Drug and Alcohol Rehabilitation: Sub-Inhibitory Cefsulodin Sensitization of E. Coli to ?-Lactams Is Mediated by PBP1b Inhibition.
Sub-Inhibitory Cefsulodin Sensitization of E. coli to ?-lactams Is Mediated by PBP1b Inhibition.
Filed under: Drug and Alcohol Rehabilitation
PLoS One. 2012; 7(11): e48598
Sarkar SK, Dutta M, Kumar A, Mallik D, Ghosh AS
The combination of antibiotics is one of the strategies to combat drug-resistant bacteria, though only a handful of such combinations are in use, such as the ?-lactam combinations. In the present study, the efficacy of a specific sub-inhibitory concentration of cefsulodin with other ?-lactams was evaluated against a range of Gram-negative clinical isolates. This approach increased the sensitivity of the isolates, regardless of the ?-lactamase production. The preferred target and mechanism of action of cefsulodin were identified in laboratory strains of Escherichia coli, by examining the effects of deleting the penicillin-binding protein (PBP) 1a and 1b encoding genes individually. Deletion of PBP1b was involved in sensitizing the bacteria to ?-lactam agents, irrespective of its O-antigen status. Moreover, the use of a sub-inhibitory concentration of cefsulodin in combination with a ?-lactam exerted an effect similar to that one obtained for PBP1b gene deletion. We conclude that the identified ?-lactam/cefsulodin combination works by inhibiting PBP1b (at least partially) despite the involvement of ?-lactamases, and therefore could be extended to a broad range of Gram-negative pathogens.
HubMed – drug
Detection of Bacterial 16S rRNA and Identification of Four Clinically Important Bacteria by Real-Time PCR.
Filed under: Drug and Alcohol Rehabilitation
PLoS One. 2012; 7(11): e48558
Clifford RJ, Milillo M, Prestwood J, Quintero R, Zurawski DV, Kwak YI, Waterman PE, Lesho EP, Mc Gann P
Within the paradigm of clinical infectious disease research, Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa represent the four most clinically relevant, and hence most extensively studied bacteria. Current culture-based methods for identifying these organisms are slow and cumbersome, and there is increasing need for more rapid and accurate molecular detection methods. Using bioinformatic tools, 962,279 bacterial 16S rRNA gene sequences were aligned, and regions of homology were selected to generate a set of real-time PCR primers that target 93.6% of all bacterial 16S rRNA sequences published to date. A set of four species-specific real-time PCR primer pairs were also designed, capable of detecting less than 100 genome copies of A. baumannii, E. coli, K. pneumoniae, and P. aeruginosa. All primers were tested for specificity in vitro against 50 species of Gram-positive and -negative bacteria. Additionally, the species-specific primers were tested against a panel of 200 clinical isolates of each species, randomly selected from a large repository of clinical isolates from diverse areas and sources. A comparison of culture and real-time PCR demonstrated 100% concordance. The primers were incorporated into a rapid assay capable of positive identification from plate or broth cultures in less than 90 minutes. Furthermore, our data demonstrate that current targets, such as the uidA gene in E.coli, are not suitable as species-specific genes due to sequence variation. The assay described herein is rapid, cost-effective and accurate, and can be easily incorporated into any research laboratory capable of real-time PCR.
HubMed – drug
Comparison on Virulence and Immunogenicity of Two Recombinant Vaccinia Vaccines, Tian Tan and Guang9 Strains, Expressing the HIV-1 Envelope Gene.
Filed under: Drug and Alcohol Rehabilitation
PLoS One. 2012; 7(11): e48343
Zhu R, Huang W, Wang W, Liu Q, Nie J, Meng S, Yu Y, Wang Y
The vaccinia virus Guang9 strain (VG9), derived from the vaccinia virus Tian Tan strain (VTT) has been found to be less virulent than VTT.To investigate whether VG9 could be a potential replicating virus vector, the TK genes in VG9 and VTT were replaced with the HIV-1 envelope gene via homologous recombination, resulting in the recombinant viruses, VG9-E and VTT-E. The biology, virulence, humoral and cellular immunological responses of VG9-E and VTT-E were evaluated. Our results indicated no obvious difference in range of host cells and diffusion between two recombinant viruses. Neurovirulence for VG9-E in weanling and suckling mice, and skin virulence in rabbits, were lower than that of VTT-E. The humoral immune responses, including binding antibody and neutralizing antibody responses, induced by VG9-E were not significantly different from those for VTT-E whilst IFN-? response which represented cellular immune response induced by VG9-E was significantly higher than that did by VTT-E.Our results indicated that VG9-E was less virulent, yet induced higher cellular immune response than VTT-E. Therefore, it could be an ideal replicating vaccinia vector for HIV vaccine research and development.
HubMed – drug
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