In Vivo Characterization of the Activation and Interaction of the VanR-VanS Two-Component Regulatory System Controlling Glycopeptide Antibiotic Resistance in Two Related Streptomyces Species.

This is the author accepted manuscript. The final version is available from the American Society for Microbiology via http://dx.doi.org/10.1128/AAC.01367-15The VanR-VanS two-component system is responsible for inducing resistance to glycopeptide antibiotics in various bacteria. We have performed a comparative study of the VanR-VanS systems from two streptomyces strains, Streptomyces coelicolor and Streptomyces toyocaensis, to characterize how the two proteins cooperate to signal the presence of antibiotics and to define the functional nature of each protein in each strain background. The results indicate that the glycopeptide antibiotic inducer specificity is determined solely by the differences between the amino acid sequences of the VanR-VanS two-component systems present in each strain rather than by any inherent differences in general cell properties, including cell wall structure and biosynthesis. VanR of S. coelicolor (VanRsc) functioned with either sensor kinase partner, while VanR of S. toyocaensis (VanRst) functioned only with its cognate partner, S. toyocaensis VanS (VanSst). In contrast to VanRsc, which is known to be capable of phosphorylation by acetylphosphate, VanRst could not be activated in vivo independently of a VanS sensor kinase. A series of amino acid sequence modifications changing residues in the N-terminal receiver (REC) domain of VanRst to the corresponding residues present in VanRsc failed to create a protein capable of being activated by VanS of S. coelicolor (VanSsc), which suggests that interaction of the response regulator with its cognate sensor kinase may require a region more extended than the REC domain. A T69S amino acid substitution in the REC domain of VanRst produced a strain exhibiting weak constitutive resistance, indicating that this particular amino acid may play a key role for VanS-independent phosphorylation in the response regulator protein.This work was supported by funding from the Medical Research Council, UK (G0700141) and the Royal Society, UK (516002.K5877/ROG). the American Society for Microbiology

Genome-wide dynamics of a bacterial response to antibiotics that target the cell envelope.

BACKGROUND: A decline in the discovery of new antibacterial drugs, coupled with a persistent rise in the occurrence of drug-resistant bacteria, has highlighted antibiotics as a diminishing resource. The future development of new drugs with novel antibacterial activities requires a detailed understanding of adaptive responses to existing compounds. This study uses Streptomyces coelicolor A3(2) as a model system to determine the genome-wide transcriptional response following exposure to three antibiotics (vancomycin, moenomycin A and bacitracin) that target distinct stages of cell wall biosynthesis. RESULTS: A generalised response to all three antibiotics was identified which involves activation of transcription of the cell envelope stress sigma factor σ(E), together with elements of the stringent response, and of the heat, osmotic and oxidative stress regulons. Attenuation of this system by deletion of genes encoding the osmotic stress sigma factor σ(B) or the ppGpp synthetase RelA reduced resistance to both vancomycin and bacitracin. Many antibiotic-specific transcriptional changes were identified, representing cellular processes potentially important for tolerance to each antibiotic. Sensitivity studies using mutants constructed on the basis of the transcriptome profiling confirmed a role for several such genes in antibiotic resistance, validating the usefulness of the approach. CONCLUSIONS: Antibiotic inhibition of bacterial cell wall biosynthesis induces both common and compound-specific transcriptional responses. Both can be exploited to increase antibiotic susceptibility. Regulatory networks known to govern responses to environmental and nutritional stresses are also at the core of the common antibiotic response, and likely help cells survive until any specific resistance mechanisms are fully functional.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Prevalence of Resistance Mechanisms against Macrolides and Lincosamides in Methicillin-Resistant Coagulase-Negative Staphylococci in the Czech Republic and Occurrence of an Undefined Mechanism of Resistance to Lincosamides

High occurrence of the non-macrolide-lincosamide-streptogramin B resistance genes msrA (53%) and linA/linA′ (30%) was found among 98 methicillin-resistant coagulase-negative staphylococci additionally resistant to macrolides and/or lincosamides. The gene msrA predominated in Staphylococcus haemolyticus (43 of 62 isolates). In Staphylococcus epidermidis, it was present in 7 of 27 isolates. A novel mechanism of resistance to lincosamides appears to be present in 10 genetically related isolates of S. haemolyticus in the absence of ermA, ermC, msrA, and linA/linA′

