Alexandra Esteves

Huffmanela sp. (Nematoda: Trichosomoididae) muscular parasite from Trisopterus luscus captured off the Portuguese coast.

Four samples of Trisopterus luscus exhibiting unusual black spots on their musculature were obtained from catches made on different days and were rejected as unsuitable for consumption. Bipolar eggs somewhat resembling those of the nematode genus Huffmanela (Nematoda: Trichosomoididae) were identified as the cause of these black spots. Microscopic analysis revealed the presence of dark-shelled trichinelloid embryonated eggs dispersed throughout the muscle tissue, 73 to 94 x 40 to 59 microm in size, with large polar plugs 14 to 22 microm wide. However, the morphology and distribution of the observed eggs were not compatible with any previously described Huffmanela species. Intracellular nematodes were also observed in muscle cells. In 2 samples, sectioned nematode specimens were observed in other locations as well: the lymphatic vessel of intestine submucosa and the dermal lymphatic vessel. This could be due to nematode migration inside the infected fish. The presumed identification of Huffmanela sp. in a new host (Trisopterus luscus), and in a new location (Atlantic Ocean) supports the belief that these parasites could be widely distributed, particularly in marine fishes. In view of these factors, together with the observed egg morphology, it is possible that these specimens represent a new, unidentified Huffmanela species.

Multiple correspondence analysis and random amplified polymorphic DNA molecular typing to assess the sources of Staphylococcus aureus contamination in alheira production lines.

Sources and tracing of Staphylococcus aureus in alheira (garlic sausage) production were evaluated by multifactorial correspondence analysis (MCA) of occurrence data and a random amplified polymorphic DNA (RAPD) on S. aureus isolates. Samples from four production lines, four different production batches, and 14 different sampling sites (including raw material, different contact surfaces, and several stages of alheira manufacturing) were analyzed at four sampling times. From the 896 microbial analyses completed, a collection of 170 S. aureus isolates was obtained. Although analysis of the occurrence data alone was not elucidative enough, MCA and RAPD-PCR were able to assess the sources of contamination and to trace the spread of this microorganism along the production lines. MCA results indicated that the presence of S. aureus in alheira was related to its presence in the intermediate manufacturing stages after heat treatment but before stuffing in the casings. It was also possible to associate a cross-contamination path related to handler procedures. RAPD-PCR typing in accordance to MCA results confirmed the cross-contamination path between the raw material and casings and the role of handlers as an important cross-contamination vehicle.

Efficacy of LISTEX P100 at Different Concentrations for Reduction of Listeria monocytogenes Inoculated in Sashimi

Sushi restaurants have become quite popular in Europe, with an increase in the consumption of the sashimi speciality. Pathogenic bacteria such as Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus have been reported in this kind of food. Controlling the presence and multiplication of L. monocytogenes is a challenge for food safety management systems owing to its ubiquitous presence and psychrotrophic growth. Bacteriophages have been used as pathogenic biocide agents for decades. The bacteriophage P100, present in LISTEX P100, was used in this study to understand the possibility of implementing a new critical control point for L. monocytogenes in sashimi preparation and sale. Different concentrations of LISTEX P100 were used for reduction of L. monocytogenes in inoculated samples at 3 and 22°C. The reduction in initial counts of 2 log CFU/g was effective in the first 24 h with the 8-log PFU/g inoculation. Promising results were obtained in assays with the 6-log CFU/g initial counts and the 8-log PFU/g inoculation, at 22°C, achieving a maximum reduction of 4.44 log CFU/g, compared with the control group. These results seem to confirm that bacteriophages can be an option in reducing the population of the L. monocytogenes pathogenic bacteria in sashimi, mainly in takeaway sales.

Antimicrobial Susceptibility of Coagulase-Positive and Coagulase-Negative Staphylococci in Ready-to-Eat Sashimi

ABSTRACT The aim of this study was to investigate the antimicrobial susceptibility pattern of Staphylococcus spp. isolated from sashimi meals collected in Japanese restaurants from northern Portugal. One hundred and thirty-six isolates of Staphylococcus spp. were recovered from sashimi samples. The antimicrobial susceptibility test showed high levels of resistance to β-lactams, macrolides, and lincosamides. All Staphylococcus isolates were sensitive to trimethoprim-sulfamethoxazole, ciprofloxacin, and chloramphenicol. Multidrug-resistant staphylococci (25%) were found in sashimi samples. It is of the utmost need to improve the hygienic practices in handling in order to reduce the occurrence of Staphylococcus species, potentially resistant to antimicrobial agents.