Engin Kaplan

Dishwashers are a major source of human opportunistic yeast-like fungi in indoor environments in Mersin, Turkey

The natural habitat of opportunistic fungal pathogens is outside of the host; therefore, it is crucial to understand their ecology and routes of transmission. In this study, we investigated the presence of black and filamentous fungi in moist indoor environments in the city of Mersin in subtropical Turkey. In total, 177 private dwellings were screened and 893 samples obtained using cotton swabs and moistened with physiological saline from dishwashers, washing machines, refrigerators, bath-tubs, bathroom walls, and shower heads. These were then inoculated onto malt extract agar supplemented with chloramphenicol, followed by incubation at 37°C. Thirty samples (3.4%) were positive for fungi, which were then identified by sequencing the rDNA internal transcribed spacer region. Exophiala dermatitidis was the most common species (23), followed by E. phaeomuriformis (three), Magnusiomyces capitatus (two), and Candida parapsilosis (two). Genotype A of E. dermatitidis (14) was more prevalent than genotypes B (eight) and C (one) and E. phaeomuriformis was also represented by two genotypes. Our findings suggest that dishwashers are a major indoor niche for thermophilic black yeasts. The occurrence of the opportunistic filamentous fungus M. capitatus in dishwashers is consistent with a recent report.

Epidemiology of dermatophytosis in junior combat and non-combat sports participants.

Participation in competitive sports is popular and widely encouraged worldwide. Herein, we investigated 252 male and 67 female sports players, aged 16.4 ± 1.3 years, active in 15 different types of combat (n = 143) and non‐combat (n = 176) sports. Of the 319 participants in this study, 11 (3.5%) players, including six wrestlers, four football players and one handball player, all of whom were men, harboured dermatophytic fungi. Briefly, Trichophyton tonsurans was present in three athletes, who were scalp carriers of the fungus. Furthermore, T. rubrum (4), T. interdigitale (3) and Arthroderma simii (1) were recovered from eight participants with tinea inguinalis (4), tinea pedis (2) or both (1). One patient was a trunk carrier of concomitant tinea pedis. All dermatophytic fungi were identified using both direction sequence of the rDNA regions spanning the internal transcribed spacers (ITS1 and ITS2) and 5.8 rRNA gene. Although sports‐active individuals are active and sweat more, we observed a low prevalence of dermatophytosis, both in combat (5.2%) and non‐combat sports participants (3.4%) (P > 0.05). However, dermatophyte infections require more attention and appropriate management to eradicate the infection and to prevent possible outbreaks. This study also documents the first case of zoophilic A. simii in Turkey.

Design of potent fluoro-substituted chalcones as antimicrobial agents

Abstract Owing to ever-increasing bacterial and fungal drug resistance, we attempted to develop novel antitubercular and antimicrobial agents. For this purpose, we developed some new fluorine-substituted chalcone analogs (3, 4, 9–15, and 20–23) using a structure–activity relationship approach. Target compounds were evaluated for their antitubercular efficacy against Mycobacterium tuberculosis H37Rv and antimicrobial activity against five common pathogenic bacterial and three common fungal strains. Three derivatives (3, 9, and 10) displayed significant antitubercular activity with IC50 values of ≤16,760. Compounds derived from trimethoxy substituent scaffolds with monofluoro substitution on the B ring of the chalcone structure exhibited superior inhibition activity compared to corresponding hydroxy analogs. In terms of antimicrobial activity, most compounds (3, 9, 12–14, and 23) exhibited moderate to potent activity against the bacteria, and the antifungal activities of compounds 3, 13, 15, 20, and 22 were comparable to those of reference drugs ampicillin and fluconazole.

Molecular Diagnostics of Arthroconidial Yeasts, Frequent Pulmonary Opportunists

ABSTRACT Magnusiomyces capitatus and Saprochaete clavata are members of the clade of arthroconidial yeasts that represent emerging opportunistic pulmonary pathogens in immunocompromised patients. Given that standard ribosomal DNA (rDNA) identification often provides confusing results, in this study, we analyzed 34 isolates with the goal of finding new genetic markers for classification using multilocus sequencing and amplified fragment length polymorphism (AFLP). The interspecific similarity obtained using rDNA markers (the internal transcribed spacer [ITS] and large subunit regions) was in the range of 96 to 99%, whereas that obtained using protein-coding loci (Rbp2, Act, and Tef1α) was lower at 89.4 to 95.2%. Ultimately, Rbp2 was selected as the best marker for species distinction. On the basis of cloned ITS data, some strains proved to be misidentified in comparison with the identities obtained with phenotypic characters, protein sequences, and AFLP profiles, indicating that different copies of the ribosomal operon were present in a single species. Antifungal susceptibility testing revealed that voriconazole had the lowest MIC against M. capitatus, while amphotericin B had the lowest MIC against S. clavata. Both species exhibited in vitro resistance to fluconazole and micafungin.

