[Changing Trends in Isolation Frequencies and Species of Clinical Fungal Strains: What Do the 12-years (2008-2019) Mycology Laboratory Data Tell About?]

The frequency and variety of infections caused by fungi are increasing. However, changes and intercenter and regional differences are observed in the distribution of fungal species over the years. It is important to update the epidemiological data in order to enable early and appropriate treatment. In this retrospective study, the number of fungi isolated from clinical samples, their distribution at the genus/ species level and the variations over the years in Hacettepe University hospital which is a regional center for patients at risk of fungal infection were investigated. For this purpose, laboratory records from 2008- 2019 were examined and 21813 fungal strains isolated from 19636 clinical samples were detected. When the first (2008-2013) and second (2014-2019) six-year periods were compared, a 2.5 fold increase was observed in the number of specimens yielding fungal growth (first period; n= 5620, second period; n= 14016). Fungi were most frequently isolated from urine (45.0%), lower respiratory tract (30.7%) and blood (6.8%) samples. Mould isolation rate in all samples increased significantly in the second six-year period (from 8.3% to 10.6%, p≤ 0.001). As expected, the most frequent yeast was Candida albicans (57.0%) and mould was Aspergillus fumigatus complex (50.4%). In the second six-year period, isolation of C.albicans (59.3% to 56.0%, p≤ 0.001) among yeasts and A.fumigatus complex (58.1% to 48.0%, p≤ 0.001) among moulds decreased significantly. In urine specimens, most common fungi were C.albicans (49.8%), Candida glabrata complex (15.6%), Candida tropicalis (8.9%) and Candida kefyr (7.5%). In lower respiratory tract specimens, the most common mould was A.fumigatus complex (51.2%), which has decreased from 63.7% in the first six years to 47.1% in the second period (p≤ 0.001). Over the same period, other Aspergillus species (from 25.5% to 34.1%, p= 0.002) and non-Aspergillus moulds (from 36.3% to 52.9%, p≤ 0.001) were increased. In blood samples, C.albicans (44.4%), Candida parapsilosis complex (21.5%) and C.glabrata complex (13.0%) were the most frequent species. In the second six-year period, the frequency of C.albicans decreased from 47.3% to 42.2% (p= 0.059) and the frequency of C.glabrata complex increased from 9.5% to 15.5% (p≤ 0.001) when compared to the first period. For the sterile specimens other than blood, the most common species were C.albicans (37.8%), C.glabrata complex (9.1%) and C.parapsilosis complex (4.7%). However, the number of fungal isolates and the distribution of the species showed great variation over the years. In our center, a substantial increase in the number of fungal strains isolated from the clinical specimens were observed over a 12-years period. In addition and similar to previously published reports, the increase of strains belonging to species with decreased antifungal susceptibility and/or species with unknown susceptibility were detected. The use of local data is required in order to implement early and appropriate antifungal treatment because of inter-center and regional differences observed in epidemiological trends regarding the distributions of fungal genera and species. Surveillance studies to be conducted with the participation of large and sufficient numbers of centers in our country, as we have done for our center, will also contribute to approaches regarding the management of fungal infections by revealing the epidemiological data in a comprehensive manner.