Listeria monocytogenes is a foodborne pathogen able to adhere and to form biofilms in several materials commonly present in food processing plants. The aim of this study was to evaluate the resistance of Listeria monocytogenes attached to abiotic surface, after treatment with sanitizers, by culture method, microscopy and Quantitative Real Time Polymerase Chain Reaction (qPCR). Biofilms of L. monocytogenes were obtained in stainless steel coupons immersed in Brain Heart Infusion Broth, under agitation at 37 °C for 24 h. The methods selected for this study were based on plate count, microscopic count with the aid of viability dyes (CTC-DAPI), and qPCR. Results of culture method showed that peroxyacetic acid was efficient to kill sessile L. monocytogenes populations, while sodium hypochlorite was only partially effective to kill attached L. monocytogenes (p < 0.05). When, viability dyes (CTC/DAPI) combined with fluorescence microscopy and qPCR were used and lower counts were found after treatments (p < 0.05). Selective quantification of viable cells of L. monocytogenes by qPCR using EMA revelead that the pre-treatment with EMA was not appropriate since it also inhibited amplification of DNA from live cells by ca. 2 log. Thus, the use of CTC counts was the best method to count viable cells in biofilms.

A identificação das espécies de 52 Enterococcus spp. isolados de amostras de alimentos foi realizada empregando-se duas metodologias: sistema API 20 STREP e PCR multiplex. Os resultados obtidos revelaram que 78,9% dos isolados apresentaram resultados diferentes nos dois testes utilizados. Apenas seis E. faecalis e cinco E. faecium apresentaram resultados concordantes pelos dois métodos. PCR multiplex permitiu a identificação completa de um número significantemente maior de enterococos do que o sistema API 20 STREP.

We evaluated the suitability of API 20 STREP and multiplex PCR to speciate 52 Enterococcus spp. obtained from Brazilian foods. A high percentage of isolates (78.9%) presented discrepant results between evaluated tests. Similar results were obtained for six E. faecalis and five E. faecium. The PCR multiplex was more effective than API 20 STREP for complete identification of the isolates.

H. pylori é o agente da maioria dos casos de gastrites e úlceras pépticas. Entretanto, sua forma de transmissão não foi completamente elucidada. Para avaliar a sobrevivência de H. pylori (uma cepa de referência e uma clínica), artificialmente inoculado em amostras de cenoura e alface, porções de 25g das amostras receberam aproximadamente 10(6) UFC/g de H. pylori, e foram embaladas em atmosfera normal e/ou modificada (3% oxigênio, 10% dióxido de carbono, e 87% nitrogênio). Em seguida, foram armazenadas a 8ºC, com enumeração diária da população de H. pylori em ágar Columbia sangue (CBA) e/ou Helicobacter pylori Special Peptone Agar (HPSPA). Quando usamos CBA com antibióticos, o isolado clínico de H. pylori (HP1) foi detectado por até 72 horas nas amostras de alface e cenoura sanitizadas. Em amostras de cenoura esterilizadas, H. pylori HP1 permaneceu viável por até 96 horas. CBA sem antibióticos permitiu a recuperação de H. pylori ATCC 43629, a partir de amostras de cenoura embaladas em ambas as atmosferas, por até 120 horas. Nossos resultados reforçam que a transmissão de H. pylori, através do consumo de água e alimento contaminados, ainda não pode ser descartado.

Helicobacter pylori is known, worldwide, as the causative agent of gastric diseases. However, its transmission route has not been completely understood. To evaluate the survival of H. pylori (a clinical and a reference strain) artificially inoculated on lettuce and carrot samples, portions of 25 g were inoculated with approximately 10(6) CFU/g of H. pylori and packed under normal and/or modified atmosphere (3% oxygen, 10% carbon dioxide, and 87% nitrogen). The inoculated food samples were stored at 8ºC, with daily enumeration of H. pylori populations on Columbia blood agar (CBA) and/ or Helicobacter pylori Special Peptone Agar (HPSPA). When CBA with antibiotics was used, the clinical isolate H. pylori HP1 was detected for up to 72 h in sanitized lettuce and carrot. In sterilized carrot samples, H. pylori HP1 remained viable for up to 96 h. The CBA without antibiotics allowed the recovery of H. pylori ATCC 43629, from carrot samples stored in both atmospheres tested, for up to 120 hours. Our results reinforce that foodborne transmission of H. pylori cannot be disregarded yet.

Vinte amostras de carnes e produtos cárneos brasileiros foram analisadas com a finalidade de se isolar bactérias láticas produtoras de bacteriocina, através do método de antagonismo em ágar, utilizando Lactobacillus sake ATCC 15521 como microrganismo indicador. Baseado na coloração de Gram, reação com KOH, teste de catalase e teste de fermentação de 49 carboidratos (API 50 CH), três das sete cepas com características antagonísticas foram classificadas como Lactobacillus curvatus, uma como Leuconostoc mesenteroides e uma como Leuconostoc sp. Duas cepas não puderam ser identificadas usando apenas estes testes. Os inibidores produzidos por essas cepas mostraram-se sensíveis a proteases. A inibição devido a bacteriófagos líticos foi descartada e assim as culturas foram classificadas como bactérias láticas produtoras de bacteriocina. Quatro cepas apresentaram atividade antilisterial, e conseqüentemente um potencial de utilização como bioconservadores em produtos cárneos.

Twenty samples of Brazilian meat and meat products were screened by the agar overlay method for bacteriocin-producing lactic acid bacteria, using Lactobacillus sake ATCC 15521 as indicator strain. Based on Gram staining, KOH reaction, catalase test and fermentation of 49 carbohydrates (API 50 CH), three out of seven isolates with confirmed antagonist properties were identified as Lactobacillus curvatus, one as Leuconostoc mesenteroides and one as Leuconostoc sp. Two isolates could not be properly identified using these tests. The inhibitors produced by these strains were sensitive to proteases. Inhibition due to lytic bacteriophages was ruled out, so the isolates were classified as bacteriocin-producing lactic acid bacteria. Four of them presented antilisterial activity and a potential application as biopreservatives in meat systems.