Antimicrobial susceptibility of environmental Staphylococcus aureus strains isolated from a pigeon slaughterhouse in Italy

Abstract No information is available concerning the antimicrobial susceptibility of Staphylococcus aureus isolated from pigeon slaughterhouses. In the present study, 59 staphylococcal strains isolated from a pigeon slaughterhouse in central Italy were compared according to their antibiotic resistance. On the basis of cultural and biochemical properties, all isolates could be identified as S. aureus. The strains were checked for the productions of enterotoxins A, B, C, D by reversed passive latex agglutination. Resistance to 26 antibiotics was also determined paying particular attention to resistance to those antimicrobial agents frequently used in human medicine and in poultry breeding. Only one strain was positive for the production of enterotoxins type C and D. It was isolated from the evisceration tube after slaughtering. Enterotoxin B was produced by 2 strains isolated from the eyebrows and conjunctivas of the worker operating the crop rinsing tube. As to the susceptibility to antibiotics, all strains were sensitive to amoxicillin/clavulanic acid, bacitracin, cephalothin, fusidic acid, gentamicin, kanamycin, linezolid, oxacillin, quinupristin/dalfopristin, rifampicin, tobramycin, trimethoprim-sulfamethoxazole, vancomycin. Some (15.2%) of the strains were resistant to ampicillin and to penicillin G; 6.8% were resistant to chloramphenicol, 20.3% to enrofloxacin, 16.9% to erythromycin and to ciprofloxacin, 8.5% to clindamycin, and 11.9% to lincomycin. The highest percentages of strains were resistant to tetracycline and oleandomicin (37.3 and 25.4% respectively). Methicillin-resistant staphylococci were also found (3.4%). Only one strain had a multiple antibiotic resistance index > 0.30. The results were statistically analyzed and clustered in 6 groups. This work provides the antibiotic resistance pattern of S. aureus strains isolated from a pigeon slaughtering plant and represents a study on a quite unknown field in meat production

Authentication of European sea bass according to production method and geographical origin by light stable isotope ratio and rare earth elements analyses combined with chemometrics

In this work, stable isotope ratio (SIR) and rare earth elements (REEs) analyses, combined with multivariate data elaboration, were used to explore the possibility to authenticate European sea bass (Dicentrarchus labrax L.) according to: i) production method (wild or farmed specimens); ii) geographical origin (Western, Central or Eastern Mediterranean Sea). The dataset under investigation included a total of 144 wild and farmed specimens coming from 17 different European areas located in the Mediterranean Sea basin. Samples were subjected to SIR analysis (carbon and nitrogen) and REEs analysis (lanthanum, europium, holmium, erbium, lutetium, and terbium). Then, Analytical data were handled by Principal Component Analysis (PCA) and then by Orthogonal Partial Last Square Discriminant Analysis (OPLS-DA), to obtain functional classification models to qualitatively discriminate sea bass according to the conditions under study. OPLSDA models provided good correct classification rate both for production method and geographical origin. It was confirmed that chemometric elaboration of data obtained from SIR and REEs analyses can be a suitable tool for an accurate authentication of European sea bass

SUSCEPTIBILITY OF Listeria monocytogenes STRAINS ISOLATED FROM FOOD TO ANTIMICROBIAL AGENTS

The objective of this study was to evaluate the susceptibility of 40 L. monocytogenes strains isolated from seafood and processing environments to 19 antibiotics currently used in veterinary and human therapy. Susceptibility tests were performed by the automated system VITEK2. Apart from Penicillin, Ampicillin and Trimethoprim-Sulfamethoxazole, for which clinical breakpoint for Listeria susceptibility testing are defined according to the Clinical and Laboratory Standard Institute (CLSI), in the present study the CLSI criteria for staphylococci were applied. This study shows that isolated L. monocytogenes strains are susceptible to the antibiotics commonly used in veterinary and human listeriosis treatment. Very few strains (7,5%) showed a resistance behaviour towards Oxacillin, whereas a variable pattern was showed for Ciprofloxacin and Moxifloxacin. Moreover, an increase in tetracycline resistance, reported by several authors, can not be confirmed in this study, probably due to the different sources of strains isolation. At last, the VITEK2 system represents a rapid and easy-to-use means for antimicrobial susceptibility test of Listeria monocytogenes. In conclusion, because of the increase of antimicrobial resistance showed by L. monocytogenes, a continuous surveillance of emerging antimicrobial resistance among this pathogen is important to ensure effective treatment of human listeriosis. These data can be used for improve background data on antibiotic resistance of strains isolated from food and food environment, even considering the lack of clinical breakpoint provided by the CLSI

