Identification of a locus involved in the utilization of iron by Actinobacillus pleuropneumoniae

The cloned afu locus of Actinobacillus pleuropneumoniae restored the ability of an Escherichia coli K-12 mutant (aroB) to grow on iron-limited media. DNA sequence analysis of the fragment showed that there are three genes designated afuA, afuB and afuC (Actinobacillus ferric uptake) that encode products similar to the SfuABC proteins of Serratia marcescens, the HitABC proteins of Haemophilia influenzae, the FbpABC proteins of Neisseria gonorrhoeae and the YfuABC proteins of Yersinia enterocolitica. The three genes encode a periplasmic iron-binding protein (AfuA), a highly hydrophobic integral cytoplasmic membrane protein with two consensus permease motifs (AfuB) and one hydrophilic peripheral cytoplasmic membrane protein with Walker ATP-binding motifs (AfuC), respectively. This system has been shown to constitute a periplasmic binding protein-dependent iron transport system in these organisms. The afuABC operon is locating approximately 200 bp upstream of apxIC gene, but transcribed in opposite direction to the ApxI-toxin gene

Microbial Diagnostic Array Workstation (MDAW): a web server for diagnostic array data storage, sharing and analysis

<p>Abstract</p> <p>Background</p> <p>Microarrays are becoming a very popular tool for microbial detection and diagnostics. Although these diagnostic arrays are much simpler when compared to the traditional transcriptome arrays, due to the high throughput nature of the arrays, the data analysis requirements still form a bottle neck for the widespread use of these diagnostic arrays. Hence we developed a new online data sharing and analysis environment customised for diagnostic arrays.</p> <p>Methods</p> <p>Microbial Diagnostic Array Workstation (MDAW) is a database driven application designed in MS Access and front end designed in ASP.NET.</p> <p>Conclusion</p> <p>MDAW is a new resource that is customised for the data analysis requirements for microbial diagnostic arrays.</p

Hospitalized Pediatric Parainfluenza Virus Infections in a Medical Center

Background/PurposeParainfluenza viruses (PIVs) are common pathogens in respiratory tract infections. The aims of this study were to determine the clinical presentation of PIV infections in hospitalized children and to identify particular clinical indications that may effectively distinguish between different PIV serotypes.MethodsA retrospective review of data from children hospitalized with PIV infections at the Mackay Memory Hospital in Taipei between January 2005 and December 2007 was undertaken. Symptoms, signs, laboratory findings and seasonal variations between different types of PIV (serotypes 1, 2 and 3) were compared.ResultsA total of 206 patients [119 (57.8%) boys and 87 (42.2%) girls] were enrolled in the study. Seventy-four (35.9%) patients were infected with PIV serotype 1, 25 (12.1%) with serotype 2 and 107 (51.9%) with serotype 3. The most common clinical presentations were fever (81.1%), cough (66.0%), rhinorrhea (44.2%) and hoarseness (22.3%); 4.9% of the infected children also had skin rashes. No significant differences were found in average white blood cell counts and C-reactive protein levels between the three serotypes. PIV serotype 1 infections were discernible throughout the year; serotype 2 tended to cluster in the late summer and autumn of 2005 and 2007; and serotype 3 was more common in the spring and early summer.ConclusionThe clinical presentation of PIV infection in hospitalized children ranges from upper respiratory tract infection to croup, bronchiolitis and viral bronchopneumonia, with the different types of PIV infections giving rise to similar symptoms. The seasonal distribution of the different serotypes is, nevertheless, quite distinct

Analysis of Ultra Low Genome Conservation in Clostridium difficile

Microarray-based comparative genome hybridisations (CGH) and genome sequencing of Clostridium difficile isolates have shown that the genomes of this species are highly variable. To further characterize their genome variation, we employed integration of data from CGH, genome sequencing and putative cellular pathways. Transcontinental strain comparison using CGH data confirmed the emergence of a human-specific hypervirulent cluster. However, there was no correlation between total toxin production and hypervirulent phenotype, indicating the possibility of involvement of additional factors towards hypervirulence. Calculation of C. difficile core and pan genome size using CGH and sequence data estimated that the core genome is composed of 947 to 1,033 genes and a pan genome comprised of 9,640 genes. The reconstruction, annotation and analysis of cellular pathways revealed highly conserved pathways despite large genome variation. However, few pathways such as tetrahydrofolate biosynthesis were found to be variable and could be contributing to adaptation towards virulence such as antibiotic resistance

Real-Time Bioluminescence Imaging of Mixed Mycobacterial Infections

Molecular analysis of infectious processes in bacteria normally involves construction of isogenic mutants that can then be compared to wild type in an animal model. Pathogenesis and antimicrobial studies are complicated by variability between animals and the need to sacrifice individual animals at specific time points. Live animal imaging allows real-time analysis of infections without the need to sacrifice animals, allowing quantitative data to be collected at multiple time points in all organs simultaneously. However, imaging has not previously allowed simultaneous imaging of both mutant and wild type strains of mycobacteria in the same animal. We address this problem by using both firefly (Photinus pyralis) and click beetle (Pyrophorus plagiophthalamus) red luciferases, which emit distinct bioluminescent spectra, allowing simultaneous imaging of two different mycobacterial strains during infection. We also demonstrate that these same bioluminescence reporters can be used to evaluate therapeutic efficacy in real-time, greatly facilitating our ability to screen novel antibiotics as they are developed. Due to the slow growth rate of mycobacteria, novel imaging technologies are a pressing need, since they can they can impact the rate of development of new therapeutics as well as improving our understanding of virulence mechanisms and the evaluation of novel vaccine candidates