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

Mutations into codons Aspartate-87 (62%) and Serine-83 (38%) 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% was contaminated with termotolerant Campylobacter spp. with average count of 3.08 Log10 CFU/g on direct plating. After refrigeration, 53.3% of the analyzed samples tested positive for Campylobacter and the average count was 1.19 Log10 CFU/g. After storage at -20ºC, 36.6% of the samples were positive with a verage count of 0.75 Log10 CFU/g. C. jejuni was detected after enrichment, respectively, in 50% of the fresh, 36.7% of the refrigerated and 33.3% 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.

Staphylococci: colonies morphological caracteristics, coagulase and EEA production colected from cooled raw milk samples / Estafilococos: morfologia das colônias, produção de coagulase e enterotoxina a, em amostras isoladas de leite cru refrigerado

The stories of food poisoning from staphylococci, mainly by S. aureus, are frequently associates to the ingestion of food with 100 ng of enterotoxin/g or mL. The production of enterotoxin using staphylococci is strongly associated with the production of coagulase. In this paper, milk samples of 51 milk properties in Londrina (RS) and 50 in Pelotas had been evaluated. All the 101 samples had presented counts of coagulase positive staphylococci (CPS). From 552 colonies studied, 256 were CPS where 60% of the colonies were typical in Baird Parker agar and, from 296 coagulase negative staphylococcus (CNS), in mean, 60% were atypical colonies. Due to the enterotoxigenic capacity, were tested 109 CPS, being 5,5% (6) positive and 18 CNS where 1 (5,5%) were positive. The frequency of CPS EEA (5,5%) producer was similar of the CNS. There is a wide milk contamination with CPS, where, a big part (40%) of the atypical colonies is coagulase producers.

Os relatos de intoxicação estafilocócica, principalmente por S. aureus, são frequentemente associados à ingestão de 100 ng de enterotoxina/g ou mL de alimento. A produção de enterotoxina pelos estafilococos está associada fortemente à produção de coagulase. Neste trabalho foram avaliadas amostras de leite de 51 propriedades leiteiras em Londrina (RS) e 50 em Pelotas. Todas as 101 amostras apresentaram contagens de estafilococos coagulase positivos (ECP). Das 552 colônias avaliadas, 256 foram coagulase positivas e destas cerca de 60% eram típicas no àgar Baird Parker e, em média, 60% do total de 296 estafilococos coagulase negativos (ECN) eram colônias atípicas. Quanto à capacidade enterotoxigênica, testou-se 109 colônias ECP, sendo 5,5% (6) positivas e 18 ECN, sendo 1 (5,5%) positiva. Assim, a freqüência de ECN produtores de EEA (5,5%) foi semelhante a dos ECP. Conclui-se que há extensa contaminação do leite cru por ECP, sendo grande parte (40%) das colônias atípicas produtoras de coagulase.