The effect of oral bacteria on Candida albicans germ-tube formation

A total of eight bacterial isolates belonging to six species, and a select group of 12 oral Candida albicans isolates, were used to study the effect o f bacteria on germ-tube formation. Briefly, each bacterial suspension (10(5 -6) cells/ml) was mixed with a C. albicans suspension (10(7) cells/ml) and incubated at 37 degreesC for 90 min with bovine serum, and the percentage g erm-tube-positive Candida cells was quantified using a haemocytometer, unde r light microscopy. In general, out of eight bacteria, Streptococcus sangui s SK21A, Streptococcus salivarius SK56, Escherichia coli ATCC 25922, and S. salival ius OBU3 suppressed germ-tube formation to varying degrees, with d ifferent C. albicans isolates. Porphyromonas gingivalis Pg 50, Lactobacillu s casei ATCC 7469 and Prevotella intermedia OBU4 elicited significant enhan cement of germ-tube formation, whereas S. sanguis OBU2 had no effect. E. co li ATCC 25922 was the only organism to show statistically significant suppr ession of germ-tube formation (p = 0.0312). A significant increase in the g erm tube production of C. albicans isolated from HIV-infected compared with HIV-free individuals was also noted. The current results tend to suggest t hat commensal and transient oral bacterial populations may selectively infl uence the differential expression of germ-tube-forming ability of C. albica ns isolates.