Detection of quinolone-resistance mutations in Salmonella spp. strains of epidemic and poultry origin

Mutations into codons Aspartate-87 (62 percent) and Serine-83 (38 percent) in QRDR of gyrA were identified in 105 Salmonella strains resistant to nalidixic acid (94 epidemic and 11 of poultry origin). The results show a high incidence of mutations associated to quinolone resistance but suggest association with others mechanisms of resistance.

Effect of refrigeration and frozen storage on the campylobacter jejuni recovery from naturally contaminated broiler carcasses

Campylobacter jejuni is the most common thermophilic Campylobacter associated with human enteritis in many countries. Broilers and their by-products are the main sources for human enteritis. Refrigeration and freezing are used to control bacterial growth in foods. The effect of these interventions on survival of Campylobacter jejuni is yet not quite understood. This study evaluated the effect of storage temperature on the survival of C. jejuni in chicken meat stored for seven days at 4ºC and for 28 days at -20ºC. The influence of selective enrichment on recovery of Campylobacter was also evaluated. Thirty fresh chicken meat samples were analyzed and 93.3 percent was contaminated with termotolerant Campylobacter spp. with average count of 3.08 Log10 CFU/g on direct plating. After refrigeration, 53.3 percent of the analyzed samples tested positive for Campylobacter and the average count was 1.19 Log10 CFU/g. After storage at -20ºC, 36.6 percent of the samples were positive with a verage count of 0.75 Log10 CFU/g. C. jejuni was detected after enrichment, respectively, in 50 percent of the fresh, 36.7 percent of the refrigerated and 33.3 percent of the frozen meat samples analyzed. No difference was detected for the recovery of C. jejuni from fresh, refrigerated or frozen samples after selective enrichment, showing that this microorganism can survive under the tested storage conditions.

Produção e purificação de anticorpos policlonais para Salmonella Enteritidis (Enterobacteriaceae) / Production and purification of polyclonal antibodies for Salmonella Enteritidis (Enterobacteriaceae)

O objetivo deste trabalho foi produzir e purificar anticorpos policlonais específicos para Salmonella Enteritidis (Enterobacteriaceae). O anti-soro foi produzido em coelhos, empregando-se flagelina purificada. O título e a especificidade foram determinados através do ensaio imunoenzimático - ELISA e a purificação por cromatografia de afinidade com sepharose Proteína A. As suspensões bacterianas foram cultivadas em cinco diferentes meios de cultura (infusão de cérebro coração - BHI, caldo tripticase soja, caldo lactosado, caldo nutriente - CN e água peptonada). Observou-se que dependendo do meio o título do anti-soro pode variar e os melhores resultados foram obtidos com BHI e CN. O anti-soro foi específico para Salmonella Enteritidis, apresentando porcentagens de reações cruzadas com Salmonella Typhimurium, Salmonella Infantis e Salmonella Newport de 16,0, 11,9 e 6,4 por cento, respectivamente. Menores porcentagens foram obtidas com outras enterobactérias testadas. Esses resultados indicam a possibilidade da utilização desses anticorpos na padronização de ensaios imunológicos para a detecção de Salmonella Enteritidis

Low cost production and purification of polyclonal antibodies to staphylococcal enterotoxin A

An immunization scheme for production of antiserum to staphylococcal enterotoxin A (SEA) is proposed. The reference method of Robbins and Bergdoll was modified to reduce the number of doses and the amount of toxin used per animal. The best immunization scheme used injections in days 0,8,24,59,62 and 67. The amount of toxin at each injection was 5,6,20,50,100 and 200ug, respectively. The total amount of toxin was 381ug, which corresponded to a reduction of 107ug in the amount of toxin for each animal when compared to the reference method. The average antiserum titer using the Optimum Sensitivity Plate - OSP was 1:60 and using ELISA the titer was 1:100.000. The lack of cross-reactivity with other staphylococcal enterotoxins indicated high specificity of the antibody to SEA. The proposed immunization scheme was adequate to produce specific SEA antisera, with high titers and the aditional advantage of reducing the amount of purified SEA required for immunization.