Maria Regina Baccaro

Virulence properties of Escherichia coli isolated from ostriches with respiratory disease.

Eight Escherichia coli isolates from ostriches with respiratory disease were investigated for the presence of genes encoding the following adhesins: type 1 pili (fim), pili associated with pyelonephritis (pap), S fimbriae (sfa), afimbrial adhesin (afaI), temperature regulated adhesin, curli (crl, csgA) and temperature-sensitive hemagglutinin (tsh). Genes for heat labile (LT) and heat stable (STa and STb) enterotoxins, Shiga toxins (stx1 and stx2), cytotoxic necrotizing factor 1 (cnf), alpha-haemolysin (hly) and aerobactin (aer) production were also investigated. Other characteristics investigated were the presence of hemagglutination activity, growth on an iron-deficient medium, aerobactin production, serum resistance, adherence to chicken tracheal cells, pathogenicity for day-old chicks, and serogroup. Serogrouping showed that four isolates belonged to serogroup O2, two to serogroup O78, one to serogroup O9, and one to serogroup O21. The virulence genes found were: fim in all eight isolates, csgA in seven, aer in six, and pap, crl and tsh in one isolate each. All isolates analyzed were positive for mannose-resistant hemagglutination, adhered in vitro to ciliated tracheal epithelium, grew on iron-deficient medium, and showed serum resistance. Pathogenicity tests on day-old chickens revealed one highly pathogenic isolate, three of low pathogenicity and four isolates with intermediate pathogenicity.

Experimental Leptospirosis in Capybaras (Hydrochaeris hydrochaeris) Infected with Leptospira interrogans Serovar Pomona

Abstract Capybara (Hydrochaeris hydrochaeris), the largest rodent in the world, is widely distributed in South America. These animals live in areas with abundant water, which makes them a potential reservoir for Leptospira. The objective of this study was to investigate seroconversion, leptospiremia, and leptospiruria in capybaras experimentally infected with a virulent strain of Leptospira interrogans serovar Pomona. Seven capybaras were used: one control and six infected. Agglutinins against serovar Pomona were initially detected in serum 6 or 7 day after innoculation with Leptospira (109–1011 organisms, given i.v.), peaked (titer, ∼3,200) between 9 and 27 day, and were still present at 83 day (end of study). The earliest and latest isolation of leptospires from the blood was from 2–12 day and from urine, 9–19 day after exposure. However, polymerase chain reaction and isolation results from kidney and liver samples were negative for leptospires. The control animal tested negative on all diagnostic tests. Hence, the capybara can serve as a host for Leptospira.

Identification of bacterial agents of enteric diseases by multiplex PCR in growing-finishing pigs

In Brazil, the most common bacterial enteric diseases affecting growing and finishing pigs are porcine proliferative enteritis, porcine intestinal spirochetosis, swine dysentery, and salmonellosis. The diagnosis of these diseases by routine culture techniques is expensive, difficult, time-consuming, and even impossible, in cases of porcine proliferative enteritis. The detection of pathogens by polymerase chain reaction is a highly sensitive and specific method that can be an useful tool in veterinary diagnosis. Two multiplex PCR (M-PCR) assays were tested for simultaneous detection and identification of bacterial agents associated with porcine proliferative enteritis, porcine intestinal spirochetosis, swine dysentery, and salmonellosis in diarrheic fecal samples. The DNA obtained from pure cultures of each bacterial agent or mixed in different combinations and concentrations was amplified by using Lawsonia intracellularis and Salmonella, or Brachyspira pilosicoli and Brachyspira hyodysenteriae specific M-PCR assays. After electrophoresis in agarose gel and staining, the amplification products indicated the presence of individual or simultaneous amplification of L. intracellularis and Salmonella or B. pilosicoli and B. hyodysenteriae specific DNA sequences. After standardization, the M-PCR tests were used to test 541 swine diarrheic fecal samples obtained from different regions in Brazil. The most frequently detected pathogen was Lawsonia intracellularis (13%), followed by Salmonella (4.8%), B. hyodysenteriae (1.4%), B. pilosicoli (1%) and their various associations. Results from this study suggest that the two M-PCR assays can be used for specific detection and identification of four important enteric bacterial pathogens alone or in combination.

