Phenotypic characterization of Clostridium botulinum strains isolated from infant botulism cases in Argentina

Infant botulism is the most common form of human botulism; however, its transmission has not been completely explained yet. Some of the most recognized potential sources of Clostridium botulinum spores are the soil, dust, honey and medicinal herbs. In Argentina, 456 cases of infant botulism were reported between 1982 and 2007. C. botulinum type A was identified in 455 of these cases whereas type B was identified in just one case. However, in Argentina, types A, B, E, F, G, and Af have been isolated from environmental sources. It is not clearly known if strains isolated from infant botulism cases have different characteristics from strains isolated from other sources. During this study, 46 C. botulinum strains isolated from infant botulism cases and from environmental sources were typified according to phenotypic characteristics. Biochemical tests, antimicrobial activity, and haemagglutinin-negative botulinum neurotoxin production showed uniformity among all these strains. Despite the variability observed in the botulinum neurotoxin's binding to cellular receptors, no correlation was found between these patterns and the source of the botulinum neurotoxin. However, an apparent geographical clustering was observed, since strains isolated from Argentina had similar characteristics to those isolated from Italy and Japan, but different to those isolated from the United States.Fil: Sagua, Maria Delia. Universidad Nacional de Cuyo; ArgentinaFil: Lúquez, Carolina. Universidad Nacional de Cuyo; ArgentinaFil: Bianco, María Isabel. Universidad Nacional de Cuyo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Fernandez, Rafael Alfredo. Universidad Nacional de Cuyo; Argentin

Sequence Diversity of Genes Encoding Botulinum Neurotoxin Type F ▿ †

Botulism due to type F botulinum neurotoxin (BoNT/F) is rare (<1% of cases), and only a limited number of clostridial strains producing this toxin type have been isolated. As a result, analysis of the diversity of genes encoding BoNT/F has been challenging. In this study, the entire bont/F nucleotide sequences were determined from 33 type F botulinum toxin-producing clostridial strains isolated from environmental sources and botulism outbreak investigations. We examined proteolytic and nonproteolytic Clostridium botulinum type F strains, bivalent strains, including Bf and Af, and Clostridium baratii type F strains. Phylogenetic analysis revealed that the bont/F genes examined formed 7 subtypes (F1 to F7) and that the nucleotide sequence identities of these subtypes differed by up to 25%. The genes from proteolytic (group I) C. botulinum strains formed subtypes F1 through F5, while the genes from nonproteolytic (group II) C. botulinum strains formed subtype F6. Subtype F7 was composed exclusively of bont/F genes from C. baratii strains. The region of the bont/F5 gene encoding the neurotoxin light chain was found to be highly divergent compared to the other subtypes. Although the bont/F5 nucleotide sequences were found to be identical in strains harboring this gene, the gene located directly upstream (ntnh/F) demonstrated sequence variation among representative strains of this subtype. These results demonstrate that extensive nucleotide diversity exists among genes encoding type F neurotoxins from strains with different phylogenetic backgrounds and from various geographical sources

First Report Worldwide of an Infant Botulism Case Due to Clostridium botulinum Type E▿

Clostridium botulinum type E has been associated with botulism in adults but never in infants. Infant botulism type E cases have been associated with neurotoxigenic strains of C. butyricum. We report the first infant botulism case due to C. botulinum type E worldwide

Distribution of Botulinum Toxin-Producing Clostridia in Soils of Argentina

We studied the presence of botulinum toxin-producing clostridia in 2,009 soil samples from five geographical regions of Argentina. The prevalence was 23.5%, and the distribution was not homogeneous among the regions. We observed a great multiplicity of serological types and a higher prevalence in nonvirgin soils than in virgin soils

Asymmetric Type F Botulism with Cranial Nerve Demyelination

We report a case of type F botulism in a patient with bilateral but asymmetric neurologic deficits. Cranial nerve demyelination was found during autopsy. Bilateral, asymmetric clinical signs, although rare, do not rule out botulism. Demyelination of cranial nerves might be underrecognized during autopsy of botulism patients