Adherence of Aeromonas hydrophila strains to human enterocyte-like cells pre-infected with rotavirus.

INTRODUCTION: The interest grown in these years about emerging pathogens in the onset of intestinal disease showed that the pathogenic mechanism is a multifactorial event. Our objective was to evaluate the role of co-infection with rotavirus in the expression of Aeromonas spp adhesiveness. METHODS: The rate of co-infection involves contact of Caco-2 cells with the virus, followed by adsorption for 1 and 2 hours. Aliquots of bacterial suspensions were added to tissue-culture plates. After infection, cell monolayers were lysed; serially diluted lysates were plated to determine the number of bound bacteria by performing colony forming units (CFU) counts. RESULTS: Non-adhesive strains were not subject to variations resulting from co-infection, while those who had medium or high adhesiveness gave rise to an increase of the same. DISCUSSION: Infection with rotavirus promotes the Aeromonas ability to adhere to Caco-2 cells and this effect depends on the duration of infection and on the starting adhesiveness of bacteria strain.

Seroprevalence study on the diffusion of the West Nile virus among blood donors, healthcare workers, jockeys, grooms and fowlers, veterinary surgeons and hunters in Messina (Italy).

INTRODUCTION: West Nile virus (WNV) is a mosquito-transmitted flavivirus widely distributed in Africa, Middle East, Asia, Southern Europe and in 1999 was first identified in the United States as a cause of disease in New York City. It mainly circulates among birds, but can infect many species of mammals. Epidemics can occur in rural as well as urban areas. METHODS: 1,280 sera were collected during 2006 from 80 stable workers, as jockey and grooms, 100 fowlers, 500 blood donors, 600 healthcare workers, 100 veterinary surgeons and 100 hunters in the Messina province to evaluate the prevalence of the WNV infection, by ELISA test, in relation to risk exposure or not. RESULTS: None of the 1280 subjects examined has shown positive for antibodies anti WN virus. CONCLUSION: Among the strategies of control and surveillance, finally, in our opinion, are and will be indispensable the programs of continuous antibody survey in all the risk categories and in the general population in order to succeed to preview which effects could have the presence of infections from WNV, also imported from other zones where the virus is constantly present, in future and which it could be the impact of geographic factors on the epidemic spread of the disease.

[Effects of "host factor" bile on adaptability and virulence of Vibrios, foodborne potential pathogenic agents]. / Effetti della bile come "fattore-ospite" su adattamento e virulenza di potenziali agenti patogeni a trasmissione alimentare appartenenti al genere Vibrio.

In order to improve the knowledge of host/pathogenic agent interaction and to obtain a more careful estimation of risk related to ingestion of food contaminated by Vibrio spp., the effects of bile extracts have been studied. The growth of one V. fluvialis, two V. alginolyticus, and three V. parahaemolyticus strains, isolated from mollusks and crustaceans, has been determined to evaluate their adaptability to intestinal environment. Moreover, the expression of virulence factors responsible for the colonization, as bacterial "swarming mobility", biofilm production, adherence on epithelial cells and hydrophobicity, has been evaluated. Using a bile concentration of 1.5%, all examined strains showed a constant inhibitory effect, quite moderate in the first growth phases. Bile increased the "swarming mobility" and biofilm production; also the adherence was favored, but only after adaptation and during the early logarithmic phase. The decreased hydrophobicity could explain the reduction of adherence during the stationary phase. Studying the phenotypic expression of virulence factors in "minor vibrios" in the presence of bile, it was possible to extend the knowledge about their pathogenetic mechanisms owing to the ingestion of contaminated food. That permits a more careful estimation of risk related to the contamination, considering the high frequency of isolation of these species in some seafood.

Effect of growth conditions on extracellular products (ECPs) of Aeromonas hydrophila.

Owing to the significant role in gastrointestinal illness of A. hydrophila, frequently detected in various raw and ready-to eat foods, its pathogenetic mechanisms are particularly studied. In this paper we report the results obtained studying in vitro the effect of O2 tension and inoculum age on the extra cellular products (ECPs) of seven strains food-borne isolated and cultured at 37 degrees. The considered factors influenced markedly bacterial growth as well as ECPs production and the more notable differences were detected among 15 hours old strains let grown slowly shaking (15SH), that showed the highest bacterial yield, and 24 h old strains cultured statically (24ST), whose haemolysin and cytotoxin production was favoured. Wilcoxon test shows as, in these latter conditions, the strains needed short time to adapt the haemolysin and cytotoxin production. The oxygen tension reduction, extending the replication time, induces the bacterial metabolism toward secondary products, as verified by Spearman test applied to ECPs indexes. The increased production per cell of virulence-associated factors could be responsible of gastrointestinal disorders caused by food-borne A. hydrophila strains, even without a massive gut colonization, especially when immunocompromised individuals ingest contaminated foods.