Eficácia de vacina inativada contra a doença de Aujeszky: infecção experimental de suínos

Uma vacina experimental contra a doenca de Aujeszky (DA), inativada e adsorvida em adjuvante oleoso, foi testada em relacao a inducao de imunidade, grau de protecao clinica e capacidade de reduzir a infeccao, apos desafio pela via intranasal. Grupos de 6 suinos, com 45 dias de idade, foram vacinados com uma ou duas doses de vacina, pelas vias intramuscular ou subcutânea, sendo mantido um grupo-testemunha, sem vacinacao. Todos os suinos vacinados apresentaram titulos de anticorpos neutralizantes, detectaveis atraves da prova de soroneutralizacao, sendo estatisticamente superiores nos animais que receberam duas doses de vacina. A vacinacao preveniu as manifestacoes clinicas da doenca, apos desafio, principalmente nos animais que receberam duas doses de vacina quando comparado com os que receberam 1 dose. Em todos os animais, vacinados e nao-vacinados, foi possivel a deteccao do virus da doenca de Aujeszky (VDA) nas amigdalas, atraves da tecnica de imunofluorescencia direta. A porcentagem de amigdalas positivas nos suinos vacinados com duas doses foi inferior quando comparada aquela de suinos nao-vacinados, no 2o e 7o dias pos-infeccao. Em suinos vacinados com duas doses de vacina, pela via subcutânea, a taxa de infeccao foi estatisticamente menor que naqueles vacinados com uma dose, pelas vias intramuscular ou subcutânea, e nao-vacinados.

Use of single-enzyme amplified fragment length polymorphism for typing Clostridium perfringens isolated from diarrheic piglets

Clostridium perfringens is an important pathogen in human and veterinary medicine. In swine, the agent is responsible for necrotic enteritis and enterotoxemia characterized by diarrhea, weight loss, delayed development and, in some cases, death. In the present study amplified fragment length polymorphism analyses (AFLP) was used to characterize 54 C. perfringens strains isolated from swine presenting diarrhea. Analysis of the results showed 29 distinct profiles with discriminatory index equal to 0.97. Partial correlation between the origin of the isolates and groups was drawn, and correlation was possible in only 18.5% of the samples. Characterization of the strains in biotypes (A, B, C, D and E), production of beta-2 toxin and enterotoxin were performed by means of the polymerase chain reaction (PCR). Biotypes A, C and D were observed among the strains analyzed. All samples were positive for presence of the gene encoding beta-2 toxin and negative for the gene encoding enterotoxin. AFLP have shown to be a simple, fast, low cost method with high discriminative power and good reproducibility, presenting a great potential in epidemiological studies involving C. perfringens strains of animal origin.

Lethal Factor to Mice Produced by Escherichia coli Isolated from Chickens with Swollen Head Syndrome

A lethal toxin similar to Bacillus cererus lethal toxin was detected in the culture supernatants of Escherichia coli isolated from chickens with swollen head syndrome. The lethal activity was heat‐labile, protease‐sensitive and killed mice within 10 min. The light microscopy of the histopathological studies revealed that the principal organ affected by this toxin was the lung but the liver and kidneys also showed lesions. The relevance of this lethal activity from E. coli remains to be determined.

Histopathological and ultrastructural characteristics of myeloid leukosis in broiler chicken

An ultrastructural and histological study was performed to determine the degree of differentiation of the neoplastic cells. The histological study revealed neoplastic cells with pleomorphism, oval nuclei, prominent nucleoli, irregularly distributed chromatin, atypical mitotic figures and moderate amount of cytoplasm containing spherical eosinophilic granulations, typical features of the myeloid lineage. Ultrastructurally, there were cells with an electron-dense, oval and voluminous nucleus, with predominant euchromatin and cytoplasm containing many spherical, electron-dense and homogeneous granules, indicative of myelocytes with differentiation to eosinophils. Type-C viral particles were also seen in the intercellular space of renal tubules and inside the intracytoplasmic vesicles of immature myelocytes in the bone marrow and ovary. PCR was positive to ALV-J.