Viability Kinetic Profile, Morphological Structure, and Physicochemical Characterization of Candida albicans Biofilm on Latex Silicone Surfaces

Biofilm formed by Candida albicans on latex silicone surfaces was characterized by instrumental techniques such as fluorescence microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. The growth and viability of C. albicans on the biofilm formed were described using different kinetic rate equations. C. albicans biofilm has a complex and heterogenous structure with hyphal elements and yeast cells entrenched within a polysaccharide matrix. Spectroscopic studies revealed specific stretching frequencies of O-H, C-O, and C=O which can be attributed to the presence of some functionalities in the biofilm formed by C. albicans. Viability of C. albicans behaved in accordance with the first-order kinetic equation on the first 48 h, then shifted to a second-order kinetic equation until the 72 h, and had a doubling time of 70 h. Information on model biofilms with emphasis on growth rates and morphogenesis, structural organization, and physicochemical characteristics can possibly explain resistance to some antifungal treatments and subsequent synthesis of newer generation drugs for fungal biofilm-related infections.

Evaluation of buffy coat 16S rRNA PCR, buffy coat culture and whole blood PCR for detection of bacteraemia

The use of Gram type-specific PCR on buffy coat from clinical specimens for the detection of bacteraemia was evaluated for the first time using whole blood culture as the gold standard. In addition, the established buffy coat culture and whole blood PCR were also compared. Gram-positive bacteria belonging to six species and Gram-negative bacteria from 10 species were isolated and identified by culture and detected using broad-range 16S rDNA primers and Gram-specific primers. Data from the three methods all conferred very high sensitivity, specificity, positive and negative predictive values when compared to whole blood culture. The Kappa coefficients of agreement were 0.9819 (buffy coat PCR), 0.9458 (whole blood PCR) and 1.0 (buffy coat culture), which establishes their validity as alternative methods to routine blood culture in detecting bacteraemia. In addition, results showed that there was a direct correlation of WBC counts greater than 12,000 cells per mm³ to the occurrence of bacteraemia as detected by the four methods (p < 0.05).