Antonella Deriu

Distribution of virulence genes in Aeromonas spp. isolated from Sardinian waters and from patients with diarrhoea

Aims: To characterize 46 isolates of different Aeromonas spp. strains (26 Aeromonas hydrophila, 13 Aeromonas sobria and 7 Aeromonas salmonicida) isolated from coastal water and clinical sources in Sardinia, Italy.

In vitro susceptibility of Vibrio spp. isolated from the environment

Bacteria of the genus Vibrio include harmless aquatic strains as well as strains capable of causing epidemics of cholera and human intestinal diseases. Some of these species may show resistance to different antibiotics including cefotaxime, tetracycline and chloramphenicol. The susceptibility to different antibiotics was tested using 40 Vibrio alginolyticus, eight V. parahaemolyticus and six V. vulnificus strains isolated in the coastal waters of Northern Sardinia (Italy). The frequency of resistance to beta-lactams was unexpectedly high. More than 80% of Vibrio isolates were resistant to ampicillin and 2.5% of V. alginolyticus were resistant to ceftazidime and cefotetan. Forty percent of V. alginolyticus and three V. vulnificus isolates gave a positive nitrocefin test. PCR was also performed using selected primers chosen for having common sequences of bla(TEM) and bla(SHV) genes.

Distribution of Vibrio cholerae virulence genes among different Vibrio species isolated in Sardinia, Italy

The members of the genus Vibrio include harmless aquatic strains as well as strains capable of causing epidemics of cholera. Diarrhoea caused by Vibrio cholerae is attributed to cholerae enterotoxin (CT) codified by the ctx operon and regulated by a number of virulence genes such as toxT, toxR and toxS. Fifty‐two Vibrio strains were isolated from different aquatic environments in and around Sardinia and searched by PCR for the presence of ctxA, zot, ace, toxR, toxS, toxT, tcpA and vpi virulence genes in the genomes of the isolates. The toxR operon was found in 27 Vibrio alginolyticus strains out of 42 analysed, in three out of four V. cholerae non‐O1 strains and in three Vibrio parahaemolyticus isolates. A positive amplification for the virulence pathogenic island (vpi) was produced by five V. alginolyticus strains. Finally, the ace expected amplification fragment was found in two V. alginolyticus isolates whereas the amplification with zot primers produced the expected fragment in one V. alginolyticus isolate. Differentiation of these strains with a PCR fingerprinting technique revealed no association between the presence of virulence genes and a particular fingerprinting pattern. Although most Vibrio species are considered non‐pathogenic or only potentially harmful to humans, the finding of V. cholerae virulence genes in other members of the genus Vibrio, and the recent reports of the creation and evolution of pandemic strains of V. cholerae, may give a new perspective to the significance of these results.

Antimicrobial activity of Inula helenium L. essential oil against Gram-positive and Gram-negative bacteria and Candida spp.

In this work we report results regarding the in vitro antimicrobial activity of Inula helenium L. dried root extracts obtained by stepwise supercritical fluid extraction (SFE) and by hydrodistillation (HD). Inula helenium L. (Compositae family) is a perennial plant widely occurring in Europe and East Asia. Its oil is one of the richest sources of sesquiterpenoid lactones, which have strong anthelminthic activity and have the potential to induce detoxifying enzymes. Inula helenium L. roots (C-040705130905) were purchased from Minardi (Bagnacavallo-Ravenna, Italy). Supercritical CO 2 extraction was performed in a laboratory apparatus equipped with a 400 cm3 extraction vessel operated in the single-pass mode of passing CO 2 through the fixed bed of charged vegetable particles. Extraction was carried out in a semibatch mode: batch charging of vegetable matter and continuous flow solvent. HD was performed for 4 h in a circulatory Clevenger-type apparatus up to exhaustion of the oil contained in the matrix, which was the same material as used in the SFE.

Extraction of Lantana camara essential oil by supercritical carbon dioxide: influence of the grinding and biological activity.

The aim of this study was to produce Lantana camara essential oil by SFE and to study the effect of matrix grinding on the yield and/or composition of the extract. Experiments were carried out on grinding matrices (G) and on not grinding matrices (NG). The extracts were analyzed by GC–MS. A comparison with the oil obtained by hydrodistillation is also given. Finally, the antibacterial and antifungal activity of the various extracts has been assayed.