Genetic diversity of Streptococcus suis serotype 2 isolated from pigs in Brazil.

Streptococcus suis is an emerging zoonotic pathogen that causes septicemia, meningitis, arthritis, and pneumonia in swine and humans. The present study aimed to characterize the genetic diversity of S. suis serotype 2 isolated from pigs showing signs of illness in Brazil using pulsed-field gel electrophoresis (PFGE), single-enzyme amplified fragment length polymorphism (SE-AFLP), and profiling of virulence-associated markers. A total of 110 isolates were studied, 62.7% of which were isolated from the central nervous system and 19.1% from the respiratory tract. Eight genotypes were obtained from the combination of virulence genes, with 43.6% and 5.5% frequencies for the mrp (+) /epf (+) /sly (+) and mrp (-) /epf (-) /sly (-) genotypes, respectively. The presence of isolates with epf gene variation with higher molecular weight also appears to be a characteristic of Brazilian S. suis serotype 2. The PFGE and SE-AFLP were able to type all isolates and, although they presented a slight tendency to cluster according to state and year of isolation, it was also evident the grouping of different herds in the same PFGE subtype and the existence of isolates originated from the same herd classified into distinct subtypes. No further correlation between the isolation sites and mrp/epf/sly genotypes was observed.

Streptococcus suis est un agent pathogène zoonotique en émergence responsable de septicémies, des méningites, d'arthrites, et de pneumonies chez les porcs et les humains. La présente étude visait à caractériser la diversité génétique de souches de S. suis sérotype 2 isolées au Brésil de porcs montrant des signes de maladie à l'aide des techniques suivantes : électrophorèse en champs pulsés (PFGE), polymorphisme des fragments amplifiés par un enzyme unique (SE-AFLP), et profilage des marqueurs de virulence. Un total de 110 isolats a été étudié, 62,7 % isolats provenant du système nerveux central et 19,1 % du tractus respiratoire. Huit génotypes furent obtenus de la combinaison de gènes de virulence, avec des fréquences de 43,6 % et 5,5 % pour les génotypes mrp+/epf+/sly+ et mrp−/epf−/sly−, respectivement. La présence d'isolats avec la variation du gène epf et un poids moléculaire plus élevé semble être également une caractéristique de S. suis sérotype 2 d'origine brésilienne. Les méthodes PFGE et SE-AFLP ont été en mesure de permettre le typage de tous les isolats et, bien qu'il y avait une légère tendance à se regrouper selon l'état et l'année d'isolement, il était également évident qu'il y avait du regroupement d'isolats provenant de différents troupeaux dans le même sous-type de PFGE et de l'existence d'isolats provenant du même troupeau classifiés dans des sous-types différents. Aucune autre corrélation entre le site d'isolement et les génotypes de mrp/epf/sly ne fut observée.(Traduit par Docteur Serge Messier).

Experimental leptospirosis in capybaras (Hydrochaeris hydrochaeris) infected with Leptospira interrogans serovar Pomona.

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 (10(9)-10(11) organisms, given i.v.), peaked (titer, approximately 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.

Comparative efficacy of two single-dose bacterins in the control of Mycoplasma hyopneumoniae in swine raised under commercial conditions in Brazil.

A field study was conducted in Brazil to evaluate the efficacy of single vaccination of pigs with two bacterins to prevent Mycoplasma hyopneumoniae lung lesions. The first (T1) treatment group (174 pigs) was injected with 2 mL of saline solution; group T2 (177 pigs) with 2 mL of bacterin A, and group T3 (174 pigs) with 2 mL of bacterin B. On days-on-test (DOT) 0, 35, 66, 97 and 125, blood samples and tonsil swabs were collected from selected pigs for antibody determination (indirect ELISA) and PCR assay for the presence of M. hyopneumoniae. Pigs were slaughtered on DOT 126-129 and lung lesions were scored blindly. Bacterin A vaccinated pigs had significantly (P < or = 0.05) lower lung lesion scores (0.2%) than bacterin B (0.4%) or saline-treated pigs (1.2%); there was also a significantly lower (P < or = 0.05) number of pigs with lung lesions (27.1%), than bacterin B (38.2%) or saline-treated (55.4%) pigs. The two vaccines had similar (P>0.05) results in terms of mean weight gain, average daily weight gain, feed efficiency, frequency of PCR positives, and there was similar antibody conversion (ELISA). It was concluded that although the productivity parameters and antibody conversions were similar, bacterin A was more effective in preventing and reducing the severity of lung lesions than bacterin B.