vera inner gel expresses antibacterial properties against H. pylori and, therefore, in combination with antibiotics, could represent a novel strategy for the treatment of the infection of H. pylori, especially in cases of multiresistance.

Effect of 2‐hydroxyethyl methacrylate on Streptococcus spp. biofilms

Aims:  The effect of different concentrations of 2‐hydroxyethyl methacrylate (HEMA) was evaluated on biofilm formation and preformed biofilm of Streptococcus mitis, Streptococcus mutans and Streptococcus oralis, alone or combined to each other.

In vitro activity of Aloe vera inner gel against microorganisms grown in planktonic and sessile phases.

The failure of traditional antimicrobial treatments is becoming a worldwide problem. The use of Aloe vera is of particular interest for its role as curative agent and its efficacy in complementary therapies for a variety of illnesses. This study evaluated the antimicrobial activity of A. vera inner gel against a panel of microorganisms, Gram-positive and -negative bacteria, and Candida albicans. In addition to A. vera inner gel being used in the treatment of peptic ulcers, in dermatological treatments, and wound healing, it was also tested on the sessile phase of clinical Helicobacter pylori strains (including multi-drug-resistant strains) and on planktonic and sessile phase of Staphylococcus aureus/Pseudomonas aeruginosa clinical isolates from venous leg ulcers. A. vera inner gel expresses its prevalent activity against Gram-negative bacteria and C. albicans in respect to Gram-positive bacteria. The results of the A. vera antibiofilm activity showed a decrease of the produced biomass in a concentration-dependent-way, in each analyzed microorganism. The data obtained show that A. vera inner gel has both an antimicrobial and antibiofilm activity suggesting its potential use for the treatment of microbial infections, in particular for H. pylori gastric infection, especially in case of multi-drug-resistance, as well as for an effective wound dressing.