Dietary sugars, serum and the biocide chlorhexidine digluconate modify the population and structural dynamics of mixed Candida albicans and Escherichia coli biofilms.

Despite the increasing recognition of the role played by mixed species biofilms in health and disease, the behavior and factors modulating these biofilms remain elusive. We therefore compared the effect of serum, two dietary sugars (sucrose and galactose) and a biocide, chlorhexidine digluconate, on a dual species biofilm (DSB) of Candida albicans and Escherichia coli and, their single species biofilm (SSB) counterparts. Both modes of biofilm growth on polystyrene plastic surfaces were quantified using a viable cell count method and visualized using confocal scanning laser microscopy (CSLM). Present data indicate that co-culture of C. albicans with varying initial concentrations of E. coli leads to a significant inhibition of yeast growth (r=-0.964; p<0.001). Parallel ultrastructural studies using CSLM and a Live/Dead stain confirmed that E. coli growth rendered blastospores and hyphal yeasts non-viable in DSB. SSB of C. albicans showed pronounced growth when its growth surface was pretreated with serum and by sugar supplements in the incubating medium (p<0.05). Intriguingly, C. albicans in DSB was more resistant to the antiseptic effect of chlorhexidine digluconate. Taken together, the current data elucidate some features of the colonization resistance offered by bacteria in mixed bacterial/fungal habitats and how such phenomena may contribute to the development of fungal superinfection during antimicrobial therapy.

Gingival enlargement as a diagnostic indicator in leukaemia. Case report.

The acute leukaemias are a group of neoplastic diseases that are characterized by proliferation of immature white cells in the bone marrow and/or blood and are often associated with severe leukopenia, anaemia and thrombocytopenia. Oral manifestations are more common in patients with acute leukaemia. Oral bleeding, gingival enlargement, ulceration and infection in patients with leukaemia have been described. Leukaemic infiltrates in the gingivae are commonly seen in acute monocytic leukaemia. A case of acute monocytic leukaemia in a 34-year-old female who reported with gingival enlargement is presented here. The role of oral lesions as a diagnostic indicator is discussed.