Clinical and microbial epidemiology of otomycosis in the city of Yasuj, southwest Iran, revealing Aspergillus tubingensis as the dominant causative agent.

PURPOSE: Otomycosis is a mycotic infection of the external auditory canal and can be caused by a wide range of fungal species. In this study, we aimed to identify fungal isolates from patients suspected of otomycosis. METHODOLOGY: External ear canal samples were taken from patients referred to the outpatient department of Shahid-Mofatteh Clinic in the city of Yasuj, Iran, and examined by direct microscopy and culture. DNA of the isolated fungi was tested by internal transcribed spacer PCR restriction fragment length polymorphism analysis for identification of yeasts and ß-tubulin sequencing for identification of Aspergillus species. RESULTS: Among 275 patients suspected of otomycosis, 144 cases (83 female and 61 male) were confirmed with otomycosis. For 89% (n=128) of positive cultures, microscopy was also positive, while there were no cases with a microscopy-positive and culture-negative result. The predominant predisposing factor was self-cleaning of the external ear using unhygienic tools, and the main risk occupation was 'housewife'. The most common isolated fungi were typically Aspergillus (n=120), including 73 isolates of Aspergillus section Nigri, 43 of section Flavi, 3 of section Terrei and 1 of section Fumigati. After sequencing, 44 out of 73 strains primarily identified as Aspergillus niger turned out to be Aspergillus tubingensis. Thirty-five isolates were identified as Candida, including Candida parapsilosis (n=22), Candida albicans (n=12) and Candida tropicalis (n=1). CONCLUSION: Aspergillus tubingensis was the most common species involved in otomycosis. This work corroborates the difficulty of precise identification of species within the black Aspergilli by morphological characteristics.

Estimation of methane gas by LandGEM model from Yasuj municipal solid waste landfill, Iran.

CH4 has a high potential for energy production and by utilizing the proper technology, large amounts of energy can be extracted from it. This study aimed to estimate the amounts of methane emissions from the municipal solid waste landfill in Yasuj city using LandGEM software. The LandGEM model which is used for this aim is based on input data of open landfill year, land closure year, methane production rate, potential methane production capacity, and waste acceptance rate. According to the results, methane gas production during the years 2009, 2010, 2011 and 2012 was obtained to be 250, 275, 303, and 330 m3/h respectively. The results also showed that maximum methane production rate occurred during the years 2010-2012 and then reduced with a soft slope from 2012. The method and results of this research can be used for design and execute of methane gas collection systems and also, control of greenhouse gases emission for the landfills.