İmmün sistemi baskılı hastaların klinik örneklerinden soyutlanan Candida türlerinin PCR ile belirlenmesi ve antifungal direnç genlerinin RFLP ve sekans analizi ile saptanması

Amaç: Bu çalışmanın amacı immun sistemi baskılı hastalardan elde edilen klinik örneklerden izole edilen Candida türlerinde PCR tekniğinin ve RFLP ve sekans analizi ile antifungal direnç genlerinin araştırılmasıdır. Gereç ve yöntem: Çalışmada immün sistemi baskılı 200 hastadan alınan klinik örnekler (96 bronkoalveoler lavaj, 56 biyopsi-apse, 8 kan, 15 periton diyaliz sıvısı, 15 plevra sıvısı, 5 beyin omurilik ve 5 perikard sıvısı) geleneksel ve moleküler yöntemler ile incelenmiş ve sonuçlar değerlendirilmiştir. Örneklerden mantar DNA’sı saptandıktan sonra elde edilen ürünün, multipleks PCR yardımı ile tür düzeyinde tanısı yapılmış, antifungal direnci E-test, direnç genleri ise RFLP analizi ile saptanmıştır. Bulgular: İkiyüz örneğin 30’unda (%15) kültür yöntemleri ile pozitif sonuç alınmış [20 Candida albicans (%67), beş Candida parapsilosis (%17), beş Candida tropicalis (%17)], 170 (%85) örnekte üreme olmamıştır. Genel primerler ile yapılan PCR testi sonucunda kültürleri olumlu bulunan 30 örneğin tümünün mantar DNA’sı içerdiği belirlenmiştir. İzole edilen suşların biri E-test yöntemiyle flukanozole dirençli, ikisi flukanozole doza bağlı duyarlı olarak saptanırken 27’si duyarlı olarak bulunmuştur. Seçilen uygun primerler ile BamHI ve SalI enzimleri kullanılarak RFLP uygulanmış, yapılan analizler sonucunda dirençli bir C.albicans suşunda 600 bp’lik bant görülmüştür. Candida dubliniensis (950 bp) ve Candida krusei (360 bp) ile yapılan multipleks PCR optimizasyonunda başarı sağlanmıştır. Suşların ERG genine uygun primer çiftleri ile PCR’ları yapıldıktan sonra yapılan sekans analizi sonucunda dirençli C.albicans suşu referans gen ile karşılaştırıldığında D132E, E216D mutasyonları belirlenmiştir. Sonuç: Moleküler test yöntemleri özellikle immün sistemi baskılanmış hasta populasyonunun kısa sürede doğru tedavisine olanak sağladıkları için yaşamsal açıdan önemlidir.

The identification of Candida species isolated from clinical specimens of immunocompromised patients with PCR and determination of antifungal resistance genes with RFLP and sequencing analysis

Objectives: The aim of this study is to investigate PCR technique and antifungal resistance genes with RFLP and sequencing analysis in Candida species isolated from clinical specimens of immune-compromised patients. Materials and methods: Clinical samples (96 bronchoalveolar lavages, 56 biopsy-abscess, 8 blood specimens, 15 peritoneal fluid specimens, 15 pleural fluid, 5 cerebrospinal fluid and 5 pericard fluid specimens) from 200 immunosuppressed patients were studied by conventional and molecular methods. Antifungal susceptibility testing was performed by the E-test method. Firstly, fungal DNA was isolated from specimens, and then the resultant products are defined with multiplex PCR. Antifungal resistance and resistance genes were established by E-test and RFLP analysis. Results: Thirty of 200 samples (15%) were culture positive [20 Candida albicans (67%), five Candida parapsilosis (17%), five Candida tropicalis (17%)], and 170 of samples were found culture negative (85%). PCR with the universal primers detected fungal DNA in all 30 culture positive samples. One strain was determined as resistant; 2 strains were dose dependent susceptible and 27 strains were sensitive to fluconazole by E-test. The resistance gene (ERG11) was detected by BamHI and SalI enzymes revealed fluconazole resistance in one of C.albicans strains. The identification was successful in Candida dubliniensis (950 bp) and Candida krusei (360 bp) with multiplex PCR. D132E and E216D mutations were detected in sequencing of ERG 11 gene of this isolate and compared with reference gene in GenBank by clustal analysis. Conclusion: The molecular test methods supplies correct therapy rather early in immunosuppressive patients therefore it is important for the survival.

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