Advances in troubleshooting fish and seafood authentication by inorganic elemental composition

The demand for fish and seafood is growing worldwide. Meanwhile, problems related to the integrity and safety of the fishery sector are increasing, leading legislators, producers, and consumers to search for ways to effectively protect themselves from fraud and health hazards related to fish consumption. What is urgently required now is the availability of reliable, truthful, and reproducible methods assuring the correspondence between the real nature of the product and label declarations accompanying the same product during its market life. The evaluation of the inorganic composition of fish and seafood appears to be one of the most promising strategies to be exploited in the near future to assist routine and official monitoring operations along the supply chain. The present review article focuses on exploring the latest scientific achievements of using the multi-elemental composition of fish and seafood as an imprint of their authenticity and traceability, especially with regards to the geographical origin. The scientific literature of the last 10 years focusing on the analytical determination and statistical elaboration of elemental data (alone or in combination with methodologies targeting other compounds) to verify the identity of fishery products is summarized and discussed

Preliminary notes on invasion and proliferation of foodborne Listeria monocytogenes strains

In this study, virulence properties of L. monocytogenes strains isolated from food and food environments were evaluated. In particular, adhesion and invasion efficiencies were tested in a cell culture model (HeLa). Half of the isolates (9/18) exhibited a high invasion index. In particular, the strain isolated from smoked salmon had the highest invasion index. The remaining isolates showed an intermediate invasion index. All environmental isolates belonged to this group. Finally, no isolates revealed a low invasion index. Regarding intracellular growth, all tested isolates had a replication time between 2 and 6 hours. For this reason, they can be considered virulent. In spite of its capability to invade HeLa cells with a medium/high invasion index, a non-haemolytic rabbit isolate did not show any intracellular growth. In conclusion, differences in invasion efficiency and intracellular growth did not seem strictly related to the origin of the strains. Moreover, invasiveness of an organism is not the only requirement for establishing an infection. Virulence of L. monocytogenes also depends on ability to grow intracellularly and to spread from cell to cell. For these reasons, PCR detection of known virulence genes has the potential to gain additional insight into their pathogenic potential. A comprehensive comparative virulence characterization of different L. monocytogenes strains in studies that include tissue culture models and PCR detection of virulence genes will be necessary to investigate differences in human-pathogenic potentials among the subtypes of this bacterium

SHELF –LIFE OF SEA BREAM (SPARUS AURATA) PACKAGED IN MODIFIED ATMOSPHERE: RELATIONSHIPs BETWEEN SENSORY AND MICROBIOLOGICAL PARAMETERS

The research evaluates sensorial and microbiological parameters of gilthead sea bream (Sparus aurata) during storage in MAP. Fish samples, obtained from three off-shore breedings located in Messina, Pisa and Sassari, were analyzed after 1, 5, 8, 12, 15 and 19 days of storage. Sensory assessment was carried out using the Quality Index Method (QIM). Microbiological assays (CMT, CPT, H2S-producing bacteria) were performed on muscle pools. The results show that the shelf-life of gilthead sea bream packaged in MAP as determined by acceptability sensory scores, was lower than 12 days. A relationship between QIM and the microbiological parameter of H2S producing bacteria has been found, even if not it cannot be considered statistically significant according to statistical analysis

Toxoplasma gondii lineages circulating in slaughtered industrial pigs and potential risk for consumers

Toxoplasma gondii is a cosmopolitan zoonotic protozoan parasite, and the consumption of raw or undercooked pig meat is one of the most important sources of T. gondii infection. Three predominant lineages, types I, II, and III, are widespread in Europe. Although still poorly understood, a relationship between each type and the severity of illness represents a public health issue. To gain further knowledge of the genotypes in circulation and of the potential risk for consumers, one heart sample and one diaphragm sample (206 total) were taken from each of 103 pig carcasses at an abattoir in Italy. Then, we used 529-bp repetitive element PCR and a B1 real-time PCR high-resolution melting assay coupled with sequencing to detect and genotype T. gondii isolates. T. gondii DNA was detected in 14 pigs (13.6%, 95% confidence interval ¼ 7 to 20.2%), and types I (3.9%), II (5.8%), and III (3.9%) were identified. We found that heart tissue had a significantly higher PCR positivity rate for T. gondii than did diaphragm tissue. This is Europe’s largest study on genotyping of T. gondii from pigs, and it demonstrates that all three main lineages are present in carcasses of industrially reared pigs in Italy. There is a potential risk to consumers of infection with any or all of the three lineages, and the related clinical consequences should be taken into account. This study suggests that monitoring of T. gondii types in meat is essential, especially in meat that is traditionally eaten raw or that is minimally processed