Impact of sodium lactate as a carbon source in the polysaccharide of Cryptococcus species

Cryptococcosis is a systemic mycosis caused by fungi of the genus Cryptococcus, with the polysaccharide capsule serving as the primary virulence factor. In immunocompromised individuals, the fungus can disseminate to the central nervous system, leading to severe complications. This study investigates the morphological and physicochemical changes induced by sodium lactate in the polysaccharide capsule of Cryptococcus species. We observed alterations in cell growth and capsule expansion; however, the electrical and viscoelastic properties of the capsular polysaccharides did not show statistically significant changes across the lactate concentrations studied. Notably, hospitalized patients with cryptococcal meningitis receiving Ringer’s solution exhibited unfavorable clinical outcomes, including higher mortality rates compared to those treated with saline. These findings suggest that sodium lactate significantly impacts the morphology, structure, and proliferation of Cryptococcus species, influencing key factors such as capsule size and cell body size, which are critical for the fungus’s survival and dissemination. The reduction in capsule size in lactate-containing media may facilitate the spread of smaller cells to extrapulmonary tissues. Despite significant morphological changes, fluorescence microscopy confirmed that the chemical composition of the capsular polysaccharide remained unaltered, indicating that the effects are primarily quantitative. Furthermore, changes in the pH of the growth medium suggest that metabolic byproducts differ in the presence of lactate. These results underscore the need for enhanced clinical awareness regarding the use of lactated Ringer’s solution in cryptococcal infections, as lactate may exacerbate fungal virulence and resistance, highlighting the importance of understanding metabolic interactions when developing effective therapeutic strategies.