No abstract

The aim of this study was to investigate the prevalence of thermophilic Campylobacter in the broiler production chain of southern Brazil, by evaluating broiler farms and slaughter line samples, and to determine the genetic diversity, antimicrobial resistance, and virulence genes of the isolates. Of the 140 samples investigated in this study, 75 (53.6%) were positive for thermophilic Campylobacter, and all isolates were identified by phenotypic and molecular tests as C. jejuni. The resistance to nalidixic acid was the most common (74%), followed by resistance to enrofloxacin (67.3%) and ciprofloxacin (37.1%). However, there was no resistance to the macrolides tested which are recommended for the treatment of human campylobacteriosis. The PFGE showed that the isolates were grouped in eight macrorestriction patterns (P1 to P8). A representative isolate of each macrorestriction pattern was investigated for the presence of virulence genes and all isolates carried the cadF, ciaB, cdtA, cdtB, cdtC, and flaA genes. The dnaJ gene was detected in 87.5% (7/8) of the isolates. The flhA and racR genes were detected in 75% (6/8), while the pldA gene was present in 62.5% (5/8) and the wlaN gene in 25% (2/8). The presence of C. jejuni in broiler farms and in the slaughterhouse is a hazard to consumer given that this pathogen can be maintained throughout the broiler production chain and contaminates the final product. Moreover, the presence of the major virulence genes in the isolates demonstrates that they have the ability to develop campylobacteriosis in humans.

Sixty-five strains of coagulase positive staphylococci (Staphylococcus aureus, S. intermedius and S. hyicus) were identified at species level by PCR amplification of the coa gene, specific for S. aureus, and of the nuc gene, specific for S. intermedius and for S. hyicus.

Contamination of industrial and domestic food usage environments by the attachement of bacterial food-borne pathogen Listeria monocytogenes has public health and economic implications. Comprehensive proteomics experiments using label-free liquid chromatography/tandem mass spectrometry were used to compare the proteomes of two different L. monocytogenes strains (Siliken_1/2c and F2365_4b), which show very different capacities to attach to surfaces. Growth temperature and strain type were highly influential on the proteomes in both attached and planktonic cells. On the basis of the proteomic data, it is highly unlikely that specific surface proteins play a direct role in adherence to inanimate surfaces. Instead, strain-dependent responses related to cell envelope polymer biosynthesis and stress response regulation likely contribute to a different ability to attach and also to survive external stressors. Collectively, the divergent proteome-level responses observed define strain- and growth-temperature-dependent differences relevant to attachment efficacy, highlight relevant proteins involved in stress protection in attached cells, and suggest that strain differences and growth conditions are important in relation to environmental persistence.

Staphylococcus aureus is an important pathogen of foodborne origin. The pathogen produces a variety of toxins that include the staphylococcal enterotoxins (SE). The present study aimed to evaluate the prevalence and expression of 5 SE genes (sea, seb, sec, sed, and see) in S. aureus isolated from outbreaks occurred in the state of Rio Grande do Sul, Brazil. All isolates, with the exception of 2, presented the same or higher transcriptional expression than the reference strains for at least 1 of these genes. The presence of SE genes combined with high levels of transcriptional expression suggests that 1 or more SEs were involved with the staphylococcal food poisoning outbreak analyzed in the present study.

Aspergillus westerdijkiae is a potent ochratoxin A (OTA) producer that has been found in coffee beans. OTA is known to have nephrotoxic effects and carcinogenic potential in animal species. Here we report for the first time the Agrobacterium-mediated transformation for Aspergillus westerdijkiae and the generation of ochratoxin-defective mutants. Conidia were transformed to hygromycin B resistance using strain AGL-1 of Agrobacterium tumefaciens. The obtained transformation frequency was up to 47 transformants per 10(6) target conidia. Among 600 transformants, approximately 5% showed morphological variations. Eight transformants with consistently reduced OTA production were obtained. Two of these transformants did not produce OTA (detection limit: 0.1 microg/kg); the other six mutants produced lower amounts of OTA (1%-32%) compared with the wild-type strain. By using thermal asymmetric interlaced polymerase chain reaction, we successfully identified a putative flavin adenine dinucleotide monooxygenase gene.

RESUMO -Staphylococcus aureus é, entre as espécies de estafilococos, a mais relacionada a infecções em animais e humanos, bem como a doenças de origem alimentar. Entretanto, S. intermedius e S. hyicus, duas espécies com características morfológicas muito similares a S. aureus, também podem causar doenças, bem como produzir enterotoxinas em alimentos, tornando importante a diferenciação entre essas três espécies de estafilococos. O objetivo deste trabalho foi avaliar a eficiência de oito técnicas bioquímicas com relação à sua capacidade para distinguir entre S. aureus, S. intermedius e S. hyicus. Para isso, 65 cepas, previamente identificadas em nível de espécie através de técnicas moleculares, foram submetidas aos testes de produção de pigmentos carotenóides, atividade hemolítica em ágar sangue, produção de β-galactosidase, produção de acetoína, atividade lipolítica em polisorbato, fermentação aeróbica da maltose, fermentação anaeróbica do manitol e crescimento em ágar Baird-Paker e ágar P suplementados com acriflavina.Verificou-se que os testes de sensibilidade a acriflavina e de produção de β-galactosidase apresentaram bom poder discriminatório, demonstrando serem os melhores testes bioquímicos para a diferenciação entre essas três espécies de estafilococos.Palavras-chave: S. aureus, S. intermedius, S. hyicus, diferenciação bioquímica.ABSTRACT -Among staphylococcus species, Staphylococcus aureus is the one mostly related to animal and human infections, as well as food diseases. However, S. intermedius and S. hyicus, two species with very similar morphological characteristics to S. aureus, can also cause diseases as well as produce enterotoxins in food, what makes important the differentiation of these three species. The aim of this work was to study the efficiency of eight biochemical techniques regarding their capacity to distinguish among S. aureus, S. intermedius and S. hyicus. For that purpose, sixty five strains, previously identified at species level through molecular techniques, were submitted to the tests of carotenoid pigments production, hemolytic activity in blood agar, β-galactosidase production, acetoin production, lipolytic activity in polysorbate, maltose aerobic fermentation, manitol anaerobic fermentation and growth in Baird-Parker and P agar supplemented with acriflavine. It was verified that tests of sensitivity to acriflavine and β-galactosidase production display good distinguishing properties, constituting as a whole, the best biochemical tests for the identification of these three staphylococcus species.