Public databases of NMR spectra of low molecular weight metabolites must be constructed to remove the major bottleneck of metabolite identification and quantification in the analysis of metabolomics data. Two-dimensional (2-D) 1 H J-resolved spectroscopy represents a popular alternative to 1-D NMR methods, resolving the highly overlapped signals characteristic of complex metabolite mixtures across two frequency dimensions. Here we report the design, measurement and curation of, primarily, a database of 2-D J-resolved NMR spectra.Metabolites were selected based upon their importance within metabolic pathways and their detection potential by NMR, and prepared for analysis at pH 6.6, 7.0 and 7.4. Sixteen NMR spectra were recorded for each metabolite using a 500 MHz spectrometer, including 1-D and 2-D J-resolved spectra, different water suppression methods and different acquisition parameters. Some metabolites were removed due to limited solubility, poor NMR signal quality or contamination, and the final dataset comprised of 3328 NMR spectra arising from 208 metabolite standards. These data are housed in a purpose-built MySQL database (Birmingham Metabolite Library; BML-NMR) containing over 100 separate tables and allowing the efficient storage of raw free-induction-decays (FIDs), 1-D and 2-D NMR spectra and associated metadata. The database is compliant with the Metabolomics Standards Initiative (MSI) endorsed reporting requirements, with some necessary amendments. Library data can be accessed freely and searched through a custom written web interface (www.bml-nmr.org). FIDs, NMR spectra and associated metadata can be downloaded according to a newly implemented MSI-compatible XML schema.

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Clostridium difficile infection is almost unrecognized in mainland China. We have undertaken a study in a large Chinese teaching hospital in Changsha, Hunan, China, to identify cases of C. difficile, record patient characteristics, and define the molecular epidemiology with respect to ribotype distribution and cross-infection. Between April 2009 and February 2010, we examined fecal samples from 70 hospitalized patients with diarrhea who were receiving or had received antibiotics within the previous 6 weeks. Clinical information was collected and the samples were cultured for C. difficile retrospectively. Isolates were ribotyped, and multiple-locus variable-number tandem-repeat assay (MLVA) subtyping was performed on clusters of the same ribotype. The mean age of patients from whom C. difficile was cultured was 58 years, with only 4/21 patients aged >65 years. All patients, with a single exception, had received a third-generation cephalosporin and/or a quinolone antibiotic. Twenty-one isolates of C. difficile were recovered, and seven different ribotypes were identified, the dominant types being 017 (48%), 046 (14%), and 012 (14%). We identified two clusters of cross-infection with indistinguishable isolates of ribotype 017, with evidence of spread both within and between wards. We have identified C. difficile as a possibly significant problem, with cross-infection and a distinct ribotype distribution, in a large Chinese hospital. C. difficile may be underrecognized in China, and further epidemiological studies across the country together with the introduction of routine diagnostic testing are needed to ascertain the size of this potentially significant problem.

Glutaraldehyde-resistant Mycobacterium chelonae have been isolated from endoscope washer disinfectors and endoscope rinse water. The mechanism of glutaraldehyde resistance is not well understood. Two spontaneous, glutaraldehyde-resistant mutants of the sensitive type strain, NCTC 946, were investigated. The colony morphology of the two mutants differed from that of the the type strain: colonies of the former were dry and waxy whereas those of the latter were smooth and shiny. Increased resistance to glutaraldehyde of the mutants was matched by small increases in the MICs of rifampicin and ethambutol but not isoniazid. Both mutants showed increased surface hydrophobicity. No changes were identified in the extractable fatty acids or the mycolic acid components of the cell wall but a reduction in each of the resistant strains in the arabinogalactan/arabinomannan portion of the cell wall was detected.