Mycobacteria in Minas cheese commercialized in open fairs in São Paulo, Brazil / Mycobacteria em queijos tipo Minas comercializados em feiras-livres de São Paulo, Brasil

Mycobacterium bovis is the causative agent of bovine tuberculosis, a disease that affects dairy herds throughout the Brazilian territory, constituting a neglected zoonosis transmitted by raw milk and its derivatives. In this study, we evaluated the presence of M. bovis and other mycobacteria in Minas cheese obtained from open fairs in the city of São Paulo between 2012 and 2013. Samples (n = 133) were decontaminated using hexa-cetylpyridinium chloride and seeded on Stonebrink­Leslie medium. The isolates were submitted to molecular identification by TB Multiplex PCR targeting the 16S rRNA gene and amplicon nucleotide sequencing. From 16 cheese samples (12%), we obtained 26 putative colonies of Mycobacterium spp, none of which belonged to any of the Mycobacterium tuberculosis, Mycobacterium avium, or Mycobacterium intracellulare complexes. Phylogenetic analysis showed that sample sequences were grouped in a clade that includes only non-tuberculous mycobacteria with proximity to sequences obtained from Mycobacterium novocastrense (3 sequences), Mycobacterium holsaticum (1 sequence), and Mycobacterium elephantis (2 sequences). Although no epidemiological evidence was found regarding the importance of oral transmission of mycobacteria in healthy people, their importance in the immunosuppressed population remains uncertain.(AU)

Mycobacterium bovis é o agente da tuberculose bovina, doença que acomete o rebanho em todo território brasileiro e é uma negligenciada zoonose transmitida pelo leite e seus derivados. Este trabalho avaliou a presença de M. bovise outras micobactérias, em queijo minas meia-cura, obtidos em feiras-livres na cidade de São Paulo, entre os anos de 2012 e 2013. As amostras (n = 133) foram descontaminadas pelo método HPC (hexa-cetyl-pyridinium chloride) e semeadas em meio Stonebrink Leslie. Os isolados foram submetidos à identificação molecular por PCR TB multiplex, pesquisando-se o gene 16S rRNA, e ao sequenciamento nucleotídico. Dezesseis amostras (12%) possuiam 26 colônias sugestivas de Mycobacterium spp, mas nenhuma delas pertencia aos complexos Mycobacterium tuberculosis, Mycobacterium avium e Mycobacterium intracellulare. A análise filogenética mostrou que todas as amostras estavam agrupadas em clados que incluem apenas micobactérias não tuberculosas (MNT), sendo que algumas possuiam proximidade com sequências obtidas de Mycobacterium novocastrense (3 sequências), Mycobacterium hosaticum(1 sequência) e Mycobacterium elephantis (2 sequências). Embora no momento não haja evidência epidemiológica da importância da transmissão oral das micobactérias pra indivíduos saudáveis, sua importância na população imunossuprimida ainda é incerta.(AU)

Control of Listeria monocytogenes growth in soft cheeses by bacteriophage P100

The purpose of this study was to determine the effect of bacteriophage P100 on strains of Listeria monocytogenes in artificially inoculated soft cheeses. A mix of L. monocytogenes 1/2a and Scott A was inoculated in Minas Frescal and Coalho cheeses (approximately 10(5) cfu/g) with the bacteriophage added thereafter (8.3 x 10(7) PFU/g). Samples were analyzed immediately, and then stored at 10 ºC for seven days. At time zero, 30 min post-infection, the bacteriophage P100 reduced L. monocytogenes counts by 2.3 log units in Minas Frescal cheese and by 2.1 log units in Coalho cheese, compared to controls without bacteriophage. However, in samples stored under refrigeration for seven days, the bacteriophage P100 was only weakly antilisterial, with the lowest decimal reduction (DR) for the cheeses: 1.0 log unit for Minas Frescal and 0.8 log units for Coalho cheese. The treatment produced a statistically significant decrease in the counts of viable cells (p < 0.05) and in all assays performed, we observed an increase of approximately one log cycle in the number of viable cells of L. monocytogenes in the samples under refrigeration for seven days. Moreover, a smaller effect of phages was observed. These results, along with other published data, indicate that the effectiveness of the phage treatment depends on the initial concentration of L. monocytogenes, and that a high concentration of phages per unit area is required to ensure sustained inactivation of target pathogens on food surfaces.

Frecuencia de Listeria spp., en quesos colombianos costeños / Frequency of Listeria spp. in coastal Colombian cheeses

Objetivo. Determinar la frecuencia de Listeria spp., en quesos frescos costeños, distribuidos en plazas de mercado populares de las ciudades de Montería y Cereté. Materiales y métodos. Teniendo en cuenta la importancia económica de esta zona ganadera para Colombia se tomaron 217 muestras entre Junio y Agosto de 2005, los aislamientos obtenidos fueron identificados por pruebas bioquímicas presuntivas, PCRMúltiple (L1-U1/LF-LR) y pruebas bioquímicas para confirmación de especie. Adicionalmente, se determinó la frecuencia de las especies del género y se caracterizó la resistencia antimicrobiana de las cepas de mayor frecuencia. Resultados. Las pruebas bioquímicas y la PCR detectaron 49 aislamientos positivos para Listeria (22.58%), de los cuales 16.33% (8/49) correspondieron a Montería y 24.40% (41/168) a Cereté. La frecuencia por especies fue 14.75% para L. ivanovii, 2.30% para L. innocua, 1.84% para L. welshimeri y 1.38% para L. seeligeri, no se detectó L. monocytogenes. Sólo 3/32 cepas de L. ivanovvi (9.38%) mostraron resistencia a penicilina, estreptomicina y eritromicina respectivamente. Conclusiones. Los resultados confirman que los quesos costeños están frecuentemente contaminados con Listeria spp. La presencia de L. ivanovvi patógeno involucrado en algunos casos de infecciones oportunistas en humanos y L. innocua; microorganismo utilizado en muchas industrias de alimento como indicador del grado o calidad de sanitización; demuestra que las condiciones de producción y expendio no son adecuadas y que el consumo de queso costeño no es seguro. La resistencia antimicrobiana aunque baja muestra posibilidades para la transmisión horizontal y/o vertical de los genes de resistencia.