Nanobacteria Are Mineralo Fetuin Complexes

“Nanobacteria” are nanometer-scale spherical and ovoid particles which have spurred one of the biggest controversies in modern microbiology. Their biological nature has been severely challenged by both geologists and microbiologists, with opinions ranging from considering them crystal structures to new life forms. Although the nature of these autonomously replicating particles is still under debate, their role in several calcification-related diseases has been reported. In order to gain better insights on this calciferous agent, we performed a large-scale project, including the analysis of “nanobacteria” susceptibility to physical and chemical compounds as well as the comprehensive nucleotide, biochemical, proteomic, and antigenic analysis of these particles. Our results definitively ruled out the existence of “nanobacteria” as living organisms and pointed out the paradoxical role of fetuin (an anti-mineralization protein) in the formation of these self-propagating mineral complexes which we propose to call “nanons.” The presence of fetuin within renal calculi was also evidenced, suggesting its role as a hydroxyapatite nucleating factor

Lovastatin Protects against Experimental Plague in Mice

Background: Plague is an ectoparasite-borne deadly infection caused by Yersinia pestis, a bacterium classified among the group A bioterrorism agents. Thousands of deaths are reported every year in some African countries. Tetracyclines and cotrimoxazole are used in the secondary prophylaxis of plague in the case of potential exposure to Y. pestis, but cotrimoxazole-resistant isolates have been reported. There is a need for additional prophylactic measures. We aimed to study the effectiveness of lovastatin, a cholesterol-lowering drug known to alleviate the symptoms of sepsis, for plague prophylaxis in an experimental model. Methodology: Lovastatin dissolved in Endolipide was intraperitoneally administered to mice (20 mg/kg) every day for 6 days prior to a Y. pestis Orientalis biotype challenge. Non-challenged, lovastatin-treated and challenged, untreated mice were also used as control groups in the study. Body weight, physical behavior and death were recorded both prior to infection and for 10 days post-infection. Samples of the blood, lungs and spleen were collected from dead mice for direct microbiological examination, histopathology and culture. The potential antibiotic effect of lovastatin was tested on blood agar plates. Conclusions/Significance: Lovastatin had no in-vitro antibiotic effect against Y. pestis. The difference in the mortality between control mice (11/15; 73.5%) and lovastatin-treated mice (3/15; 20%) was significant (P,0.004; Mantel-Haensze

Microarray for serotyping of <it>Bartonella </it>species

Abstract Background Bacteria of the genus Bartonella are responsible for a large variety of human and animal diseases. Serological typing of Bartonella is a method that can be used for differentiation and identification of Bartonella subspecies. Results We have developed a novel multiple antigenic microarray to serotype Bartonella strains and to select poly and monoclonal antibodies. It was validated using mouse polyclonal antibodies against 29 Bartonella strains. We then tested the microarray for serotyping of Bartonella strains and defining the profile of monoclonal antibodies. Bartonella strains gave a strong positive signal and all were correctly identified. Screening of monoclonal antibodies towards the Gro EL protein of B. clarridgeiae identified 3 groups of antibodies, which were observed with variable affinities against Bartonella strains. Conclusion We demonstrated that microarray of spotted bacteria can be a practical tool for serotyping of unidentified strains or species (and also for affinity determination) by polyclonal and monoclonal antibodies. This could be used in research and for identification of bacterial strains.</p

Experimental Survival of Mycobacterium ulcerans in Watery Soil, a Potential Source of Buruli Ulcer

International audienceThe reservoir of Mycobacterium ulcerans causing Buruli ulcer (BU) remains unknown. Here, sterilized watery soil was mixed with 2 x 10(6) colony-forming units (CFU)/g of M. ulcerans Agy99 or M. ulcerans ATCC 33728 and incubated in a microaerophilic atmosphere in the presence of negative controls. Both M ulcerans strains survived in soil for 4 months with a final inoculum of 300 110 CFU/g. Further, three groups of five mice with and without footpad scarification were exposed to control soil or M u/cerans-inoculated soil. Although no specific clinical and histopathological lesions were observed in control animals, red spots observed on 8/20 scarified feet in 8/10 challenged mice yielded inflammatory infiltrates and positive real-time polymerase chain reaction detection of M. ulcerans DNA in five mice. BU can be acquired as an inoculation infection with watery soil as a transient source of infection. These experimental observations warrant additional field observations

Characterization of rickettsial adhesin Adr2 belonging to a new group of adhesins in α-proteobacteria

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Mouse Model of Coxiella burnetii Aerosolization

International audienceCoxiella burnetii is mainly transmitted by aerosols and is responsible ă for multiple-organ lesions. Animal models have shown C. burnetii ă pathogenicity, but long-term outcomes still need to be clarified. We ă used a whole-body aerosol inhalation exposure system to mimic the ă natural route of infection in immunocompetent (BALB/c) and severe ă combined immunodeficient (SCID) mice. After an initial lung inoculum of ă 10(4) C. burnetii cells/lung, the outcome, serological response, ă hematological disorders, and deep organ lesions were described up to 3 ă months postinfection. C. burnetii-specific PCR, anti-C. burnetii ă immunohistochemistry, and fluorescent in situ hybridization (FISH) ă targeting C. burnetii-specific 16S rRNA completed the detection of the ă bacterium in the tissues. In BALB/c mice, a thrombocytopenia and ă lymphopenia were first observed, prior to evidence of C. burnetii ă replication. In all SCID mouse organs, DNA copies increased to higher ă levels over time than in BALB/c ones. Clinical signs of discomfort ă appeared in SCID mice, so follow-up had to be shortened to 2 months in ă this group. At this stage, all animals presented bone, cervical, and ă heart lesions. The presence of C. burnetii could be attested in situ for ă all organs sampled using immunohistochemistry and FISH. This mouse model ă described C. burnetii Nine Mile strain spread using aerosolization in a ă way that corroborates the pathogenicity of Q fever described in humans ă and completes previously published data in mouse models. C. burnetii ă infection occurring after aerosolization in mice thus seems to be a ă useful tool to compare the pathogenicity of different strains of C. ă burnetii

HES staining of lung tissue (a; original magnification, 100×) and spleen tissue (b; original magnification ×50) from group B mice after lovastatin prophylaxis and <i>Y. pestis</i> challenge.

<p>No pathological changes were observed; particularly, no inflammatory infiltrates or necrotic areas were detected.</p