EVALUATION OF DIFFERENT CULTURE MEDIA AND INCUBATION TIMES FOR THE GERM TUBE TEST IN CANDIDA ALBICANS

Abstract

Germ tube test is a rapid and cost-effective method for the presumptive identification of Candida albicans in routine clinical laboratories, but its performance depends on both the testing medium and incubation time. In this study, 40 clinical isolates of C. albicans were evaluated for germ tube formation using six different media, including human plasma, rabbit plasma, 1% peptone casein, 1% peptone meat, Brain Heart Infusion, and Tryptic Soy Broth at incubation times of 2, 4 and 6 hours. Human plasma and rabbit plasma showed the highest sensitivity, yielding 100% germ tube positivity at 2 hours. Among the alternative media, 1% peptone meat and TSB demonstrated relatively high early positivity rates (85%), whereas BHI and 1% peptone casein exhibited substantially lower sensitivity. Prolonged incubation beyond 2 hours resulted in a marked decline in germ tube positivity across all media, indicating an increased risk of false-negative results. These findings confirm that plasma-based media remain the most reliable substrates for germ tube induction in C. albicans. However, 1% peptone meat and TSB represent practical low - cost alternatives when results are interpreted at the optimal 2 - hour time point.