Klinik ve Çevresel Exophiala İzolatlarında Biyosurfaktan Üretiminin Karşılaştırılması

Black yeast in the genus Exophiala are able to grow in hydrocarbon-contaminated environments and are pathogenic in immunosuppressed hosts. The biosurfactant produced by Exophiala species may be associated with strain pathogenicity by changing the hydrophobicity. The aim of this study was to prove the hypothesis that biosurfactant production in Exophilia strains isolated from clinical samples is lower than the strains isolates from toxic (dishwasher and railway sleepers) environments. A total of 122 Exophiala isolates 108 environmental (isolated from 82 dishwashers and 36 railway sleepers) and 14 clinical isolates confirmed by molecular tests were included in the study. Biosurfactant activity was tested by the drop collapse method, in which the surface of a microtiter plate well was evaluated for the presence of a biosurfactant, and by the oil spreading technique on crude oil. An open source analyses program, ImageJ®, was used for crude oil spreading technique data. A clear surface zone that differs more than two standard deviations from the mean size was accepted as a positive result. Among the 122 Exophiala species, 11 (9.0%) and 10 (8.2%) strains showed biosurfactant activity by the drop collapse test and oil spreading method, respectively. An acceptable relation was found between the drop collapse test and oil spreading method (Cohen κ coefficient= 0.30). Despite the presence of isolates showing biosurfactant activity, no statistically significant difference was detected between Exophiala strains (p= 0.72). The biosurfactant levels of environmental isolates were higher than the isolates obtained from the patients (p= 0.03). The highest biosurfactant level was observed in one Exophiala phaeomuriformis strain isolated from a dishwasher. There was no difference between the biosurfactant levels of the dishwasher and railway sleeper isolates (p= 0.66). Biosurfactant production may be a more important determinant of virulence in Exophiala species than expected. In this study, biosurfactant activity was higher in environmental isolates compared to the clinical isolates. Consensus of multiple biosurfactant screening protocols may clarify why environmental Exophiala species are less virulent. Further studies should evaluate biosurfactant activity in additional clinical Exophiala isolates. The biosurfactant activity of more Exophiala isolates obtained from patients should be investigated with further planned studies.

Comparison of the rolling circle amplification and ligase-dependent reaction methods for the identification of opportunistic Exophiala species

We developed two ligase-dependent probe amplification assays based on rolling circle amplification (RCA) and the ligase-dependent reaction (LDR) to differentiate species of Exophiala targeting the rDNA internal transcribed spacer region. We focused on Exophiala dermatitidis and E. phaeomuriformis, two opportunistic inhabitants of indoor wet cells, and further detected E. heteromorpha, E. xenobiotica, and E. crusticola; 57 reference isolates representing the five species were tested. Depending on the RCA probes used, the sensitivity was 100%, and the specificity ranged from 3.7% to 88.6% (median: 46.1%). In contrast, the sensitivity and specificity of the LDR probes targeting the same isolates were 88.6-100% (median: 95.8%) and 95.4-100% (median: 97.7%), respectively. We analyzed 198 additional environmental isolates representing the same Exophiala species. Overall, the sensitivity and specificity of LDR ranged from 89.7% to 100% (median: 94.1%) and from 93.9% to 100% (median: 96.9%), respectively. The assessment of performance and validation of LDR probes using SYBR Green quantitative polymerase chain reaction revealed high reproducibility and an acceptable range limit, in line with the guidelines of the European Network of GMO Laboratories. In conclusion, the LDR assay was more reliable and less expensive than RCA for species-level identification of Exophiala isolates.

Detection of hepatitis B virus X gene and PreC promoter mutations from chronic hepatitis B patients in the south of Turkey

Hepatitis B virus (HBV) infection is a global health problem with more than 2 billion infected individuals. HBV infection leads to diverse outcomes ranging from acute to chronic hepatitis, which may result in severe complications as liver cirrhosis and hepatocellular carcinoma (HCC). HBV is one of the most important human DNA viruses having strong oncogenic potential. Recently, many studies have reported on HBV X gene and PreC promoter mutations associated with HCC. In order to detect the prevalence of HBx gene and PreC promoter mutations possibly related to HCC, we have analyzed sera samples collected from 61 patients with chronic hepatitis B. We have detected T1653 mutation in 1 of 61 (1.63%), A1896 mutation in 10 of 61 (16.39%), and T1762-A1764 dual mutation in 4 of 61 (6.55%). T1653 and T1762-A1764 dual mutations were suggested significantly related to HCC in earlier reported studies. Our findings demonstrate that HBx gene and PreC promoter mutations related to HCC are present in our region and prospective clinical chord studies would be useful for better patient management and of early diagnosis of possible HCC cases.