Enterococcus spp. in fish: Analysis of the presence and resistance in samples from Tri-City, Poland.

The growing concern over antibiotic resistance in foodborne pathogens necessitates comprehensive assessments of its prevalence and associated risks in various food products. The present study aimed to assess the occurrence of Enterococcus spp. in samples of fish purchased at various points of sale in the Tricity region. The selection of products (n = 74) was based on their availability and included both fish caught in the Baltic region and products imported from, Vietnam, China, Norway, and European Union (EU) countries. For bacterial isolation, samples were inoculated into selective broth, and the growth of enterococci was assessed based on turbidity. Positive cultures were confirmed by a change in color in bromocresol purple broth and were isolated on Slanetz-Bartley agar. Bacteria were present in all tested samples regardless of the degree of raw material processing as follows: frozen (F)- 55%, fresh/raw (FS)- 70.6%, thawed (DF)- 30%, smoked (S)- 50%, and the packaging methods, modified atmosphere packaging (MAP)- 34.4%, unit packaging (UP)- 75%, and sold in bulk (SB)- 76.9%, with an overall frequency of occurrence of 58.1%. The number of bacteria ranged from not detected to 4.28-log cfu/g, with the lowest mean values for thawed fish and those packed in MAP. Tests conducted on 24 strains isolated from samples showed their varied sensitivity to tetracyclines. Single cases of multidrug resistance of the tested strains were also observed. The conducted statistical analysis did not show statistically significant differences in the count of enterococci based on the origin, degree of processing, or packaging (p < 0.05). Moreover, differences in strain sensitivity to ampicillin were observed. Detected cases of resistance, especially to tetracycline, require careful monitoring and action to limit the health risks associated with resistant bacterial strains in food products.

Influence of Tagetes patula and Viola tricolor on survival of Staphylococcus aureus ATCC 25923.

So far, no studies have assessed the antibacterial properties of macerates of flower petals intended for human consumption. Previous studies have focused on the role of extracted flower components in inhibiting bacterial growth, not considering the petal tissue as a mixture of different components. The aim of this study was to assess the inhibitory effect of unpreserved macerates and juices derived from edible flower petals of Viola tricolor and T. patula on the population of Staphylococcus aureus ATCC 25923. Evaluation of the biostatic properties of flowers was carried out in two stages: using the Baird-Parker RPF culture method and the disc diffusion method. The reduction in the number of staphylococci by the macerates of the petals and their mixtures did not exceed 11% of the inoculum value. A low degree of inhibition of S. aureus ATCC 25923was found with T. patula macerate and sap in studies using both methods. The diffusion disc method in the study revealed the synergistic effect of the petals of both species on S. aureus ATCC25923 cells.

Presence of Antibiotic-Resistant Staphylococcus aureus in Fish and Seafood Originating from Points of Sale in the Tri-City Area (Poland).

ABSTRACT: Infections by methicillin-resistant Staphylococcus aureus (MRSA) is gradually increasing in the community. There is a potential public health hazard resulting from S. aureus contamination of seafood, which is mainly due to unhygienic handling, processing, and storage environments. In Poland, the limits provided in European Commission Regulation 1441/2007 refer to the presence of Escherichia coli and S. aureus in shelled and shucked products of cooked crustaceans and molluscan shellfish. This study was designed to evaluate the occurrence of MRSA in samples of fish and seafood from commercial outlets located in the Tri-City area (Poland). In this study, we investigated a 44 food samples, including fish and seafood collected from various retail outlets in the Tri-City area of Poland. The first stage of staphylococcus isolation was initial culture in Giolitti-Cantoni broth. After 24 h, if blackening had occurred at the bottom (or there was general blackening of the medium), the samples were spread plated onto a CHROMagar MRSA base. The cultures were then incubated for 24 h at a temperature of 37°C. Of the 44 samples, 26 were positive for MRSA. The samples most often contaminated with MRSA were cephalopods (6 of 9) and crustaceans (10 of 15), followed by samples taken from mollusks (4 of 7) and fish (6 of 13). The correlation between the species from which the samples were obtained and the presence of S. aureus was not significant (P > 0.05). The high frequency of occurrence of MRSA in these products points to the potential risk of transmission of diseases through the food chain. The results obtained are significant and useful for S. aureus risk assessment programs for aquatic products.

Identification and Assessment of the Behavior of Methicillin-Resistant Staphylococci in Cheese.

This study was carried out with the aim of identifying and assessing methicillin-resistant Staphylococcus aureus (MRSA) during lactic acid cheese storage. The study involved 30 assortments of lactic acid cheese and 21 cheeses with S. aureus TWP11616 (MRSA). Results showed low MRSA contamination levels in lactic acid cheese. The majority of cow and goat lactic acid cheese samples (more than 72%) were characterized by a low level of MRSA (≤10 CFU/g). With regard to cow and sheep lactic acid cheese, methicillin-resistant Staphylococcus spp. contamination levels of ≥100 CFU/g were found in 88 and 100% of samples, respectively. The microbial dynamics of MRSA changes in lactic acid cheese suggest a significant reduction in contamination levels after 4 days of product storage, and this decrease is likely not dependent on the type of packaging method.

