Yersinia pestis Orientalis in Remains of Ancient Plague Patients

Yersinia pestis DNA was recently detected in human remains from 2 ancient plague pandemics in France and Germany. We have now sequenced Y. pestis glpD gene in such remains, showing a 93-bp deletion specific for biotype Orientalis. These data show that only Orientalis type caused the 3 plague pandemics

Soft topographic map for clustering and classification of bacteria

In this work a new method for clustering and building a topographic representation of a bacteria taxonomy is presented. The method is based on the analysis of stable parts of the genome, the so-called “housekeeping genes”. The proposed method generates topographic maps of the bacteria taxonomy, where relations among different type strains can be visually inspected and verified. Two well known DNA alignement algorithms are applied to the genomic sequences. Topographic maps are optimized to represent the similarity among the sequences according to their evolutionary distances. The experimental analysis is carried out on 147 type strains of the Gammaprotebacteria class by means of the 16S rRNA housekeeping gene. Complete sequences of the gene have been retrieved from the NCBI public database. In the experimental tests the maps show clusters of homologous type strains and present some singular cases potentially due to incorrect classification or erroneous annotations in the database

NMNI editorial report, 2016

International audienc

Surviving within the amoebal exocyst: the Mycobacterium avium complex paradigm

<p>Abstract</p> <p>Background</p> <p>Most of environmental mycobacteria have been previously demonstrated to resist free-living amoeba with subsequent increased virulence and resistance to antibiotics and biocides. The <it>Mycobacterium avium </it>complex (MAC) comprises of environmental organisms that inhabit a wide variety of ecological niches and exhibit a significant degree of genetic variability. We herein studied the intra-ameobal location of all members of the MAC as model organisms for environmental mycobacteria.</p> <p>Results</p> <p>Type strains for <it>M. avium</it>, <it>Mycobacterium intracellulare</it>, <it>Mycobacterium chimaera</it>, <it>Mycobacterium colombiense</it>, <it>Mycobacterium arosiense</it>, <it>Mycobacterium marseillense</it>, <it>Mycobacterium timonense </it>and <it>Mycobacterium bouchedurhonense </it>were co-cultivated with the free-living amoeba <it>Acanthamoeba polyphaga </it>strain Linc-AP1. Microscopic analyses demonstrated the engulfment and replication of mycobacteria into vacuoles of <it>A. polyphaga </it>trophozoites. Mycobacteria were further entrapped within amoebal cysts, and survived encystment as demonstrated by subculturing. Electron microscopy observations show that, three days after entrapment into <it>A. polyphaga </it>cysts, all MAC members typically resided within the exocyst.</p> <p>Conclusions</p> <p>Combined with published data, these observations indicate that mycobacteria are unique among amoeba-resistant bacteria, in residing within the exocyst.</p

Rapid detection of laboratory cross-contamination with Mycobacterium tuberculosis using multispacer sequence typing

<p>Abstract</p> <p>Background</p> <p>The ability to culture <it>Mycobacterium tuberculosis </it>from clinical specimens serves as the gold standard for the diagnosis of tuberculosis. However, a number of false-positive diagnoses may be due to cross-contamination of such specimens. We herein investigate such episode of cross-contamination by using a technique known as multispacer sequence typing (MST). This technique was applied to six <it>M. tuberculosis </it>isolates prepared within the same laboratory over a two-week period of time.</p> <p>Results</p> <p>MST analysis indicated a unique and common sequence profile between a strain isolated from a patient with proven pulmonary tuberculosis and a strain isolated from a patient diagnosed with lung carcinoma. Using this approach, we were able to provide a clear demonstration of laboratory cross-contamination within just four working days. Further epidemiological investigations revealed that the two isolates were processed for culture on the same day.</p> <p>Conclusion</p> <p>The application of MST has been demonstrated to serve as a rapid and efficient method to investigate cases of possible cross-contamination with <it>M. tuberculosis</it>.</p

Bartonella quintana in Domestic Cat

We recovered Bartonella quintana DNA from dental pulp of a domestic cat. This study, the first to detect B. quintana in a nonhuman mammal, changes our understanding of the epidemiology of this infection and proposes that cats may be an emerging source of human infection

Acanthamoeba polyphaga-Enhanced Growth of Mycobacterium smegmatis

Background: Mycobacterium smegmatis is a rapidly-growing mycobacterium causing rare opportunistic infections in human patients. It is present in soil and water environments where free-living amoeba also reside, but data regarding M. smegmatis-amoeba relationships have been contradictory from mycobacteria destruction to mycobacteria survival. Methodology/Principal Findings: Using optic and electron microscopy and culture-based microbial enumeration we investigated the ability of M. smegmatis mc 2 155, M. smegmatis ATCC 19420 T and M. smegmatis ATCC 27204 organisms to survive into Acanthamoeba polyphaga trophozoites and cysts. We observed that M. smegmatis mycobacteria penetrated and survived in A. polyphaga trophozoites over five-day co-culture resulting in amoeba lysis and the release of viable M. smegmatis mycobacteria without amoebal cyst formation. We further observed that amoeba-co-culture, and lysed amoeba and supernatant and pellet, significantly increased five-day growth of the three tested M. smegmatis strains, including a four-fold increase in intra-amoebal growth. Conclusions/Significance: Amoebal co-culture increases the growth of M. smegmatis resulting in amoeba killing by replicating M. smegmatis mycobacteria. This amoeba-M. smegmatis co-culture system illustrates an unusual paradigm in the mycobacteria-amoeba interactions as mycobacteria have been mainly regarded as amoeba-resistant organisms. Using these model organisms, this co-culture system could be used as a simple and rapid model to probe mycobacterial factors implicated in the intracellular growth of mycobacteria