[Show abstract][Hide abstract] ABSTRACT: With this study, 28 pools of snails of the genus Helix, respectively Helix aspersa (n=24) and Helix vermiculata (n=4) were analysed. They were taken from snail farming and stores. The snails were from Sardinia, other regions of Italy, and from abroad. All the samples were examined as pool looking for these microbiological target: Salmonella spp., Listeria monocytogenes, Escherichia coli O157, Clostridium perfringens, Norovirus and Hepatitis A Virus (HAV). In the same pools, the concentration of cadmium and lead by inductively coupled plasma mass spectrometry was also determined. The levels of these heavy metals were quite high, especially for cadmium. Two samples were positive for Salmonella spp., while no sample was positive for Escherichia coli O157, HAV and Norovirus. Two samples were positive for Clostridium perfringens and 8 for Listeria monocytogenes. The microrganisms related to Listeria monocytogenes were identified using biochemical techniques, then serotyped and gene sequenced by multiple loci sequence typing technique. Furthermore, antimicrobial restistence was tested on the same samples.
Full-text · Article · Apr 2014 · Italian Journal of Food Safety
[Show abstract][Hide abstract] ABSTRACT: In this study, the antibiotic resistance pattern and the presence of genes encoding several virulence factors in 91 Enterococcus faecalis strains isolated from different human clinical sources in Sardinia were investigated. Genotypic determination of virulence genes (gelE, esp, agg, ace, cylA,B,M,L(L),L(S), efaA, fsrB) was carried out by PCR. The production of gelatinase and haemolytic activity were also determined. Antimicrobial susceptibility tests were performed by an automated microdilution test (Vitek). The strains examined in this study contained at least one and up to as many as all virulence genes investigated. Examining the distribution of these factors in the different groups of clinical strains, we found that all but one virulence determinant were detected more frequently among urinary isolates. The detection of some factors by PCR did not always correlate with its phenotypic expression. Antibiotic susceptibilities among the Enterococcus faecalis strains investigated in our study were typical for the species, with expected levels of acquired resistance. Faecal isolates had the highest percentage of resistance, especially to high level-gentamicin, ciprofloxacin and norfloxacin. In summary, a wide variety of genes encoding virulence factors have been detected among our clinical Enterococcus faecalis strains, and those isolated from UTI were characterized by a higher virulence potency compared with strains from other clinical sources. Silent virulence genes (cyl or gelE) were frequently detected, therefore both the genotypic and phenotypic assays seem necessary for a better characterization of the strains. Our results may serve as a basis for additional surveillance studies of infections caused by this microorganism.
Full-text · Article · Mar 2010 · Journal of preventive medicine and hygiene
[Show abstract][Hide abstract] ABSTRACT: Two hundred sixty three Candida isolates were obtained from specimens of patients hospitalized in a Intensive Care Unit. Candida albicans was the predominant species, followed by C. tropicalis, C. krusei, C. glabrata e C. parapsilosis. For C. albicans isolates, amphotericin B was the more efficient antifungal (2.3% of resistant strains), while voriconazole was the more efficient for C. krusei and C. glabrata, known for their lower susceptibility to fluconazole. RAPD-PCR technique with CDU primer was used for the molecular characterization of 48 C. albicans strains isolated from 10 patients. Genetic similarity at 90% level was observed for some Candida strains isolated from the same patient, indicating a possible colonization from the original strain. Moreover the high similarity coefficient observed between isolates from different patients may indicate an exogenous colonization originating from hospital-endemic strains or inadequate manipulation by health care workers.
No preview · Article · Jan 2010 · Annali di igiene: medicina preventiva e di comunità
[Show abstract][Hide abstract] ABSTRACT: Fourteen Lactobacillus strains, isolated from artisanal Fiore Sardo cheese that were able to grow at pH 2.0 and in the presence of 0.3% bile, were evaluated for some functional characteristics relevant to their use as probiotic cultures. Most of the strains survived the conditions of the gastro-intestinal tract, and two also exhibited bile salt hydrolase activity. The levels of aggregation activity were similar in the strains tested. The most active strains also had high hydrophobicity levels. Most of the strains showed antagonistic activity against the indicator strains L. monocytogenes ATCC 7644, E. coli ATCC 35150 and Y. enterocolitica ATCC 9610. High frequencies of antimicrobial resistance were observed towards aminoglycosides, glycopeptides, sulfamethoxazolo and trimethoprim. Six strains showed a number of in vitro properties that would make them suitable for use as adjunct cultures in the development of potentially probiotic cheese.