Identification and study of the behavior of S. aureus and S. epidermidis in fresh and frozen strawberries.

BACKGROUND: Methicillin-Resistant Staphylococcus aureus (MRSA), which is resistant to many antibiotics, creates a serious problem for human health if present in food. This study aimed to assess the quality of commercially-available fresh and frozen strawberries and to compare the behavior of staphylococci in these fruits as affected by the temperature of freezing. METHODS: The research material included different species of fresh strawberries and strawberries frozen with the fluidization method to –40°C and packaged in an industrial environment. These were checked for the presence of Staphylococcus aureus resistant to methicillin (MRSA). The strawberries were purchased at food markets in the Tricity and were divided into two groups (A and B). Group A was analyzed without washing, group B was washed in sterile, distilled water for 15 minutes. The strawberries were placed in sterile PE/PA bags. Then 1 mL of Staphylococcus aureus Rosenbach ATCC 25923 and Staphylococcus epi- dermidis ATCC 12228 of known inoculum were added to each bag (except the control samples). The samples were mixed thoroughly and then hermetically sealed. The samples were then frozen and stored in the freezer at a temperature of –18 ±2°C for 2 months. In the material being tested Staphylococcus aureus was cultured in selective Baird-Parker RPF Agar. Incubation was carried out at a temperature of 37°C for 48 hours in sterile conditions. After 48 hours of incubation, characteristic colonies were transferred onto the reaction field of the PROLEXTM STAPH XTRA LATEX KIT. RESULTS: The results obtained show that 1/3 of the samples of commercial strawberries analyzed were colo- nized by methicillin-resistant Staphylococcus aureus (MRSA). The process of fruit washing was observed to reduce the number of samples containing MRSA from 11.7 to 8.3%. There was no significant difference in the size of the S. aureus ATCC 25923 population after freezing the strawberries at –18°C, depending on the particular washing process for these fruits. The analysis of strawberries frozen with the fluidization method at –40°C showed a minimum contamination degree with S. aureus after the period of storage. CONCLUSIONS: Studies have shown that MRSA are present in 15.4% of strawberries obtained from the field. Storing strawberries frozen at –18ºC causes a reduction in the number of S. aureus by 0.16 log10CFU/g  and S. epidermidis by 0.47 log10CFU/g when they were subjected to rinsing after harvesting. Effective inhibition of MRSA in strawberries is obtained when fluidization technology is applied at –40ºC.

[The influence of microbiological factors on the mass of plastics laminates used for packaging of lactic acid cheese]. / Wplyw czynników mikrobiologicznych na mase laminatów stosowanych do pakowania twarogów.

The study aimed at assessing changes of physical properties of package lactic acid cheese and the PA/PE and Cryovac laminates after storage of this products. The fluctuation of water in the product and swelling of packaging caused changes in their mass. The changes in the packaging mass could also result from the interactions between micro-organisms present in product. It was found that staphylococci, enterococci and Escherichia coli were the micro-organisms that had contributed to changes of packaging mass to a highest degree. Changes were described with the help of response surface models.

[Influence of microbiological quality of lactic acid cheese on water phase in conditions of hermetic packing]. / Wplyw jakosci mikrobiologicznej twarogów na faze, wodna w warunkach pakowania hermetycznego.

Aim of research was to assess the influence of lactic acid cheese micro-flora on water phase fluctuation between surface of products and the packaging. Results of research showed that changes of water content could be expressed with the help of polynomial cubic equation. From linear correlation equations describing level of micro-flora in lactic acid cheese and water content it resulted micro-organisms had a significant influence on the water phase fluctuation. Values of determined coefficients of determination suggested that yeast, enterococci and staphylococci had a significant influence on water fluctuation between product and the packaging.

[Assessment of the probability of encountering staphylococcal enterotoxins in lactic acid cheese packaged in laminates]. / Ocena prawdopodobienstwa wystepowania gronkowców i enterotoksyny gronkowcowej w twarogach pakowanych w laminaty z tworzyw sztucznych.

Immunoassay methods were used to identify the presence of staphylococcal enterotoxins in lactic acid cheese vacuum and non-vacuum packed. There was assessed the probability of encountering staphylococcal enterotoxin in cheese dependent on different systems of packaging, count of staphylococcal cells, intensiveness of coagulase synthesis and tightness of packaging. The presence of enterotoxin was identified in 5% of researched samples of products stored for 14 days. The influence of packaging system and tightness on presence of enterotoxin was observed. The probability of presence of staphylococcal and enterotoxin in relation to researched factors was presented by the mathematical models.