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Listeria monocytogenes, Escherichia coli e Estafilococos coagulase positiva em queijos alentejanos curados de leite cru
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Resumo(s)
Em Portugal, existe um grande consumo de queijos de leite cru, não só por serem um produto tradicional como também pelas suas características organoléticas que satisfazem os consumidores. No entanto, por não sofrerem qualquer tratamento térmico acarretam mais perigos para a saúde dos consumidores.
Pretendeu-se neste estudo colmatar a falta de informação que existe sobre a presença de microrganismos como Listeria monocytogenes, Escherichia coli e Estafilococos coagulase positiva em queijos alentejanos curados de leite cru.
Foram analisadas 89 amostras, tendo-se detetado a presença de Listeria monocytogenes em 15 (16,9%), com quatro excedendo o valor permitido por lei. A sequenciação total do genoma dos isolados de Listeria monocytogenes revelou a presença de dois clusters, A e B. Adicionalmente, três dos isolados fizeram cluster com isolados associados a casos clínicos de 2016-2020, 2018-2019 e 2022. O serotipo mais prevalente foi o 1/2a, 3a com 80% de ocorrência.
No que diz respeito à E. coli foram encontradas 29/89 (32,6%) amostras não conformes (≥104 ufc/g e/ou presença de isolados de E. coli extraintestinal (ExPEC)). Dos isolados hemolíticos de E. coli, três foram identificados como ExPEC, sendo que dos 55 isolados testados, 15 apresentaram resistência a pelo menos um antibiótico (27,3%) e seis isolados apresentaram múltiplas resistências (MDR), tendo sido identificados como ExPEC.
No caso de Estafilococos coagulase positiva, de um total de 89 amostras, 15 encontravam-se insatisfatórias (≥104 ufc/g). Na pesquisa de enterotoxinas estafilocócicas obtiveram-se dois resultados positivos.
Tendo em conta todos os critérios microbiológicos definidos para os microrganismos testados, podemos concluir que das 29 marcas testadas, quatro (13,8%) apresentam qualidade microbiológica satisfatória, uma marca é questionável (3,4%) e as restantes 24 marcas são insatisfatórias e/ou potencialmente perigosas para a saúde (82,8%).
Dada a perigosidade destes microrganismos, sugerimos uma maior fiscalização e verificação dos queijos de leite cru.
In Portugal, there is a large consumption of raw milk cheeses, not only because it is a traditional product, but also because of its organoleptic characteristics that satisfy consumers. Because these products do not suffer any heat treatment, may pose more dangers to the health of consumers. The aim of this study was to overcome the lack of information that currently exists on the presence of microorganisms such as Listeria monocytogenes, Escherichia coli and coagulase-positive Staphylococci in cured Alentejo raw milk cheeses. A total of 89 samples were analyzed, where it was possible to verify the presence of Listeria monocytogenes in 15 (16.9%), four of which exceeding the value allowed by law. The sequencing of Listeria monocytogenes isolates revealed the presence of two clusters A and B. Additionally, three of the isolates were clustered with clinical cases from 2016-2020, 2018-2019 and 2022. The most prevalent serotype was 1/2a, 3a with 80% of occurrence. Regarding E. coli, 29/89 (32.6%) non-compliant samples (≥104 cfu/g and/or presence of extraintestinal E. coli (ExPEC)) were found. Of the hemolytic E. coli isolates, three were identified as ExPEC, and of the 55 tested isolates, 15 showed at least one antibiotic resistance (27.3%) and six isolates showed multiple drug resistances (MDR) and were also identified as ExPEC. In the case of coagulase-positive Staphylococci, from a total of 89 samples, 15 were unsatisfactory (≥104 ufc/g). Regarding the search for staphylococcal enterotoxins, two positive results were obtained. Taking into account all the microbiological criteria defined for the microorganisms tested, we can conclude that of the 29 brands tested, four brands (13.8%) present satisfactory microbiological quality, one brand is questionable (3.4%) and the remaining 24 brands are unsatisfactory/ potentially hazard to health (82.8%). Given the danger of these pathogenic microorganisms, we suggest greater inspection and verification of raw milk cheeses.
In Portugal, there is a large consumption of raw milk cheeses, not only because it is a traditional product, but also because of its organoleptic characteristics that satisfy consumers. Because these products do not suffer any heat treatment, may pose more dangers to the health of consumers. The aim of this study was to overcome the lack of information that currently exists on the presence of microorganisms such as Listeria monocytogenes, Escherichia coli and coagulase-positive Staphylococci in cured Alentejo raw milk cheeses. A total of 89 samples were analyzed, where it was possible to verify the presence of Listeria monocytogenes in 15 (16.9%), four of which exceeding the value allowed by law. The sequencing of Listeria monocytogenes isolates revealed the presence of two clusters A and B. Additionally, three of the isolates were clustered with clinical cases from 2016-2020, 2018-2019 and 2022. The most prevalent serotype was 1/2a, 3a with 80% of occurrence. Regarding E. coli, 29/89 (32.6%) non-compliant samples (≥104 cfu/g and/or presence of extraintestinal E. coli (ExPEC)) were found. Of the hemolytic E. coli isolates, three were identified as ExPEC, and of the 55 tested isolates, 15 showed at least one antibiotic resistance (27.3%) and six isolates showed multiple drug resistances (MDR) and were also identified as ExPEC. In the case of coagulase-positive Staphylococci, from a total of 89 samples, 15 were unsatisfactory (≥104 ufc/g). Regarding the search for staphylococcal enterotoxins, two positive results were obtained. Taking into account all the microbiological criteria defined for the microorganisms tested, we can conclude that of the 29 brands tested, four brands (13.8%) present satisfactory microbiological quality, one brand is questionable (3.4%) and the remaining 24 brands are unsatisfactory/ potentially hazard to health (82.8%). Given the danger of these pathogenic microorganisms, we suggest greater inspection and verification of raw milk cheeses.
Descrição
Tese de mestrado, Qualidade Alimentar e Saúde, 2022, Universidade de Lisboa, Faculdade de Farmácia.
Palavras-chave
Segurança dos alimentos Listeria monocytogenes Escherichia coli Estafilococos coagulase positiva Queijos alentejanos curados de leite cru Teses de mestrado - 2022