Comparison and evaluation of laboratory diagnostic method -smear, culture, molecular- in the fungal infection(Aspergillus, Dermatophyte and Mucor)

Aim and Alarming increase in fungal infections, especially in immunocompromised patients against the infectious agents and the vast advances in diagnostic methods of such diseases, causing extensive investigations for the diagnosis of fungal infections with more modern methods in different groups of patients. Our main objective is to evaluate and compare methods of laboratory diagnosis of smear-culture-molecular in fungal infections (dermatophytes, Aspergillus, Mucor) in clinical samples.
since August 2014 to January 2015, 420 cases of suspected fungal infections, from the Razi Hospital, Baqiyatallah hospital and Massoud laboratory were collected. Smear preparation of the samples was carried out and on the basis of these findings, type of lesion and diagnosed by specialists, samples are grouped. Culture and molecular methods (PCR and PCR-Sequencing) at the same time was performed.
Of the 420 samples analyzed by direct smear, 15 (5/3%) of Aspergillus, 64 samples (15/2%) of dermatophytes and zero sample of Mucor were identified. In 15 specimens of Aspergillus, 12 samples (80%) consisted with positive cultures and 3 cases (20%) were negative and based on Nested PCR results, all of 15 samples were positive. Of 64 samples of dermatophytes, 40 cases (62/5%) were positive by culture method and 16 cases (25%) were negative. 6 samples (3/9%) consisted with saprophytic contamination and 2 samples (12/3%) showed Aspergillus growth at the injection site, respectively. Based on Nested PCR method, 62 samples (8/96%) showed positive result.
The results of this study indicate that the PCR, with respect to its high sensitivity, bearings good capabilities for detection of fungal disease in the early stages of infection. Since the rapid and specific diagnosis of fungal infections, especially with regard to the genera and species of the fungal organisms, provide the possibility of proper and adequate applying of antifungal therapy protocols. Thus in this context, appropriate performance of rapid, specific and sensetive techniques would be necessary and inevitable.