No preview · Article · Jan 2008 · Italian Journal of Food Science
[Show abstract][Hide abstract] ABSTRACT: This work evaluated the effect of adjunct autochthonous cultures on the chemical, microbiological and sensory characteristics of Fiore Sardo cheese during ripening. A total of twelve batches of cheeses were manufactured according to the technical Disciplinary of Fiore Sardo cheese, with and without different combinations of autochthonous strains isolated from the native microflora of artisanal Fiore Sardo. There were no significant differences in the cheese compositional parameters between experimental and control cheeses, but the addition of cultures led to a statistically significant decrease in pH values in experimental cheeses. The evolution of total mesophilic bacteria, total coliforms and lactic acid bacteria were significantly influenced by the addition of autochthonous cultures in most of the experimental cheeses. As for sensory characteristics, all the experimental cheeses reported significantly higher scores especially for shape, texture, interior openings, taste and aftertaste. This study demonstrated the beneficial effect of the addition of selected autochthonous cultures in accelerating the disappearance of undesirable flora and improving the typical sensory characteristics of the cheese, and confirmed the importance of ewes' milk as a source of technologically interesting strains that could be used to ensure a higher quality of artisanal cheese productions.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to assess the chemical and microbial characteristics of 12 batches of artisanal Fiore Sardo, a protected designation of origin (PDO) hard cheese made from raw ewe's milk without addition of starters, during maturation. High standard deviations were observed for moisture percentage, total solids percentage and NaCl percentage content, possibly owing to differences in manufacturing processes and/or milk composition. Total mesophilic bacteria varied between 10 log10 cfu/g in 48-h-old cheese samples and 3 log10 cfu/g in 9-month-old samples. Total coliforms and staphylococci showed the highest counts at 48 h of ripening then decreased significantly, dropping to levels below 2 log10 cfu/g at 3 months of maturation. Lactic acid bacteria and enterococci were the dominant micro-organisms throughout maturation. They were mainly represented by the species Lactococcus lactis ssp. lactis, Enterococcus faecium, Lactobacillus plantarum and Lactobacillus casei group. Low levels of yeasts were detected throughout the maturation period of the cheese. Debaryomyces hansenii and Kluyveromyces lactis var. lactis were the prevalent yeast species isolated.
Full-text · Article · Jul 2006 · International Journal of Dairy Technology
[Show abstract][Hide abstract] ABSTRACT: A total of 118 enterococcal strains isolated from artisanal Fiore Sardo cheese were characterized technologically and genetically. The presence of potential virulence factors was also investigated. Strains were classified as Ec. faecium (84 strains), Ec. durans (24 strains) and Ec. faecalis (10 strains). RAPD-PCR analysis with two different primers (M13 and XD9) confirmed species identification and proved useful for the detection of interstrain variations, especially among Ec. faecium isolates. Most strains could hydrolyse casein and had weak acidifying activity in milk. None of the isolates produced lipolytic reactions. Gelatinase activity was observed in two strains of Ec. faecalis and one strain of Ec. durans. beta-Haemolysis on horses' blood was never detected in any of the strains, independently of species. Most strains produced tyramine from tyrosine but none decarboxylated lysine, histidine or ornithine. Overall, a wide spectrum of resistance was observed. Almost all strains were resistant to the aminoglycosides, gentamycin, kanamycin, streptomycin, neomycin, and to the semisynthetic penicillin, oxacillin, but resistance to vancomycin was not widespread among our strains: only one Ec. faecium and one Ec. durans strain were found to be vancomycin resistant. Our results show a certain diversity in technological traits of the enterococcal strains isolated from artisanal Fiore Sardo, together with a low incidence of some potentially pathogenic traits of health concern.