Investigation of Biofilm Formation in Albicans and Non-Albicans Candida Species Obtained from Clinical Specimens and Distribution by Species

GİRİŞ ve AMAÇ: Candida türleri, dünya çapında hastane kaynaklı enfeksiyonların önemli nedenleri arasında kabul edilmektedir. Başlıca virülans faktörleri; biyofilm oluşumu, fosfolipaz ve asit proteaz üretimidir. Biyofilm üretimi türleri Candida'lar için önem taşımaktadır ve antifungal direnç ile ilişkilidir. Çalışmada; nonalbicans Candida'lar ve C. albicans türlerinde biofilm oluşumu araştırılmıştır. GEREÇ ve YÖNTEM: Çalışmaya, klinik örneklerden izole edilen 53 Candida suşu alındı. 37°C'de 48-72 saat inkübasyon sonrası sabouraud dekstroz agarda (SDA) saf olarak üretilen kolonilerin tiplendirilmesinde; mikroskopik değerlendirme, germ tüp testi, ve API ID 32C (bio Mérieux, Fransa) kullanıldı. Tüm şuslarda biyofilm üretimi araştırıldı. Biyofilm varlığı tespiti için glukozlu triptik soy broth (modifiye tüp adherens yöntemi) kullanıldı. BULGULAR: Elli üç Candida suşunun 34'ü (%64,1) C. albicans, 11'i (%20,7) C. parapsilosis, 4'ü (%7,5) C. kefyr, 3'ü (%5,6) C. tropicalis ve 1'i (%1,8) C. glabrata olarak saptandı. Tüm suşlar değerlendirildiğinde; biyofilm oluşumu % 47,2 olarak saptandı. Albicans türü Candida'larda %38,2 oranında, non-albicans Candida'larda ise %63,1 oranında biyofilm oluşumu gözlendi. C albicans suşlarının %38,2'inde (13), C parapsilosis suşlarınn %63,6'sinde (7), C. kefyr suşlarının %50'sinde (2), C. tropicalis suşlarının %66,6'sinde (2) ve bir C glabrata (1) suşunda biyofilm üretimi tespit edildi. Biyofilm pozitifliği gösteren suşların; %96'sının, servis ve yoğun bakımlarda yatmakta olan ve uzun süreli antibiyotik tedavisi alan hastalardan izole edildiği gözlendi. TARTIŞMA ve SONUÇ: Doğada mikrobiyal büyümede ve klinik enfeksiyonların gelişmesinde biyofilm oluşumu büyük önem taşımakta olup, mikroorganizmayı konak savunmasından ve antimikrobiyallerden korumaktadır. İlişkili mikroorganizmalarda antimikrobiyal direnç yüksektir. Son yıllarda invazif uygulamaların artışı ile fungal patojenler için risk artışı da söz konusudur. Nonalbicans kandidemilerin artışı ve biyofilm oluşumu artan antifungal dirence neden olmaktadır. Etken profili ve antimikrobiyal duyarlılıkta epidemiyolojik değişimler göz önüne alındığında Candida suşları da dikkatli şekilde değerlendirilmelidir. Etken dağılımı, biyofilm oluşumu, antifungal duyarlılık durumlarının bilinmesi, uygun tedavinin belirlenmesi, lokal verilerin ışığında ampirik tedavi seçimlerinin doğru yapılması ve sonuçlar açısından yararlı olacaktır.INTRODUCTION:Candida species are one of the important causes of hospital-acquired infections worldwide. Major virulence factors are; biofilm formation, phospholipase and acid protease production. Biofilm production are important for Candida species and associated with antifungal resistance. In the study; Biofilm formation in nonalbicans Candida and C. Albicans species was investigated. MATERIAL and METHOD: Fiftythree Candida species isolated from clinical specimens. Typing of purely produced colonies on sabouraud dextrose agar (SDA) after 48-72 hours incubation at 37° C; microscopic evaluation, germ tube test, and API ID 32C (bio Mérieux, France) were used. In all cases, biofilm production was investigated. Glucose tryptic soy broth (modified tube adherens method) was used to detect biofilm presence. RESULTS: Biofilm formation was observed in 38.2% of albicans Candida species and 63.1% in non-albicans Candida species. Of the thirty three candida species, 34 (64.1%) were C. albicans, 11 (20.7%) were C. parapsilosis, 4 (7.5%) were C. kefyr, 5,6) C. Tropicalis and 1 (1.8%) C. Glabrata were detected. When all species are evaluated; biofilm formation was found to be 47.2%. Biofilm production in C. Albicans 38.2% (13), in C. parapsilosis 63.6% (7), in C. kefyr 50% (2), in C. glabrata (1) was detected. Species showing biofilm positivity; 96% were isolated from patients receiving long-term antibiotic therapy in the service and intensive care unit. DISCUSSION and CONCLUSION: Biofilm formation is very important factor in microbial growth and in the development of clinical infections. It protects the microorganism from host defense and antimicrobials. Antimicrobial resistance is high in bacteria producing biofilms. In recent years, the risk for fungal pathogens has increased within invasive procedures. Non-albicans candidiasis and biofilm formation associated antifungal resistance. Considering the epidemiological changes in the efficacy profile and antimicrobial susceptibility, Candida species should also be evaluated carefully. Distribution of microorganism, biofilm formation, knowledge of antifungal susceptibility, local datas will be useful choices of empirical appropriate treatment