Evaluation of antiherpesvirus-1 and genotoxic activities of Helichrysum italicum extract.

The antiherpes virus-1 and genotoxic activities of diethyl ether extract from flowering tops of Helichrysum italicum (Compositae) were investigated. The extract showed significant antiviral activity at concentrations ranging from 400 to 100 microg/ml. This activity was not due to cytotoxic effect of the extract since Vero cells exhibited altered morphology or growth characteristics indicative of cytotoxic effects at higher concentration (800 microg/ml). Moreover H. italicum extract showed no DNA-damaging activity at concentrations up to 2000 microg/disk.

Is diabetes mellitus a risk factor for HCV infection?

The aim of this study was to investigate whether or not the diabetes mellitus may be considered a risk factor for the HCV infection. The HCV seroprevalence was evaluated in 254 diabetic subjects, whose anamnestic data and risk factors are known, in comparison to 223 first-time blood donors, carefully age- and gender-matched. The statistical analysis showed that the studied groups belonged to the same population (Mann-Whitney U test) and that there were no significant differences between cases and controls as regards HCV prevalence (Yates corrected chi 2 test). The obtained data underline the importance of the control group selection, especially in the studies considering age-related pathologies. The authors disprove type 2 diabetes as a risk factor for the HCV infection and consider that this is a valid hypothesis only when the hepatitis C was unknown and not adequate prevention was used.

Virulence factors in Vibrios and Aeromonads isolated from seafood.

Thirty-one isolates from seafood, identified as Aeromonas hydrophila (7), Aeromonas caviae (11), Vibrio parahaemolyticus (3), Vibrio fluvialis (5), Vibrio alginolytictus (3), Vibrio metschnikovii (1) and Vibrio damsela (1), were tested for possible virulence factors including extracellular hydrolytic enzymes, haemolysins, cytotoxins (VERO and HEp-2 cells) and adherence ability (HEp-2 cells). All the A. hydrophila strains were beta-haemolytic and produced cytotoxins as well as one strain of V. fluvialis. A. hydrophila and A. caviae strains, frequently adhesive, showed both aggregative and diffusive patterns, while five Vibrio strains only (three V. fluvialis, one V. parahaemolyticus and one V. alginolyticus) were adhesive with an aggregative pattern.

[Isolation of Listeria spp., Aeromonas spp., and Vibrio spp. from seafood products]. / Isolamento in prodotti ittici di Listeria spp., Aeromonas spp. e Vibrio spp.

Forty-one strains of Listeria, Aeromonas and Vibrio have been isolated in 71 samples of seafood, both raw and ready to eat and frozen. L. monocytogenes, detected by PCR also, is found in the smoked salmon only. Aeromonas spp. and Vibrio spp. are isolated in the raw products (shrimps and shellfish). No relationship is found between the presence of such microrganisms and the common indicator bacteria. Finally, the health hazard related to strong contamination and the need to diversify the food safety assurance programmes, for the various products, are underlined.

Direct viable count as test for toxicity assessment: the effects of four metals on a Salmonella enteritidis strain.

The toxicity of synthetic sewage containing increasing concentrations of arsenic (.125, .25, .5, 1.0 mg L-1), cadmium (.02, .05, .1, .2 mg L-1), lead (.2, .5, 1.0, 2.0 mg L-1) and nickel (.5, 1.0, 2.0, 4.0 mg L-1) has been investigated by determining the total direct count (TDC) and the direct viable count (DVC) of Salmonella enteritidis by means of an immunofluorescence technique (IFA). This has been done in order to evaluate the possibility of using the IFA technique to estimate the toxicity of complex effluents. Arsenic, cadmium and nickel produced a concentration-dependent reduction in the number of viable bacterial cells. This was more clear when the viable bacterial cells were considered than when only the culturable part was used. Lead did not show a concentration-dependent and reproducible effect. At the highest concentrations allowed by the Italian wastewater regulations, lead, cadmium, arsenic and nickel reduced the viable/total bacterial cells ratio to 74.5%, 68.5%, 28.4% and 6.9%, respectively. The toxic effects of the metals were also tested using the standard Microtox assay.

Effect of metal mixtures on Salmonella enteritidis viability in synthetic sewage.

