Does Alkaline Colonic pH Predispose to Clostridium difficile Infection?

OBJECTIVES: Clostridium difficile caused nearly 500,000 infections and was associated with approximately 29,000 deaths in 2011, according to data from the Centers for Disease Control and Prevention. C. difficile is a bacterium that causes diarrhea and, often, severe illness in healthcare facilities, as well as the community. Our objective was to determine whether alkaline colonic pH predisposes to colonization and infection with C. difficile. METHODS: A total of 228 patients with diarrhea and/or abdominal pain, leukocytosis, and fever were included. Stool pH was measured, and C. difficile antigen and toxin in stool were detected. RESULTS: Of 228 patients, 30 (13.2%) tested positive for C. difficile (antigen+/toxin+) and 171 (75%) were C. difficile negative (antigen-/toxin-). Of 171 patients who tested negative, 93 (54.4%) had stool pH >7.0 and 78 (45.6%) had pH ≤7.0. Among the 30 patients who tested positive, 26 (86.7%) had stool pH >7.0 (P = 0.002). Among the 27 colonized patients (antigen+/toxin-), 12 (44.4%) had stool pH >7.0 (P = 0.34). For all patients with stool pH ≤7.0, 96% tested negative for C. difficile infection (P = 0.002). CONCLUSIONS: A strong association between C. difficile infection and alkaline stool pH was found.

Scanning Acoustic Microscopy Comparison of Descemet's Membrane Normal Tissue and Tissue With Fuchs' Endothelial Dystrophy.

Purpose: To describe the application of scanning acoustic microscopy in the GHz-range (GHz-SAM) for qualitative imaging and quantitative characterization of the micromechanical properties of the Descemet's membrane and endothelial cells of cornea tissue. Methods: Investigated were samples of a normal tissue and a tissue with Fuchs' endothelial dystrophy (FECD, cornea Guttata). Descemet's membranes were fixed on glass substrates and imaged utilizing a focused acoustic lens operating at a center frequency of 1 GHz. Results: GHz-SAM data, based on the well-established V(z) technique, revealed discrepancies in the velocity of the propagation of Rayleigh surface acoustic waves (RSAW). RSAW were found to be slower in glass substrates with FECD samples than in the same glass substrates (soda-lime) with normal Descemet membrane, which indicates lower shear and bulk moduli of elasticity in tissues affected by FECD. Conclusions: Noninvasive/nondestructive GHz-SAM, is utilized in this study for the imaging and characterization of Descemet membranes, fixated on glass substrates. V(z) signatures containing sufficient oscillations were obtained for the system of Descemet membranes on glass substrates. The observed variation in the microelastic properties indicates potential for further investigations with GHz-SAM based on the V(z) technique.