Pesquisa de bactérias patogênicas em leite pasteurizado tipo C comercializado na cidade do Recife, Pernambuco, Brasil

Revista da Sociedade Brasileira de Medicina Tropical 01/2001; DOI: 10.1590/S0037-86822001000200003
Source: DOAJ


Visando complementar as informações sobre a qualidade microbiológica do leite comercializado na cidade do Recife, foram analisadas 250 amostras de leite pasteurizado tipo C e 50 amostras de leite cru para a pesquisa de Yersinia enterocolitica e Listeria monocytogenes, bactérias patogênicas capazes de se desenvolverem em temperatura de refrigeração. Y. enterocolitica não foi encontrada em nenhuma das amostras analisadas, entretanto foi detectada a presença de Y. intermedia e Y. frederiksenii, espécies ambientais que se comportam como patógenos oportunistas. L. monocytogenes também não foi encontrada, mas, através da metodologia empregada para seu isolamento foi obtido um isolamento de Salmonella Montevideo em uma amostra de leite pasteurizado e outro em leite cru. Além dessas, várias outras bactérias foram encontradas, supondo-se que a ampla microbiota crescida nos meios empregados pode ter interferido no isolamento da Y. enterocolitica e L. monocytogenes.

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    ABSTRACT: A study was done in 112 milk samples and milk derivative samples, being 46 homemade cheese (QC) and industrialized cheese (QI) and 66 raw milk (LC) and pasteurized milk (LPC), in order to quantify mesophilics aerobics (AM), positive coagulase Staphylococci (SCP), MPN of totals coliforms (CT) and fecals (CF) and a research was made on E. coli, Salmonella sp., Pseudomonas aeruginosa and Listeria sp. For Listeria, the FDA official methodology was adopted including cold enrichment stage (45 days /4°C) and microaerofilic system. Count averages of AM for QI (4.88x109 CFU g-1) were significantly different (P <0.05) from QC. SCP counting showed 47.83% (QC) and 34.78% (QI) which exceeded default value. Averages (MPN g-1) for CT were 2.39x105 (QC) and 2.48x105 (QI); and for CF was 1.67x105 (QI). E. coli was detected in QC: 78.26% and in QI: 60.87%, Salmonella sp. was isolated in QI: 8.70% and P. aeruginosa was isolated in 100% of QC and QI. Listeria sp. was isolated before and after of cold enrichment and it was identified L. innocua 6a, 6b, 4ab and untypable. In the milk sampling the positivity for E. coli was 75.76% (LC), 39.39% (LPC) and 12.12% with isolation of Salmonella sp in LPC. It was concluded by the results that both milk and cheese were disqualified for consumption for offering potential risks to public health.
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    ABSTRACT: To determine the contribution of enterococci and coliforms from bovine faeces and teats to contamination of raw milk. Methods: Putative enterococci (n = 301) and coliforms (n = 365) were isolated from bovine faeces (n = 20), cows' teats (n = 20), the raw milk (n = 1) and the milking environment (n = 4) on one farm. The clonal relationships of each bacterial group were investigated using Pulsed-Field Gel Electrophoresis of genomic macrorestriction fragments. Representatives of the different clusters of enterococci were identified by molecular techniques including rep-PCR, SDS protein profiling, Fluorescent Amplified Fragment Length Polymorphism (FAFLP), phenylalanyl-tRNA synthase (pheS) sequence analysis and/or 16S rDNA gene sequencing. Coliforms were identified by API 20E strips. The majority of the bovine faecal enterococcal isolates were identified as a potential new species of Aerococcus (100 isolates); E. faecium (28 isolates), and Aerococcus viridans (28 isolates) were also found. All coliform isolates from the bovine faeces were identified as Escherichia coli. The coliforms present in the milk were Hafnia alvei, Serratia liquefaciens, Yersinia enterocolitica and Enterobacter amnigenus. No E. coli, Enterococcus or Aerococcus from the bovine faeces were found in the milk. A single clone of H. alvei was found in the water, the milking equipment and the milk, suggesting that the water was the source of the organism in the milk. No vancomycin-resistant aerococci or enterococci were found while most of the isolates tested showed the presence of at least one virulence gene. The milk-sock retained strains that adhered to particulate faecal material. Coliforms were present at approx. 2 orders of magnitude greater than enterococci in the bovine faeces. The results imply that bovine faeces are not an important source of contamination of raw milk with enterococci or coliforms. The results confirm those of two previous studies (Gelsomino et al. 2001, Int J Food Microbiol71, 177-188 and Kagkli et al. 2007, Int J Food Microbiol114, 243-251) on two other farms. The three studies show that contamination of milk by enterococci, lactobacilli and coliforms of bovine faecal origin is extremely low. The results also suggest that where raw milk is implicated in food infection, other factors in addition to faecal contamination must be involved.
    Full-text · Article · Dec 2007 · Journal of Applied Microbiology
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