Antimicrobial resistance of Salmonella serotypes isolated from slaughter-age pigs and environmental samples

The aim of this study was to determine the antimicrobial resistance patterns of Salmonella strains isolated from slaughter-age pigs and environmental samples collected at modern swine raising facilities in Brazil. Seventeen isolates of six serotypes of Salmonella enterica subsp. enterica were isolated out of 1,026 collected samples: Salmonella Typhimurium (1), Salmonella Agona (5), Salmonella Sandiego (5), Salmonella Rissen (1), Salmonella Senftenberg (4), and Salmonella Javiana (1). Resistance patterns were determined to extended-spectrum penicillin (ampicillin), broad-spectrum cephalosporins (cefotaxime and ceftriaxone), aminoglycosides (streptomycin, neomycin, gentamicin, amikacin, and tobramycin), narrow-spectrum quinolone (nalidixic acid), broad-spectrum quinolone (ciprofloxacin and norfloxacin), tetracycline, trimethoprim, and chloramphenicol. Antimicrobial resistance patterns varied among serotypes, but isolates from a single serotype consistently showed the same resistance profile. All isolates were resistant to tetracycline, streptomycin, and nalidixic acid. One isolate, Salmonella Rissen, was also resistant to cefotaxime and tobramycin. All serotypes were susceptible to ceftriaxone, norfloxacin, ciprofloxacin, ampicillin, gentamicin, and chloramphenicol. The high resistance to tetracycline and streptomycin may be linked to their common use as therapeutic drugs on the tested farms. No relation was seen between nalidixic acid and fluoroquinolone resistance.

THE EFFECT OF CARBOHYDRATE ADMINISTRATION ON EXPERIMENTAL-INFECTION WITH SALMONELLA SEROTYPES IN CHICKENS

Carbohydrates and cultures of faecal microflora were administered to newly hatched chicks to prevent infection with Salmonella typhimurium Salmonella enteritidis, Salmonella agona and Salmonella infantis. Birds were killed 72 hours after challenge and the number of viable Salmonella organisms in their caecal contents estimated. Carbohydrates did not promote efficient control of infection with the Salmonella serotypes tested whereas cultures of faecal microflora completely prevented infection with all serotypes.

INTERFERENCE BETWEEN SALMONELLA SEROTYPES IN INTESTINAL COLONIZATION OF CHICKENS - CORRELATION WITH IN-VITRO BEHAVIOR

The effect of colonisation of the alimentary tract of newly hatched chicks by different Salmonella serotypes on the establishment in the gut by other Salmonella strains inoculated afterwards was assessed. Although profound inhibition of colonisation had been found previously to be genus-specific, considerable variation was found within the Salmonella genus. Some strains were found to be much more inhibitory than others and some were more easily inhibited than were others. There was not an absolute relationship between inhibitory activity and colonisation ability. No relationship was seen between inhibition and serotype or phage types within serotypes. There was no correlation between in vivo inhibition and the extent of inhibition that occurred in early stationary phase cultures in rich, undefined broth cultures.

SEROTYPES AND VIRULENCE OF SALMONELLA SP ISOLATED FROM FRESH-WATER

Twenty six Salmonella isolates of different serotypes were found in samples of fresh water. All 26 strains were checked for the presence of plasmids. Plasmids were found in eleven isolates. Four of the plasmid-containing strains and two of the plasmid-free strains were tested for invasiveness in mice. At least in the case of S. typhimurium, it seems reasonable to link virulence with plasmid harbouring.

Experimental infection of one-day-old chicks with Salmonella Serotypes Previously isolated from poultry facilities, wild birds, and swine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biofilms of Candida albicans serotypes A and B differ in their sensitivity to photodynamic therapy

Candida albicans is classified into different serotypes according to cell wall mannan composition and cell surface hydrophobicity. Since the effectiveness of photodynamic therapy (PDT) depends on the cell wall structure of microorganisms, the objective of this study was to compare the sensitivity of in vitro biofilms of C. albicans serotypes A and B to antimicrobial PDT. Reference strains of C. albicans serotype A (ATCC 36801) and serotype B (ATCC 36802) were used for the assays. A gallium-aluminum-arsenide laser (660 nm) was used as the light source and methylene blue (300 mu M) as the photosensitizer. After biofilm formation on the bottom of a 96-well microplate for 48 h, each Candida strain was submitted to assays: PDT consisting of laser and photosensitizer application (L + P+), laser application alone (L + P-), photosensitizer application alone (L-P+), and application of saline as control (L-P-). After treatment, biofilm cells were scraped off and transferred to tubes containing PBS. The content of the tubes was homogenized, diluted, and seeded onto Sabouraud agar plates to determine the number of colony-forming units (CFU/mL). The results were compared by analysis of variance and Tukey test (p < 0.05). The two strains studied were sensitive to PDT (L + P+), with a log reduction of 0.49 for serotype A and of 2.34 for serotype B. Laser application alone only reduced serotype B cells (0.53 log), and the use of the photosensitizer alone had no effect on the strains tested. It can be concluded that in vitro biofilms of C. albicans serotype B were more sensitive to PDT.

