RESUMO
A transmissão de Salmonella na cadeia produtiva de suínos é um problema de difícil controle. O objetivo do estudo foi avaliar o efeito da administração oral de probiótico sobre a ocorrência de infecção e excreção fecal de Salmonella em suínos em fase de crescimento. Os tratamentos consistiram de ração basal sem aditivos (controle) ou adicionada de probiótico (10(7)ufc g-1 de células viáveis dos gêneros Bifidobacterium, Enterococcus, Lactobacillus e Saccharomyces). Foram alocados seis leitões de 50 dias em cada tratamento, com duas repetições por tratamento. Todos os animais foram inoculados com Salmonella Typhimurium (10(6)ufc mL-1) após 14 dias do alojamento. Semanalmente, foram coletadas amostras de sangue e fezes e no dia 35 pós-inoculação os animais foram sacrificados e necropsiados. Os animais de ambos os tratamentos foram infectados por Salmonella e soroconverteram. Não houve diferença (P>0,05) entre os grupos nas médias de Salmonella, Enterococcus, Lactobacillus e coliformes totais nas fezes, porém a administração de probiótico resultou em menor frequência de isolamento de Salmonella a partir de fígado (P=0,04), linfonodos mesentéricos (P=0,04), pulmão (P=0,03) e baço (P=0,01). Conclui-se que os microrganismos probióticos testados não foram capazes de impedir a infecção ou a excreção fecal de Salmonella em suínos de crescimento, mas diminuíram o número de portadores em linfonodos mesentéricos.
Control of Salmonella transmission has been a challenge for the pork production companies. The aim of this study was to evaluate the effect of oral administration of probiotics on the occurrence of infection and fecal excretion of Salmonella in growers. The treatments consisted of basal diet without additives (control) or added of probiotic (10(7)cfu g-1 of viable cells of the genera Bifidobacterium, Enterococcus, Lactobacillus and Saccharomyces). Six 50 days-old pigs were allocated into each treatment, with two replicates per treatment. All animals were inoculated with Salmonella Typhimurium (10(6)cfu mL-1) after 14 days of housing. Afterwards, blood and feces samples were taken weekly and on day 35 post-inoculation the animals were euthanized and necropsied. The animals in both treatment groups were infected by Salmonella and seroconverted. There was no difference (P>0.05) between groups in mean counts of Salmonella, Enterococcus, Lactobacillus and coliforms in the feces samples, but the probiotic administration resulted in a lower frequency of isolation of Salmonella from liver (P=0.04), mesenteric lymph nodes (P=0.04), lung (P=0.03) and spleen (P=0.01). It was concluded that the probiotic microorganisms tested in this study were not able to protect against the infection or to decrease the fecal excretion of Salmonella in growing pigs, but were able to decrease the number of carriers in the mesenteric lymph nodes.
RESUMO
Swine can carry Salmonella strains that may be transmitted to humans by pork products. This investigation determined the distribution and types of Salmonella in 12 swine finishing herds and a slaughter facility in Santa Catarina, Brazil. A total of 1258 samples, consisting of environmental, feed, carcass, lymph node, and fecal material were collected and submitted to bacteriological isolation of Salmonella. From 487 positive samples, 1255 isolates were recovered and confirmed to be Salmonella. The distribution of positive samples was as follows: finishing pen floors 26% (16/61); feed 29% (42/143); feces 44% (52/119); pooled feces 59% (35/59); slaughter holding pens 90% (36/40); lymph nodes 46% (220/478); pre-chilled carcass surfaces 24% (24/98); and post-chilled carcass surfaces 24% (62/260). The most prevalent serovars were Typhimurium, Panama, Senftenberg, Derby, and Mbandaka. By pulsed-field gel electrophoresis, 1071 isolates were subtyped using XbaI, and duplicate isolates were removed. From the remaining 747 isolates, 163 macrorestriction profiles (pulsotypes) were identified. Six pulsotypes were considered very frequent, occurring in 33 isolates or more. The multiple correspondence analyses showed correlations between pulsotypes from shedding pigs (feces), herd environment (pen floors), and subiliac and prescapular lymph nodes and between lairage and carcass surface samples before and after chilling. All sources of Salmonella investigated contributed to the carrier state; however, pre-slaughter contamination at lairage was the variable most strongly associated with carcass contamination. A total of 59 different antimicrobial resistance profiles were observed in 572 Salmonella isolates. From these isolates, 17% (97/572) were susceptible to all 15 antibiotics tested, 83% (475/572) were resistant to at least one, and 43% (246/572) were resistant to four or more antibiotics (multi-resistant). The AmpGenKanTet profile was the most prevalent in carcass isolates and was associated with farm origin.
