Viability of Campylobacter jejuni in the refrigerated samples of artificially contaminated pasteurized and UHT milks / Sobrevivência de Campylobacter jejuni em amostras de leite pasteurizado e UHT artificialmente contaminados e mantidas sob refrigeração

Campylobacter is the most prevalent etiologic agent of foodborne gastroenteritis worldwide. Although raw milk is an important source of infection, little is known about the consequences of milk recontamination. This study aimed at verifying the viability of Campylobacter jejuni in pasteurized and UHT milks stored under refrigeration. Both samples were divided into five portions of 100 mL, inoculated with 101 CFU.mL-1 of C. jejuni and stored at 4 C - 7 ºC for 48 h. The procedure was repeated using inoculations of 102, 103 and 104 CFU.mL-1. Aliquots were analyzed immediately after inoculation and after 24 and 48 h to evaluate C. jejuni viability. The microorganism their viability in all of samples. In pasteurized milk a reduction of 1 log cycle occurred after 24 h and low counts after 48 h. Probably, the reduction happened due to the occurrence of microbiota in this milk, which caused competition or inhibition of microorganism growth. UHT milk offered good conditions for bacteria survival in all of the periods. The consumption of contaminated milk, even stored under refrigeration might be a source of infection. Microorganism were more viable in UHT milk than in pasteurized one, probably owing to the absence of competing microorganisms.(AU)

Campylobacter é o agente etiológico mais prevalente em gastroenterites de causa alimentar no mundo. Apesar de o leite cru ser fonte de infecção, pouco se conhece sobre as consequências da recontaminação do leite. A viabilidade de Campylobacter jejuni foi avaliada em leites pasteurizados e UHT mantidos sob refrigeração. Ambos os leites foram divididos em cinco porções de 100 mL, inoculados com 101 UFC.mL-1 de C. jejuni e mantidos de 4 ºC a 7 ºC por 48 horas. Repetiu-se o procedimento, utilizando-se inoculações de 102, 103 e 104 UFC.mL-1. As alíquotas foram analisadas imediatamente após inoculação e depois de 24 e 48 h quanto à viabilidade de C. jejuni. O micro-organismo manteve-se viável em todas as amostras, porém no leite pasteurizado houve redução de 1 ciclo log nas contagens após 24 h e baixas contagens após 48 h. Provavelmente, a redução ocorreu pela presença de microbiota neste leite, que competiu ou inibiu o crescimento de C. jejuni. O leite UHT ofereceu boas condições de sobrevivência em todos os períodos. O consumo de leite contaminado, mesmo em armazenamento refrigerado, pode ser fonte de infecção. O micro-organismo manteve-se mais viável no leite UHT quando comparado ao pasteurizado, provavelmente pela ausência de outros micro-organismos competidores.(AU)

Campylobacter jejuni in commercial eggs

This study evaluated the ability of Campylobacter jejuni to penetrate through the pores of the shells of commercial eggs and colonize the interior of these eggs, which may become a risk factor for human infection. Furthermore, this study assessed the survival and viability of the bacteria in commercial eggs. The eggs were placed in contact with wood shavings infected with C. jejuni to check the passage of the bacteria. In parallel, the bacteria were inoculated directly into the air chamber to assess the viability in the egg yolk. To determine whether the albumen and egg fertility interferes with the entry and survival of bacteria, we used varying concentrations of albumen and SPF and commercial eggs. C. jejuni was recovered in SPF eggs (fertile) after three hours in contact with contaminated wood shavings but not in infertile commercial eggs. The colonies isolated in the SPF eggs were identified by multiplex PCR and the similarity between strains verified by RAPD-PCR. The bacteria grew in different concentrations of albumen in commercial and SPF eggs. We did not find C. jejuni in commercial eggs inoculated directly into the air chamber, but the bacteria were viable during all periods tested in the wood shavings. This study shows that consumption of commercial eggs infected with C. jejuni does not represent a potential risk to human health.(AU)