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The aim of the research was to compare the microbiological quality of dairy products derived from organic and conventional farming. The test material consisted of milk and milk products (natural yoghurt, cream, curd cheese, rennet ripening cheese, milk). Investigated products were subjected to microbiological analysis and marked for the number of Enterococcus sp., Staphylococcus aureus, yeast and moulds, Escherichia coli as well as to state the presence of Salmonella sp. in them. All samples were free of Salmonella sp. Escherichia coli occurred in 2 samples of curd cheese from organic production. Products derived from organic and conventional production didn’t differ in the average number of microorganisms depending on the type of dairy product, with the exception of ripening rennet cheese, which showed a significant difference in the amount of Staphylococcus aureus.

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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. HIGHLIGHTS

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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. Material and 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 epidermidis 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 PROLEX TM STAPH XTRA LATEX KIT. Results. The results obtained show that 1/3 of the samples of commercial strawberries analyzed were colonized 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 log 10 CFU/g and S. epidermidis by 0.47 log 10 CFU/g when they were subjected to rinsing after harvesting. Effective inhibition of MRSA in strawberries is obtained when fluidization technology is applied at-40ºC.

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. Material and 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 epidermidis 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 PROLEX TM STAPH XTRA LATEX KIT. Results. The results obtained show that 1/3 of the samples of commercial strawberries analyzed were colonized 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 log 10 CFU/g and S. epidermidis by 0.47 log 10 CFU/g when they were subjected to rinsing after harvesting. Effective inhibition of MRSA in strawberries is obtained when fluidization technology is applied at -40ºC.

Produkty pochodzenia wodnego należą do głównych źródeł białka i innych składników odżywczych. Odgrywają one istotną rolę w diecie człowieka. Staphylococcus aureus uważane są za jedne z najczęściej występujących na świecie patogenów przenoszonych przez żywność. S. aureus nie jest rodzimą florą produktów pochodzenia wodnego, jednak bakterie te można izolować ze świeżo złowionych ryb. Dodatkowe zanieczyszczenie tych produktów może wynikać z niewłaściwego obchodzenia się z nimi, przechowywania w nieodpowiednich warunkach, przenoszenia patogenu przez pracowników, jak też może być następstwem zanieczyszczenia krzyżowego. Powszechne stosowanie antybiotyków w ostatnich latach doprowadziło do gwałtownego wzrostu oporności na antybiotyki wśród bakterii patogennych. W związku z powyższym niniejsze badania przeprowadzono w celu oceny występowania S. aureus metycylinoopornych (MRSA) w produktach pochodzenia wodnego o różnym stopniu przetworzenia (mrożonych, wędzonych, marynowanych i surowych). Na podstawie przeprowadzonych badań wykazano, że MRSA najczęściej występował w próbach mrożonych (ok. 83 %), a najrzadziej – w produktach marynowanych (ok. 29 %). Pomimo tego, że najniższy odsetek prób, w których stwierdzono występowanie S. aureus metycylinoopornych, stanowiły produkty marynowane, to najniższą średnią ilość tych bakterii stwierdzono w przetworach wędzonych (0,54 log jtk/g). Ogólnie ok. 41 % prób było zanieczyszczonych tymi bakteriami.