Fourier transform infrared spectroscopy as a new tool for characterization of mollicutes

Fourier transform infrared (FT-IR) spectroscopy is a convenient physico-chemical technique to investigate various cell materials. Bacteria of class Mollicutes, identified by conventional methods, as Mycoplasma, Acholeplasma and Ureaplasma genera were characterized using this method. A data set of 74 independent experiments corresponding to fourteen reference strains of Mollicutes was examined by FT-IR spectroscopy to attempt a spectral characterization based on the biomolecular structures. In addition to the separation of Mollicutes within the lipidic region into five main clusters corresponding to the three phylogenetic groups tested, FT-IR spectroscopy allowed a fine discrimination between strains belonging to the same species by using selective spectral windows, particularly in the 1200-900 cm(-1) saccharide range. The results obtained by FT-IR were in good agreement with both taxonomic and phylogenetic classifications of tested strains. Thus, this technique appears to be a useful tool and an accurate mean for a rapid characterization of Mollicutes observed in humans.     

Extracellular AGR2 triggers lung tumour cell proliferation through repression of p21CIP1

The human Anterior GRadient 2 (AGR2) protein is an Endoplasmic Reticulum (ER)-resident protein which belongs to the Protein-Disulfide Isomerase (PDI) superfamily and is involved to productive protein folding in the ER. As such AGR2, often found overexpressed in adenocarcinomas, contributes to tumour development by enhancing ER proteostasis. We previously demonstrated that AGR2 is secreted (extracellular AGR2 (eAGR2)) in the tumour microenvironment and plays extracellular roles independent of its ER functions. Herein, we show that eAGR2 triggers cell proliferation and characterize the underlying molecular mechanisms. We demonstrate that eAGR2 enhances tumour cell growth by repressing the tumour suppressor p21^CIP1. Our findings shed light on a novel mechanism through which eAGR2 behaves as a growth factor in the tumour microenvironment, independently of its ER function, thus promoting tumour cell growth through repression of p21^CIP1. Our results provide a rationale for targeting eAGR2/p21^CIP1-based signalling as a potential therapeutic target to impede tumour growth.     

MLVA subtyping of genovar E Chlamydia trachomatis individualizes the Swedish variant and anorectal isolates from men who have sex with men

This study describes a new multilocus variable number tandem-repeat (VNTR) analysis (MLVA) typing system for the discrimination of Chlamydia trachomatis genovar D to K isolates or specimens. We focused our MLVA scheme on genovar E which predominates in most populations worldwide. This system does not require culture and therefore can be performed directly on DNA extracted from positive clinical specimens. Our method was based on GeneScan analysis of five VNTR loci labelled with fluorescent dyes by multiplex PCR and capillary electrophoresis. This MLVA, called MLVA-5, was applied to a collection of 220 genovar E and 94 non-E genovar C. trachomatis isolates and specimens obtained from 251 patients and resulted in 38 MLVA-5 types. The genetic stability of the MLVA-5 scheme was assessed for results obtained both in vitro by serial passage culturing and in vivo using concomitant and sequential isolates and specimens. All anorectal genovar E isolates from men who have sex with men exhibited the same MLVA-5 type, suggesting clonal spread. In the same way, we confirmed the clonal origin of the Swedish new variant of C. trachomatis. The MLVA-5 assay was compared to three other molecular typing methods, ompA gene sequencing, multilocus sequence typing (MLST) and a previous MLVA method called MLVA-3, on 43 genovar E isolates. The discriminatory index was 0.913 for MLVA-5, 0.860 for MLST and 0.622 for MLVA-3. Among all of these genotyping methods, MLVA-5 displayed the highest discriminatory power and does not require a time-consuming sequencing step. The results indicate that MLVA-5 enables high-resolution molecular epidemiological characterisation of C. trachomatis genovars D to K infections directly from specimens.     

The first performance report for the Bio-Rad Dx CT/NG/MG assay for simultaneous detection of Chlamydia trachomatis, Neisseria gonorrhoeae and Mycoplasma genitalium in urogenital samples

We evaluated the clinical performance of the Bio-Rad Dx CT/NG/MG assay for the detection of Chlamydia trachomatis, Mycoplasma genitalium and Neisseria gonorrhoeae in urogenital samples in comparison with the Roche COBAS? TaqMan? CT assay for C. trachomatis and an in-house TaqMan PCR assay for M. genitalium. Swab specimens were cultured for N. gonorrhoeae. In this prospective study, urogenital samples were obtained from symptomatic and asymptomatic patients attending the sexually transmitted disease clinic of Bordeaux, France, from January to April 2010. A total of 658 clinical specimens (259 male and 180 female urines, 191 vaginal, 21 endocervical and 7 urethral swabs) from 453 patients were analyzed. The prevalence of C. trachomatis and M. genitalium infections was 8.1% (21/260) and 1.9% (5/260) in men and 10.4% (20/193) and 2.1% (4/193) in women, respectively. The Bio-Rad Dx CT/NG/MG clinical sensitivity was 100% for C. trachomatis and M. genitalium in men and women. In male urine, the clinical specificity was 99.6% for C. trachomatis and 100% for M. genitalium. In women, the specificity was 99.5% for swabs and 100% for urines for detecting C. trachomatis and M. genitalium. All seven N. gonorrhoeae PCR-positive samples were also positive by culture. Patients were co-infected in 5/57 cases (8.8%), with C. trachomatis and M. genitalium in three cases, and C. trachomatis and N. gonorrhoeae in two cases. In conclusion, the Bio-Rad Dx CT/NG/MG assay can be recommended for the simultaneous detection of C. trachomatis, M. genitalium and N. gonorrhoeae in urogenital specimens of symptomatic and asymptomatic individuals.     

Clostridium difficile electrophoretic typing

Abstract Two typing schemes for Clostridium difficile based on slide agglutinations and polyacrylamide gel electrophoresis (PAGE) have been described. We compared the reference strains of each typing system with a simplified PAGE method using whole cells and Coomassie blue staining. The method was also applied to clinical isolates and immunoblots were performed with a monospecific serum directed against a major band of low molecular weight. The results indicated the great heterogeneity of Clostridium difficile strains complicated by antigenic subdivision for strains belonging to the same electrophoretic type.