Evaluation Of Mueller-Hinton Agar For Germ Tube Test

Aims: The aim of this study is to evaluate Mueller-Hinton Agar (MHA) as a simple medium for the determination of germ tube test (GTT).Methods: A total of 86 Candida species isolated from different clinical specimens were included. All isolates were cultured onto Sabouraud Dextrose Agar (Salubris, Turkey) and incubated at 37°C for 24-48 hours. They were identified by VITEK MS (Biomérieux, France). For serum GTT, a single Candida colony was inoculated into 0.5 ml freshly obtained human serum. For MHA GTT, an inoculum of single colony was streaked by Dalmau technique onto MHA and covered by a sterile coverslip. After incubation at 37°C for 1.5 h and 3 h, all sera and MHA plates were examined using a light microscope. Serum GTT was accepted as gold standard method for the determination of sensitivity and specificity values.Results: The identification results were as follows: 51 Candida albicans, one C. dubliniensis, 12 C. parapsilosis, 12 C. glabrata, 4 C. kefyr, 3 C. tropicalis, 3 C. krusei. Serum GTT was positive in 30 (58.8%) and 36 (70.6%) of C. albicans isolates at 1.5 h and 3 h, respectively. MHA GTT was positive in 21 (41.2%) and 40 (78.4%) of C. albicans isolates at 1.5 h and 3 h, respectively. All non-albicans species except C. dubliniensis were found as negative using both tests. Both GTTs were positive for C. dubliniensis at 1.5 h and 3 h. MHA sensitivity and specificity was determined as 58% and 92% at 1.5 h; 86% and 81% at 3 h, respectively.Conclusions: MHA is safer and easier medium for GTT that may be used as alternative to serum GTT. The evaluation of GTT on MHA after 3 h incubation is recommended since it has higher sensitivity compared to 1.5 h