We sought to determine the effect of 26 multiple metals solutions, containing Cd, Pb, As and/or Ni, on the viability of Salmonella enteritidis. We used the direct viable count effected by immunofluorescence technique (IFA-DVC) in comparison with the culturable cell count. The metals concentrations were prepared considering the single as well as the overall limits provided by Italian regulation on the water pollution. The mixtures containing nickel showed always toxicity more elevated than other metal solutions tested. Thus we consider too high the nickel law limit. The interactions among the elements, causing generally toxicity decrease, are very well assessable by IFA-DVC test. This method permits to calculate the lethal concentrations of toxicants on bacteria that play a pivotal role on the ecosystem components.

[Water quality and microbiological status of the distribution system: traditional parameters and emerging parameters]. / Qualità dell'acqua e stato microbiologico alla distribuzione: parametri tradizionali e parametri emergenti.

Most pollution of drinking water is caused by inadequacy of the uptake and distribution systems, by insufficient upkeep of the sewage system and by defects or breaks in the disinfection processes. This may be the cause of waterborne epidemic outbreaks and therefore it is necessary carry out routine controls by simple and rapid tests for the detection of intestinal organisms. In the light of minor hepatitis A epidemics occurred in the town of Messina, we have carried out a study to determine the drinking water quality. To this end, in addition to the traditional tests recommended by CEE and required by the 8/2/1985 DPCM (37 degrees C and 20 degrees C viable count, total and faecal coliforms and faecal streptococci), we have carried out P. aeruginosa, coliphages and gram-negative endotoxins tests, in 74 water samples drawn on way in and way out of the tanks and along the piping system. Only 12.5% of the sixteen water samples drawn on way in (before disinfection system) was in compliance with the law. 75% of these samples showed positivity for faecal streptococci. The water quality was lower in the fourteen water samples drawn on way out of the tanks (7.1% was in compliance with the law). The percent of positivity along the piping system for total and faecal coliforms and for faecal streptococci was 34.1, 15.9 and 59.1 respectively. Coliphages were always absent. P. aeruginosa was almost always present in way in water (93.7%). Moreover this microorganism was recovered in 85.7% of the samples drawn on the way out and in 77.3% along the piping system. In the same drawing places endotoxins were present at high percentage (100%, 85.7% and 90.9%). These values come from high test sensitivity and poor water quality. Finally we have pointed out the importance of all the parameters examined. The significance of coliform bacteria is known, but we consider very important, as organisms indicative of pollution, the enterococci, since they P. aeruginosa may survive long time in fresh water though it is not autoctone, but, in general, of faecal origin. Several soluble antigens of this microorganism as well as enterococci show positive LAL tests (1-5-6). The endotoxin content in fresh water reflects the degree of bacterial contamination. We believe, therefore, it is needed to fix an upper limit to endotoxins in drinking water. Coliphages concentrations could be correlated with enteric virus concentrations but the ratio of coliforms to coliphages is about 100:1. Therefore this indicator of viral pollution is helpful only for highly polluted surface waters.

[Effect of the carbon/nitrogen ratio on the antibiotic activity of prodigiosin]. / Influenza del rapporto carbonio azoto sull'attività' antibiotica della prodigiosina.

The antibacterical activity of prodigiosin varies according to the C/N ratio in the cultural media for S. marcescens. In organic media, as nutrient agar, peptone or soytone, the optimal ratio lies between 4 and 5, and higher values are required for "mineral media" where the nitrogen source is essentially an ammonium salt. The separate C source would be probably used as "acetate source" for the synthesis of the terminal alkylpyrrole.

[Comparison between the way of intravenous administration of flagellin from Salmonella typhosa to the margial vein in the ear and into the mesenteric superior vein. Preliminary note]. / Confronto tra la via di introduzione endovenosa di "flagellina" della Salmonella typhosa nella vena marginale dell'orecchio e nella vena mesenterica superiore. Nota preliminare

Rabbits receiving three injections of PFA intravenously in ear, after that first treatment gave a weak antibody response, after the second one a rapid and copious increase of agglutination titre; the third injection induced a very small increase. In rabbits injected with PFA in superior mesenteric vein the first injection produced a little effect, the second induced a little effect too; the third injection performed in auricular vein, gave a substancial rapid and copious antibody response. This behaviour is similar to that obtained after the second injection in the first set of experiments. The PFA injected two times in mesenteric vein caused certainly a massive phagocytosis of antigen by Kupffer cells. Nevertheless this copious phagocytosis can exercise only an action of "priming", not a response of secondary type. For this purpose it is necessary an injection in the ear vein to provoke a direct intervention of lymphonodal reticular phagocytes. The phenomenon can be related to the proteic nature of the antigen.