Comparison of Neisseria gonorrhoeae minimum inhibitory concentrations obtained using agar dilution versus microbroth dilution methods.

With increasing antibiotic resistance observed amongst clinical isolates of Neisseria gonorrhoeae, the second most prevalent sexually transmitted bacterial disease in the United States, there is still a need for antimicrobial susceptibility testing (AST). The current method recommended by the Clinical and Laboratory Standards Institute is agar dilution. In this study, we show that a commercially available version of Fastidious Broth is capable of supporting N. gonorrhoeae in the evaluation of minimum inhibitory concentrations of 4 antibiotics (ceftriaxone, azithromycin, ciprofloxacin, and tetracycline), when comparing the agar dilution (AD) versus microbroth dilution (MBD) method and the susceptibilities obtained for 32 N. gonorrhoeae isolates. Herein, 3 out of the 4 antibiotics tested showed 94% or greater essential agreement (EA) and 91% or greater categorical agreement (CA) respectively, when comparing the MBD versus AD methods.

Impact of Fungal MAPK Pathway Targets on the Cell Wall.

The fungal cell wall is an extracellular organelle that provides structure and protection to cells. The cell wall also influences the interactions of cells with each other and surfaces. The cell wall can be reorganized in response to changing environmental conditions and different types of stress. Signaling pathways control the remodeling of the cell wall through target proteins that are in many cases not well defined. The Mitogen Activated Protein Kinase pathway that controls filamentous growth in yeast (fMAPK) was required for normal growth in media containing the cell wall perturbing agent Calcofluor White (CFW). A mass spectrometry (MASS-SPEC) approach and analysis of expression profiling data identified cell wall proteins and modifying enzymes whose levels were influenced by the fMAPK pathway. These include Flo11p, Flo10p, Tip1p, Pry2p and the mannosyltransferase, Och1p. Cells lacking Flo11p or Och1p were sensitive to CFW. The identification of cell wall proteins controlled by a MAPK pathway may provide insights into how signaling pathways regulate the cell wall.

A proteomic and genetic analysis of the Neurospora crassa conidia cell wall proteins identifies two glycosyl hydrolases involved in cell wall remodeling.

A proteomic analysis of the conidial cell wall identified 35 cell wall proteins. A comparison with the proteome of the vegetative hyphae showed that 16 cell wall proteins were shared, and that these shared cell wall proteins were cell wall biosynthetic proteins or cell wall structural proteins. Deletion mutants for 34 of the genes were analyzed for phenotypes indicative of conidial cell wall defects. Mutants for two cell wall glycosyl hydrolases, the CGL-1 ß-1,3-glucanase (NCU07523) and the NAG-1 exochitinase (NCU10852), were found to have a conidial separation phenotype. These two enzymes function in remodeling the cell wall between adjacent conidia to facilitate conidia formation and dissemination. Using promoter::RFP and promoter::GFP constructs, we demonstrated that the promoters for 15 of the conidia-specific cell wall genes, including cgl-1 and nag-1, provided for conidia-specific gene expression or for a significant increase in their expression during conidiation.