TSST-1, enterotoxin and bacteriocin-like substance production by Staphylococcus aureus isolated from foods / TSST-1, enterotoxinas e substâncias tipo bacteriocina produzidas por Staphylococcus aureus isolados de alimentos

The production of Toxic Shock Syndrome Toxin-1 (TSST-1), enterotoxins and bacteriocin-like substances was evaluated in 95 strains of Staphylococcus aureus recovered from raw bovine milk (n=31) and from food samples involved in staphylococcal food poisoning (n=64). Enterotoxigenicity tests with the membrane over agar associated to optimal sensibility plate assays were performed and showed that 96.77% of strains recovered from milk and 95.31% from food samples produced enterotoxins A, B, C, D or TSST-1. Reference strains S. epidermidis, Bacillus cereus, Listeria monocytogenes, Lactobacillus casei, Pseudomonas aeruginosa, S. aureus, Salmonella Typhimurium, Escherichia coli, Enterococcus faecalis and Bacteroides fragilis were used as indicator bacteria in the antagonistic assays, the first five being sensitive to antagonistic substances. Brain heart infusion agar, in pH values ranging from 5.0 to 7.0 in aerobic atmosphere showed to be the optimum condition for antagonistic activity as evaluated with the best producer strains against the most sensitive indicator bacterium, L. monocytogenes. Sensitivity to enzymes confirmed the proteinaceous nature of these substances. Neither bacteriophage activity nor fatty acids were detected and the antagonistic activity was not due to residual chloroform. Results did not establish a positive correlation between the bacteriocinogenic profile and toxigenicity in the tested S. aureus strains.

Avaliou-se a produção de toxina-1 da síndrome do choque tóxico (TSST-1), enterotoxinas e substâncias antagonistas tipo bacteriocina em 95 amostras de Staphylococcus aureus recuperadas de leite bovino in natura (n=31) e de alimentos envolvidos em surto de intoxicação (n=64). Testes de enterotoxigenicidade pelo método da membrana sobre ágar, associado à técnica da sensibilidade ótima em placa, revelaram que 96,77% das amostras do leite e 95,31% daquelas dos alimentos produziram enterotoxinas estafilocócicas tipos A, B, C, D ou TSST-1. Nos ensaios de antagonismo, foram utilizadas como reveladoras amostras de referência de S. epidermidis, Bacillus cereus, Listeria monocytogenes, Lactobacillus casei, Pseudomonas aeruginosa, S. aureus, Salmonella typhimurium, Escherichia coli, Enterococcus faecalis e Bacteroides fragilis, sendo as cinco primeiras sensíveis às substâncias produzidas. As condições ótimas para a atividade antagonista, avaliadas com as melhores produtoras contra a indicadora mais sensível, L. monocytogenes, foram observadas em aerobiose, em ágar infuso de cérebro-coração, nos valores de pH entre 5,0 e 7,0. A sensibilidade a enzimas confirmou a natureza proteica destas substâncias. Não foram detectadas atividades de bacteriófagos nem de ácidos graxos, e a atividade antagonista não foi devido ao clorofórmio residual. Os resultados não mostraram correlação entre o perfil bacteriocinogênico e a toxigenicidade nas amostras de Staphylococcus testadas.

Identification and in vitro production of Lactobacillus antagonists from women with or without bacterial vaginosis

Lactobacilli isolated from the vaginal tract of women with and without bacterial vaginosis (BV) were identified and characterized for the production of antagonists. Bacterial samples were isolated from healthy women (N = 16), from patients with clinical complaints but without BV (N = 30), and from patients with BV (N = 32). Identification was performed using amplified ribosomal DNA restriction analysis. Production of antagonistic compounds was evaluated by the double-layer diffusion technique using Gram-positive (N = 9) and Gram-negative bacteria (N = 6) as well as yeast (N = 5) as indicator strains. Of a total of 147 isolates, 133 were identified as pertaining to the genus Lactobacillus. Lactobacillus crispatus was the species most frequently recovered, followed by L. johnsonii and L. jensenii. Statistical analysis showed that L. crispatus was more frequent in individuals without BV (P < 0.05). A higher production of antagonists was noted in L. crispatus isolates from healthy women (P < 0.05). More acidic local pH and higher H2O2 production by isolated lactobacilli from healthy women suggest these mechanisms as the possible cause of this antagonism. In conclusion, a significant correlation was detected between the presence and antagonistic properties of certain species of Lactobacillus and the clinical status of the patients.

External skeletal fixation in dogs: clinical and microbiological avaluation

Eleven dogs, of both sexes, average weight of 12kg, with ages ranging from two to five years were used with the objective of evaluating two treatments of skin wounds produced after percutaneous bone transfixation of the tibia. In six animals, cotton swabs embedded in 0.2 per cent iodine-alcohol were used to clean the areas of pin perforations. In five dogs, a 0.9 per cent sodium chloride solution, under approximate 30 psi pulse pressure, was used. In both cases, and treatments were carried out every three to four days, during four weeks. Clinical specimens were collected under anaerobic conditions, immediately before the treatments, and on days 3, 7, 14 and 28 after surgery. Samples were cultured in specific media in order to allow isolation of aerobic and anaerobic bacteria and yeast. Dogs treated with sodium chloride solution showed little purulent exudation, while dogs treated with iodine-alcohol presented dry skin wounds with minimum blood-serous to serous exudation. The microbiological evaluation revealed predominance of Staphylococcus spp, but no differences were observed between the two treatments. The results allowed to conclude that both methods are efficient for post-surgical treatments of bone percutaneous transfixation in dogs