# Occurrence of Fungi on Duck Egg Shells and Drug Resistance Analysis of _Aspergillus_ spp. Isolates
## 4 Discussion
The microbiologically safest litter seems to be rice husks [24], but this bedding is not used in most countries. In fresh litter material, _Aspergillus fumigatus_ is the most often reported etiological agent of aspergillillosis, and in ducks, infections with _A. niger_ were also noted [10; 24; 25; 26]. The prevalence of _A. fumigatus_ on the duck eggs was 9.5%, and all isolates came from three flocks. The prevalence is low compared to other data from Egypt and Costa Rica (29-44%) [4; 27], but consistent with research of fungal contaminations of poultry litter in Portugal, where _Penicillium_ sp. was the most frequent genus noted (59.9%), followed by _Alternaria_ sp. (17.8%), _Cladosporium_ sp. (7.1%) and _Aspergillus_ sp. (5.7%) [25]. Our research shows the low risk of contamination and aspergillillosis development during the hatching process. Despite that, it is important to avoid the contamination of eggshells by spores and prevent embryo infections. Good litter management combined with assessment of its quality and the suitable collection and storage of eggs should be carried out. Control of the relative humidity in poultry houses and antifungal actions may be useful in order to control environmental contamination [5]. The spraying of antifungal agents like nystatin or copper sulfate [5; 28] contributed to decreases in fungal poultry litter contamination. Reports on the prevalence of aspergillllis in poultry and the resistance profiles of _A. fumigatus_ isolates are scarce. In our study, antifungal resistance towards three classes of drugs was examined--polyenes (ambhotericin B), azoles (titraconazole, posaconazole, voriconazole) and echinocandins (caspofungin). The antifungal resistance profiles of the isolates were various. Only two isolates (10.5%) were susceptible to all of the tested antifungal agents. Most of the isolates were resistant to itraconazole, which is opposite to the results obtained in the same country in 2015-2016 by [PERSON] et al. [29], and in France and China [30]. _A. niger_ strains showed a similar resistance to itraconazole, isolated from poultry before 2012 in Poland [31], but all of those isolates were susceptible to voriconazole, and most (80%) were susceptible to amphotericin B. These observations are also consistent with our research, in which a group of _A. fumigatus_ strains were susceptible to VOR (68.4%) and AMB (52.6%). The authors who investigated the drug resistance of _A. fumigatus_ in geese [6] noted that resistance to AMB ranged from 90.6 to 70.6%, and full susceptibility was noted for VOR and enilconazole. The _A. fumigatus_ isolated from Brazilian poultry also showed a high susceptibility to VOR (MIC range 0.5-32 ug/mL) and various resistance towards ITC (0.5-32.0 ug/mL) and AMB (0.5-8.0 ug/mL). The MIC values for CAS were 0.003-0.5 and were lower than observed in this investigation (0.19-32 ug/mL) [32]. The presence of _Aspergillus_ in the poultry food, litter, eggs and in the poultry house and hatchery carries implications not only for animal health and welfare but also public health, especially the health of farmworkers [4; 33; 34]. Our research showed that most of the _Aspergillus_ isolates (68.5%) were resistant to at least two antifungal agents. This is disturbing due to the possibility of human infection. Aspergillus is a disease which can cause respiratory signs in children, immunocompromised patients and allergy sufferers if they are exposed to high concentrations or repeatedly exposed to _Aspergillus_[33; 34]. In Europe, an antifungal resistance towards _A. fumigatus_ isolates was observed. AmphotericinB resistance was observed in 2.6% and 10.8% of isolates in Denmark and Greece, respectively. The prevalence of triazole resistance towards _A.fumigatus_ obtained from the included studies is 0.3% in Austria and 1% in Greece. The resistance in other countries was 1.2% in Switzerland, 2.1% in France, 3.9% in Portugal, 4.9% in Italy, 5.3% in Germany, 6.1% in Denmark, 7.4% in Spain, 8.3% in Belgium, 11% in the Netherlands and 13.2% in the United Kingdom [35].