[Detection of virulence factors and antifungal susceptibilities of Fusarium strains isolated from keratitis cases].

Fusarium species have gained importance as a cause of keratitis. The pathogenicity and virulence factors of genus Fusarium remain largely unknown. Several putative virulence factors have been reported for fungal pathogens, including biofilm formation, production of proteinases and other hydrolytic enzymes. It has been emphasized that Fusarium species are generally resistant to antifungals but the resistance may vary depending on the species and even according to the isolate. For this reason, pathogenic features and antifungal susceptibility of the clinical isolates gained importance for the management of keratitis cases. The aim of this study was to identify clinical Fusarium isolates, to evaluate their virulence factors and to show antifungal susceptibility patterns. The identification of Fusarium was made on genus level isolated from 25 keratitis cases. Among them, 13 of the isolates were identified by ITS sequencing on species complex level. The production of hemolytic activity, caseinase, esterase, proteinase and phospholipase activity were investigated in 13 of the isolates. Biofilm production was searched among all 25 isolates. Galleria mellonella larvae was used as in vivo infection model. Antifungal susceptibility for amphotericin B, itraconazole, voriconazole and posaconazole was performed according to the Clinical and Laboratory Standards Institute (CLSI) M38-A2 microdilution assay guidelines. As the subcommittee on antifungal susceptibility tests did not determine the clinical resistance breakpoints (CBP) specific to Fusarium species complex, the epidemiological cut off values (ECV) were used for the interpretation of the minimum inhibitory concentration (MIC) values of the antifungal drugs. Isolates were identified as six F.oxysporum, six F.solani species complex and one F.brachygibbosum. One F.solani, one F.oxysporum were positive for hemolytic activity; all isolates were caseinase positive; three F.oxysporum and two F.solani isolate were esterase positive; one F.solani isolate was proteinase positive; five F.oxysporum and two F.solani isolates were phospholipase positive; biofilm activity was positive in 52% of the 25 isolates. The larvae survived for seven days after Fusarium inoculation in the G.mellonella larvae model. MIC range was 0.5-8 µg/ml for amphotericin B, 2-32 µg/ml for itraconazole, 0.5-8 µg/ml for voriconazole, 0.5-16 µg/ml for posaconazole and according to the ECV values F.solani and F.oxysporum isolates were determined as wild type for four antifungal agents. As a result, it was shown that Fusarium isolates have some virulence factors, there was a concordance between in vitro virulence properties and in vivo virulence characteristics and some of the isolates were classified as antifungal susceptible wild type isolates