Padronização de três ELISAs polivalentes com lipopolissacarídeos de cadeia longa dos sorotipos 1 e 5, 2, 3 e 7 ou 10 e 12 de Actinobacillus pleuropneumoniae

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Requirement for cobalamin by Salmonella enterica serovars Typhimurium, Pullorum, Gallinarum and Enteritidis during infection in chickens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

UTILIZAÇÃO da PRÓPOLIS E ÁLCOOL ETÍLICO NO CONTROLE DE Salmonella em RAÇÕES AVÍCOLAS

Em quatro experimentos foram avaliados como agentes antibacterianos os produtos própolis em solução alcoólica e álcool etílico, adicionados às rações artificialmente contaminadas com os respectivos sorotipos: Salmonella typhimurium Nalr - Specr, (resistentes ao ácido Nalidíxico e a Spectinomicina) nos três primeiros experimentos e Salmonella agona Nalr - Specr, Salmonella infantis Nalr - Specr e Salmonella enteritidis Nalr - Specr no quarto experimento. As rações foram fornecidas a grupos de 10-16 pintos de corte de um dia. em todos os experimentos os produtos testados foram adicionados na base de 2% da ração. Quando se utilizou solução hidroalcóolica de própolis (exp. 1), seguidas 120 horas após o desafio, detectou-se a presença da bactéria nos cecos. No segundo experimento, testou-se a solução de própolis e seu diluente, o álcool etílico; seguidas 96 horas após o desafio, não foi observada a presença da bactéria nos cecos (< 2,0 log10). Avaliou-se, no terceiro experimento, a ação da solução de própolis e do álcool etílico no tempo, adicionados na ração 14 dias e 28 dias antes do fornecimento às aves. Após 72 horas do desafio, a leitura nas placas acusou a presença da bactéria nos cecos. Dentro deste último período, também se avaliou a ação da própolis em pó (extrato seco) e esse mesmo extrato em uma solução aquosa, adicionados à ração 48 horas antes do fornecimento às aves sendo que os resultados confirmaram a presença da bactéria nos cecos. No quarto experimento avaliou-se somente o álcool etílico nas rações artificialmente contaminadas com os sorotipos S. agona, S. enteritidis e S. infantis, registrando-se contagem zero (<2,0 log10) apenas com o último sorotipo. Os resultados obtidos permitem concluir que o tratamento com a solução de própolis apresentou ação sobre a S. typhimurium somente quando em solução alcóolica, dentro de um período de 48 horas, indicando que o efeito bactericida se deveu ao álcool etílico presente na solução. A ação do tratamento com o álcool etílico sobre os demais sorotipos demonstrou resultado parcial sendo observado efeito bactericida nos sorotipos S. typhimurium e S. enteritidis artificialmente inoculados na ração.

Chicken serologic response to Salmonella enterica serotype Typhimurium assessed by Elisa

This study evaluated two enzyme-linked immunosorbent assays (ELISA) in the detection of chicken serologic response against Salmonella enterica sorotype Typhimurium. The assays have used as detecting antigen the soluble bacterial proteins of a non-flagellated strain of Salmonella Typhimurium (AgTM), and antibody conjugated to peroxidase or alkaline phosphatase. According to the results, optimal dilutions of antigen (concentration 5.49 mg/mL) and serum samples in both assays were 1:20,000 and 1:1,000, respectively. In such conditions, the ELISA/AgTM was able to detect serological response to Salmonella Typhimurium. Cross-reactions to Salmonella serotypes Gallinarum and Pullorum were seen, but not with other serotypes such as Enteritidis.

Etiology of acute diarrhea among children in Ribeirão Preto-SP, Brazil

Com o objetivo de caracterizar os principais enteropatógenos causadores de diarréia na região de Ribeirão Preto, quanto aos sorogrupos e sorotipos, por um período de 4 anos foram estudadas fezes de 1836 crianças, menores de 10 anos de idade, de ambos os sexos, portadoras de gastrenterite aguda no IAL de Ribeirão Preto, SP. Foram pesquisados os seguintes enteropatógenos: Escherichia coli, Salmonella sp., Shigella sp., Campylobacter sp., Yersinia sp., e Cryptosporidium sp., identificados através de metodologia tradicional. Foram positivas 419 (22,8%) amostras, com 1,7% de associação entre enteropatógenos. Houve predomínio na faixa etária de 0 a 11 meses. Destacou-se a E.coli enteropatogênica (EPEC) (8,7%), sendo mais frequente o sorogrupo O119 (40,2%), seguida do gênero Shigella (6,2%), dos quais 63,2% corresponderam à S. sonnei.

Comparação de Meios de Enriquecimento e de Plaqueamento Utilizados na Pesquisa de Salmonella em Carcaças de Frango e Fezes de Aves

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Virulence properties and antimicrobial susceptibility of Shiga toxin-producing Escherichia coli strains isolated from healthy cattle from Parana State, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Control of Salmonella Enteritidis and Salmonella Gallinarum in birds by using live vaccine candidate containing attenuated Salmonella Gallinarum mutant strain

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Molecular differentiation of Salmonella Gallinarum and Salmonella Pullorum by RFLP of fliC gene from Brazilian isolates

Although Salmonella Pullorum and Salmonella Gallinarum cause different diseases in poultry, they are very similar. Both are non-motile and present the same somatic antigenic structure. They are differentiated by biochemical tests. Certain atypical strains are very difficult to distinguish. They do not produce the expected results when dulcitol and ornithine descarxboxylase tests are performed. Therefore, additional tests could be helpful. Many studies have chose the part I of the gene that encodes flagellin (fliC) to differentiate serotypes. Most Salmonella strains have two structural genes (fliC and fliB) that encode flagellins. Non-motile strains generally present these structural genes, but are not able to build a functional flagellum. It was demonstrated that enzymatic restriction of the amplified fliC gene using Hinp1I enzyme can differentiate SG from SP. In the present study, this method was adopted to analyze 14 SP and 22 SG strains, including some strains with atypical results in biochemical tests assessing the utilization of dulcitol and ornithine. The results showed that all SG strains were broken by the enzyme, whereas the 14 SP strains were not.