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

Interaction between caspofungin or voriconazole and cefoperazone-sulbactam or piperacillin-tazobactam by in vitro and in vivo methods

Immunosuppressive patients are at risk of fungal and bacterial infections. Therefore, these patients receive prophylactic, preemptive, empirical or target antifungal and concomitant antibiotic therapy. To this end, caspofungin (CAS) or voriconazole (VRC) antifungals and cefoperazone-sulbactam (CPZ/SAM) or piperacillin-tazobactam (PIP/TAZ) antibiotics may be used. Here, we aimed to investigate the interaction between these antifungals and antibiotics by in vitro and in vivo methods. The interaction was tested by chequerboard analysis and fractional inhibitory concentration index (FICI). It was also tested in a neutropenic mice-invasive candidiasis model and evaluated by fungal burden in kidney tissue of infected animals from the first day to the fifth day of treatment with 24h intervals. A synergism was detected between CAS and CPZ/SAM (FICI=0.1) and PIP/TAZ (FICI=0.3). Fungal burden in tissues of drug-treated mice was reduced compared with controls in a time-dependent manner. In comparison with CAS-alone treated group, there were 1.32log(10) reductions of fungal burden in CAS+CPZ/SAM (p=0.002) and in CAS+PIP/TAZ group (p=0.14). The same interactions were not found with VRC and antibiotics. CPZ/SAM had stronger synergistic interaction with CAS than PIP/TAZ. The mechanism of synergism is not well understood. This is most likely due to an increase in the anticandidal effect of CAS plus antibiotics