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Objectives Amphotericin B (AmB) is a drug of choice for treatment of disseminated fungal infections, but its use is often associated with severe adverse effects. Our observation that generic formulations of AmB contain multiple polyene components led us to propose that removal of other polyenes would yield a high purity AmB (AmBHP) with an improved therapeutic index. Methods To test that premise, AmBHP was first isolated from generic AmB by semi-preparative reverse phase high-pressure liquid chromatography and then its effects were compared in vitro and in vivo with those of commercial AmB formulations. Results AmBHP proved to be as active as generic AmB against Candida albicans in vitro and as efficacious as both generic and lipid-complexed AmB in a Candida-infected mouse model. AmBHP appeared to be less toxic to human THP-1 monocytic cells than was generic AmB at low concentrations (in vivo, as indicated by its apparent LD50 and survival of Candida-infected mice, was roughly twofold less than that to generic or lipid-complexed AmB. Likewise, AmBHP decreased mean glomerular filtration rate about half as much as did a 10-fold lower dose of PTAmB. Conclusions Taken together, these data indicate that AmBHP may represent a refinement of currently marketed AmB formulations, offering equal, if not better, efficacy with less toxicity. [ABSTRACT FROM AUTHOR]

Objectives The aim of this study was to identify changes in the gene expression profile of Streptococcus pneumoniae in response to a subinhibitory concentration of penicillin in an effort to better understand mechanisms by which this organism copes with this stress. Methods S. pneumoniae serotype 2 strain D39 was grown for 1 h in the presence or absence of penicillin at a concentration equivalent to half the MIC (0.03 mg/L). RNA was isolated and gene expression profiles were compared using DNA microarrays. Differential expression of select genes was confirmed by real-time RT–PCR. Results A total of 386 genes were found to be responsive to penicillin. Up-regulated genes included those of the ciaR–ciaH operon, luxS, genes encoding cell envelope proteins and genes of the pst locus. Down-regulated genes included genes involved in competence, genes encoding capsular polysaccharide biosynthesis proteins, genes involved in fatty acid chain elongation and genes of the polyamine transporter operon. Conclusions Altered expression of these genes reflects a protective response to perturbation of the bacterial cell wall by penicillin. Such genes may represent potential therapeutic targets for enhancing the activity of penicillin against this organism and provide insight into novel mechanisms of penicillin resistance. [ABSTRACT FROM AUTHOR]