Early Detection of Bacillus anthracis From Saliva in Anticipation of a Bioterrorism Attack

Objective: To assess potential for early detection of oral infection by B. anthracis spores for preparedness of a bioterrorism attack. Material and Methods: The laboratory study used saliva with a range of initial anthrax concentrations, to compare detection by direct observation from conventional blood agar culture and by anthrax-specific PCR after a shorter culture in BHI broth. Three types of saliva were collected: stimulated saliva, unstimulated/whole saliva, and unstimulated/whole saliva with antibiotic treatment (for negative control). Using bivariate Kruskal-Wallis and Mann-Whitney tests for statistical analysis for factors that could affecting anthrax detection, significant differences between the test groups was assumed at p<0.05. Results: From unstimulated whole saliva heat shock treated at 62.50C, B. anthracis growth was detected with both methods. PCR detection from a BHI broth culture could shorten the time to diagnosis in comparison to conventional culture in blood agar. Conclusion: Saliva can provide useful samples for diagnosis of oropharyngeal anthrax. In comparison to conventional culture on blood agar, shorter-term culture in BHI broth provides potential for earlier detection and diagnosis.

Ántrax cutáneo, último brote diagnosticado en Chile / Cutaneous anthrax, the last outbreak diagnosed in Chile

Resumen El ántrax, es una zoonosis causada por una bacteria generadora de esporas, llamada Bacillus anthracis. En forma natural tiene una distribución global, con una predilección en zonas agrícolas con pocas normativas de sanidad pública veterinaria. El contagio humano ocurre por el consumo de carnes de animales enfermos, por contacto a través de una puerta de entrada en la piel o por la inhalación de esporas de productos derivados del animal afectado (lana, cuero, huesos). La infección en los seres humanos compromete con mayor frecuencia la piel, seguido por el tracto gastrointestinal y los pulmones. El control de la enfermedad se basa en la prevención, de allí la importancia de la vigilancia en la detección de casos y brotes. Presentamos el último brote de ántrax cutáneo diagnosticado en Chile con descripción de dos primeros casos clínicos del brote.

Anthrax is a zoonosis caused by a spore-forming bacterium, called Bacillus anthracis. Naturally it is of global distribution, with a predilection in agricultural zones with few norms of public veterinary health. Human contagion occurs through the consumption of diseased animal's meat or through a doorway into the skin or through the spores inhalation of products derived from the affected animal (wool, leather, bones). The most frequent infection in humans occurs in the skin, followed by the gastrointestinal tract and lungs. We present the last outbreak of cutaneous anthrax diagnosed in Chile with a description of the first two clinical cases of the outbreak. Control disease is based on prevention, hence the importance of surveillance in detecting cases and outbreaks.

Bacillus anthracis: una mirada molecular a un patógeno célebre / Bacillus anthracis: a molecular look at a famous pathogen

Bacillus anthracis es un bacilo gram positivo del grupo Bacillus cereus, que posee un genoma extremadamente monomórfco y comparte gran similitud fsiológica y de estructura genética con B. cereus y Bacillus thuringiensis. En este artículo se describen nuevos métodos moleculares para la identifcación y tipifcación de B. anthracis, basados en repeticiones en tándem de número variable o en diferencias genéticas detectadas por secuenciación, desarrollados en los últimos años. Los aspectos moleculares de los factores de virulencia tradicionales, cápsula, antígeno protector, factor letal y factor edema se describen en profundidad, junto con factores de virulencia recientemente propuestos, como los sideróforos, petrobactina y bacilibactina, la adhesina de la capa S y la lipoproteína MntA. También se detalla la organización molecular de los megaplásmidos pXO1 y pXO2, incluyendo la isla de patogenicidad de pXO1. El esqueleto genético de estos plásmidos se ha encontrado en otras especies relacionadas, probablemente debido a eventos de transferencia lateral. Finalmente, se presentan los dos receptores celulares del antígeno protector, ANTXR1/TEM8 y ANTXR2/CMG2, esenciales en la interacción del patógeno con el hospedador. Los estudios moleculares realizados en los últimos años han permitido aumentar enormemente el conocimiento de los diferentes aspectos de este microorganismo y su relación con el hospedador, pero a la vez han abierto nuevos interrogantes sobre este notorio patógeno.

Bacillus anthracis, a gram-positive rod belonging to the Bacillus cereus group, has an extremely monomorphic genome, and presents high structural and physiological similarity with B. cereus and Bacillus thuringiensis. In this work, the new molecular methods for the identifcation and typing of B. anthracis developed in the last years, based on variable number tandem repeats or on genetic differences detected through sequencing, are described. The molecular aspects of traditional virulence factors: capsule, protective antigen, lethal factor and edema factor are described in depth, together with virulence factors recently proposed, such as the siderophores petrobactin and bacillibactin, the S-layer adhesin and the MntA lipoprotein. It is detailed the molecular organization of megaplasmids pXO1 and pXO2, including the pathogenicity island of pXO1. The genetic skeleton of these plasmids has been observed in related species, and this could be attributed to lateral gene transfer. Finally, the two anthrax toxin protective antigen receptors, ANTXR1/TEM8 and ANTXR2/CMG2, essential for the interaction of the pathogen with the host, are presented. The molecular studies performed in recent years have greatly increased knowledge in different aspects of this microorganism and its relationship with the host, but at the same time they have raised new questions about this noted pathogen.