Peer and sibling substance use: predictors of substance use among adolescents in Mexico El uso de sustancias por pares y hermanos como factor pronóstico del uso de sustancias por adolescentes en México

OBJECTIVE: To examine the extent to which peer drug use and sibling drug use predict alcohol abuse/dependence disorder status and the use of drugs other than alcohol among school-based youth in Mexico. METHODS: Data were collected on 1 203 middle and high school students in northern Mexico in May 1998. Participation was voluntary, and responses were confidential. Logistic regression analyses estimated the association that peer drug use and that sibling drug use had with alcohol abuse/dependence diagnosis and the lifetime use of drugs other than alcohol. RESULTS: Students who had siblings or peers who used alcohol and other drugs were more likely to meet the standard alcohol abuse/dependence criteria defined by the Diagnostic and Statistical Manual of Mental Disorders Fourth Edition (DSM-IV), and were more likely to have used drugs other than alcohol. Controlling for potentially important confounders, we found that adolescents with the highest level of peer substance use were eight times as likely to meet alcohol abuse/dependence criteria and four times as likely to use other drugs. Youth who had siblings who used drugs were about twice as likely to meet alcohol abuse/dependence criteria and about 2.5 times as likely to use drugs other than alcohol when compared to youth with no sibling substance use. CONCLUSIONS: Consistent with extant findings among youth in the United States of America, peer and sibling substance use are major risk factors for substance use among school-based youth in Mexico. Students in Mexico may benefit from prevention strategies found to be effective among students in the United States.OBJECTIVO: Examinar en qué medida el uso de drogas por los pares y hermanos es factor pronóstico del abuso o la dependencia del alcohol y del uso de drogas distintas del alcohol en escolares mexicanos. MÉTODOS: Se recolectaron datos acerca de 1 203 estudiantes de los últimos años de primaria y de secundaria en el norte de México en mayo de 1998. La participación en el estudio fue voluntaria, y las respuestas fueron confidenciales. Mediante análisis de regresión logística se estimó la asociación entre el uso de drogas por los pares y hermanos por un lado, y por el otro el diagnóstico de abuso o dependencia del alcohol y el uso de sustancias distintas del alcohol en algún momento de la vida. RESULTADOS: Los estudiantes cuyos hermanos o pares ingerían bebidas alcohólicas y consumían otras drogas mostraron mayores probabilidades de satisfacer los criterios estándares de abuso o dependencia del alcohol, según los define el Manual diagnóstico y estadístico de enfermedades mentales, cuarta edición (MDE-IV), y de haber consumido drogas distintas del alcohol. Después de controlado el efecto de posibles factores de confusión, los adolescentes con los niveles más altos de abuso de sustancias por parte de sus pares se mostraron ocho veces más propensos a satisfacer los criterios de abuso o dependencia del alcohol y cuatro veces más propensos a consumir otros tipos de sustancias. Los adolescentes cuyos hermanos consumían drogas tenían una probabilidad dos veces mayor de satisfacer los criterios de abuso o dependencia del alcohol y una probabilidad 2,5 veces mayor de consumir drogas en comparación con jóvenes cuyos hermanos no consumían ninguna sustancia. CONCLUSIONES: Tal como indican otros resultados obtenidos con adolescentes en Estados Unidos de América, el uso de sustancias por los pares y hermanos es un factor de riesgo de consumo de sustancias en escolares en México. Estos últimos podrían beneficiarse de estrategias preventivas cuya eficacia en jóvenes estadounidenses se haya demostrado

Two Novel Semisynthetic Lipoglycopeptides Active against Staphylococcus aureus Biofilms and Cells in Late Stationary Growth Phase

The increase in antibiotic resistance among Gram-positive bacteria underscores the urgent need to develop new antibiotics. New antibiotics should target actively growing susceptible bacteria that are resistant to clinically accepted antibiotics including bacteria that are not growing or are protected in a biofilm environment. In this paper, we compare the in vitro activities of two new semisynthetic glycopeptide antibiotics, MA79 and ERJ390, with two clinically used glycopeptide antibiotics—vancomycin and teicoplanin. The new antibiotics effectively killed not only exponentially growing cells of Staphylococcus aureus, but also cells in the stationary growth phase and biofilm