Impact of Extracellular DNA on Architectural Parameters of Leptospira biflexa Biofilm.

Extracellular DNA (eDNA) is a major component of bacterial biofilms. In this study, we performed a three-dimensional analysis of Leptospira biofilm using advanced imaging by confocal laser scanning microscopy (CLSM) and multi-parameter analysis by COMSTAT 2 software, with quantification of Leptospira and eDNA fluorescence. To investigate the role of eDNA in Leptospira biofilm, we treated Leptospira biflexa biofilms with DNase I enzyme (DNase), which digested eDNA, and compared DNase treated biofilms and controls. There was a significant reduction of the biomass of biofilms treated with DNase, by spectrophotometry and COMSTAT analysis. The multiparameter analysis evidenced for DNase-treated biofilms a significant decrease in the surface area and the average thickness; opposing to a significant augmentation of the surface/biovolume ratio and the roughness coefficient (Ra*), when compared to controls. We analyzed the parameters of DNase-treated biofilms by Pearson's correlation coefficient and found significant positive correlations between biomass and average thickness; biomass and surface area; surface area and average thickness. On the other hand, there were significant negative correlations between Ra* and biomass; Ra* and average thickness; Ra* and surface area. These findings suggest that eDNA digestion results in biofilm instability and alteration of the three-dimensional architecture, justifying the negative correlation between Ra* and the above-mentioned parameters. In conclusion, our study showed that eDNA digestion produced a massive structural loss, instability, and dramatic changes in the three-dimensional architecture of Leptospira biflexa biofilm. These findings contribute to a better understanding of the role of eDNA and highlight the importance of eDNA as a key component in Leptospira biofilms.

Hepatite granulomatosa em bovino causada por Mycobacterium avium subsp. paratuberculosis / Granulomatous hepatitis in cattle caused by Mycobacterium avium subsp. paratuberculosis

Samples from intestines, liver, and lymph nodes were collected from a dairy steer with clinical suspicion of paratuberculosis. The samples were processed for histologic examination with hematoxylin-eosin and Zihel-Neelsen (ZN) staining for the detection of acid-fast bacilli (AFB), and submitted to immunohistochemistry (IHC). Macroscopic changes were observed in the small intestines, with thickening and corrugation of the mucosa. The main microscopic changes were found in small intestines, lymph vessels in the mesentery, and mesenteric lymph nodes characterized by enteritis, lymphangiectasia, and lymphadenitis. Liver presented with granulomatous hepatitis, an uncommon histopathological feature for paratuberculosis. The clinical features associated with positive culture of Mycobacterium avium subsp. paratuberculosis and detection of AFB by ZN and IHC in the cytoplasm of macrophages (epithelioid) in the intestinal mucosa and submucosa, lymph nodes, and liver were important to confirm the diagnosis of paratuberculosis.

Identification of Leptospira spp. carriers among seroreactive goats and sheep by polymerase chain reaction.

Few studies were conducted on the diagnosis and control of small ruminants' leptospirosis. Thirteen goat herds and seven sheep flocks located in the state of Rio de Janeiro, Brazil, were screened for leptospirosis. From the three herds and three flocks with greatest seroreactivity by MAT (Microscopic Agglutination Test), 19 and 40 seropositive goats and sheep, respectively, were selected, and urine samples were collected for bacteriology and PCR. For both species of animals, the most prevalent reactions were due to serogroups Sejroe and Shermani. Although leptospires were observed by darkfield microscopy in eight samples, pure isolates were obtained by bacteriological culture from only two samples. However, twelve urine samples (six goats and six sheep) were positive by PCR. Based on these findings, we consider that the combined use of MAT as a screening test followed by urine PCR for the direct detection of Leptospira spp. DNA was adequate for the identification of carrier animals among goats and sheep. These are valuable tools for the control of leptospirosis in small ruminants.

Leptospirosis antibodies in mammals from Rio de Janeiro Zoo, Brazil.

Serum samples from 77 animals belonging to 38 species and 19 families in Rio de Janeiro Zoo, Brazil were tested for antibodies against serovars of Leptospira interrogans by microscopic agglutination test. Antibodies were detected in serum samples of 37.7% of all animals belonging to 10 families. Seropositivity was more common in the Carnivora Canidae (7/9), Procyonidae (5/9) and the Edentata Myrmecophagidae (5/9). Icterohaemorrhagiae was the most common serogroup. Seropositivity was less common in primates.

Formas de exploraçäo do rebanho caprino no Estado do Rio de Janeiro, 1998/2000 / Goat industry in the State of Rio de Janeiro, 1998/2000

Aiming to understanding the goat industry in the State of Rio de Janeiro, from 1998-2000, this study was carried out in 48 goat farms, 72.9 percent of which with an area of less than eight hectares. Also, 62.5 percent of the farms had irregular topography, and 69 percent of them kept Saanen breed in a confined system (93.7 percent). Animals were housed between 16 to 24 hours/day in suspended wooden stalls, and 83.3 percent were dairy goats