Bacillus cereus infection outbreak in captive psittacines.

This study reports an uncommon epizootic outbreak of Bacillus cereus that caused the sudden death of 12 psittacines belonging to the species Anodorhynchus hyacinthinus (1 individual), Diopsittaca nobilis (1 individual), Ara severa (1 individual) and Ara ararauna (9 individuals) in a Brazilian zoo. Post-mortem examination of the animals reveled extensive areas of lung hemorrhage, hepatic congestion, hemorrhagic enteritis and cardiac congestion. Histopathological examination of the organs showed the presence of multiple foci of vegetative cells of Gram-positive bacilli associated with discrete and moderate mononuclear inflammatory cell infiltrate. Seventeen B. cereus strains isolated from blood and sterile organs of nine A. ararauna were analyzed in order to investigate the genetic diversity (assessed by Rep-PCR) and toxigenic profiles (presence of hblA, hblC and hblD; nheA, nheB and nheC as well as cytK, ces and entFM genes) of such strains. Amplification of genomic DNA by Rep-PCR of B. cereus strains generated two closely related profiles (Rep-PCR types A and B) with three bands of difference. All strains were classified as belonging to the toxigenic profile I which contained HBL and NHE gene complexes, entFM and cytK genes. Altogether, microbiological and histopathological findings and the evidence provided by the success of the antibiotic prophylaxis, corroborate that B. cereus was the causative agent of the infection that killed the birds.

Phenotypic and genotypic features of new autoagglutinating Bacillus thuringiensis strains.

A total of 28 autoagglutinating strains of Bacillus thuringiensis were isolated from different ecologic niches and distinct sites. Twenty-six strains demonstrated toxicity to mosquito larvae of Aedes aegypti and Culex quinquefasciatus. The electrophoretic protein profiles of the crystal components were studied. Twenty-three out of the 28 strains showed the same larvicidal activity and the same protein profiles as B. thuringiensis serovar israelensis. Using isoenzyme analysis (MLEE), it was observed the presence of three electrophoretic types (ETs). The mosquitocidal strains grouped into one ET. The random amplified polymorphic DNA analysis (RAPD) was evaluated using six primers, which demonstrated three different patterns for the 28 autoagglutinating strains, allowing correlation of the profiles obtained with the toxicity observed in the bioassays. The RAPD patterns for mosquitocidal strains were identical to the one of serovar israelensis. However, to strains of low toxicity, each primer generated distinctive RAPD patterns, which demonstrated that these strains belong to different serovars. Although the antigenic classification the 26 autoagglutinating strains of B. thuringiensis could not be determined by classical flagellar serotyping, MLEE and RAPD profiles proved these strains to be compatible with B. thuringiensis serovar israelensis.

Histopathological and ultrastructural effects of delta-endotoxins of Bacillus thuringiensis serovar israelensis in the midgut of Simulium pertinax larvae (Diptera, Simuliidae).

The bacterium Bacillus thuringiensis (Bt) produces parasporal crystals containing delta-endotoxins responsible for selective insecticidal activity on larvae. Upon ingestion, these crystals are solubilized in the midgut lumen and converted into active toxins that bind to receptors present on the microvilli causing serious damage to the epithelial columnar cells. We investigated the effect of these endotoxins on larvae of the Simulium pertinax, a common black fly in Brazil, using several concentrations during 4 h of the serovar israelensis strain IPS-82 (LFB-FIOCRUZ 584), serotype H-14 type strain of the Institute Pasteur, Paris. Light and electron microscope observations revealed, by time and endotoxin concentration, increasing damages of the larvae midgut epithelium. The most characteristic effects were midgut columnar cell vacuolization, microvilli damages, epithelium cell contents passing into the midgut lumen and finally the cell death. This article is the first report of the histopathological effects of the Bti endotoxins in the midgut of S. pertinax larvae and the data obtained may contribute to a better understanding of the mode of action of this bacterial strain used as bioinsecticide against black fly larvae.

Histopathological and ultrastructural effects of delta-endotoxins of Bacillus thuringiensis serovar israelensis in the midgut of Simulium pertinax larvae (Diptera, Simuliidae)

The bacterium Bacillus thuringiensis (Bt) produces parasporal crystals containing delta-endotoxins responsible for selective insecticidal activity on larvae. Upon ingestion, these crystals are solubilized in the midgut lumen and converted into active toxins that bind to receptors present on the microvilli causing serious damage to the epithelial columnar cells. We investigated the effect of these endotoxins on larvae of the Simulium pertinax, a common black fly in Brazil, using several concentrations during 4 h of the serovar israelensis strain IPS-82 (LFB-FIOCRUZ 584), serotype H-14 type strain of the Institute Pasteur, Paris. Light and electron microscope observations revealed, by time and endotoxin concentration, increasing damages of the larvae midgut epithelium. The most characteristic effects were midgut columnar cell vacuolization, microvilli damages, epithelium cell contents passing into the midgut lumen and finally the cell death. This article is the first report of the histopathological effects of the Bti endotoxins in the midgut of S. pertinax larvae and the data obtained may contribute to a better understanding of the mode of action of this bacterial strain used as bioinsecticide against black fly larvae.