Rapid Identification Of The Most Common Candida Species To Guide Early Antifungal Therapy For Candidemia

Transcription

1 Rapid Identification Of The Most Common Candida Species To Guide Early Antifungal Therapy For Candidemia 快速识别最常见的念珠菌种, 以指导早期抗真菌治疗 Dr. Fann Wu, Columbia University Medical Center New York, USA

2 CANDIDEMIA 念珠菌血症 4 th most common cause of hospitalassociated bloodstream infections Incidence - 8 infections per 10,000 persons annually Mortality 20-50% 死亡率 Often associated with disseminated disease Systemic as in septicemia, endocarditis and meningitis

3 CANDIDEMIA At risk populations 高危人群 ICU pts Prior colonization Central venous catheters Broad spectrum antibiotics Neutropenia (<1000 neutrophils/µl)

4 ETIOLOGICAL AGENTS Candida albicans 白色念珠菌 Candida glabrata 球拟酵母念珠菌 Candida tropicalis 热带假丝酵母菌 Candida krusei 克鲁斯假丝酵母菌 Candida parapsilosis 近平滑假丝酵母菌

5 Early Identification Guides Rx Rapid and accurate identification of the most common Candida species is essential to guide treatment. The laboratory plays a critical role in helping the clinician develop antibiotic usage strategies.

6 CANDIDEMIA CULTURE DX Stains KOH & Gram Periodic Acid-Schiff 过碘酸雪夫染色 (PAS) Culture Usually 1-5 Days To ID Non Selective Media -SAB Selective Media Chromagar Bird Seed Agar ID & Antifungal Susceptibility Microscan, API, Sensititer

7 C. albicans on SAB COLONIAL MORPH MICROSCOPIC OVOID BLASTOCONIDIA

8 POST-MORTEM ESOPHAGUS C. albicans Invasion of Blood Vessel Note blastoconidia & pseudohyphae

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12 C. ALBICANS & FLUCONAZOLE Etest & DISK Test

13 NEW TECHNOLOGY AdvanDx PNA FISH TM Rapid Pathogen ID for Candidemia Peptide Nucleic Acid Fluorescence In Situ Hybridization 肽核酸荧光原位杂交技术 Assays C. albicans test (GREEN IS POSITIVE) C. albicans (GREEN) & C. Glabrata (RED) Yeast traffic light (5 candida species) Test directly from newly positive blood culture bottles

14 PNA FISH Targets rrna

15 PNA FISH PROCEDURE 1. Fix Onto microscope slide 2. Hybridize with PNA probe Incubate 55 c for 90 min 3. Wash & mount Remove excess probe 4. Examine - results

16 EXAMINATION Fluorescence Microscope using FITC/Texas Dual Band filter

17 C. albicans PNA FISH

18 ADVANTAGE FOR DIAGNOSIS Peptide Nucleic Acid Fluorescence In Situ Hybridization Fluorescent PNA probe hybridizes to ribosomal RNA (rrna) Blood culture ID in 2.5 hrs rrna is highly conserved molecule copies/cell (natural amplification)

19 CANDIDEMIA TRAFFIC LIGHT ASSAY CANDIDA SPECIES ID C.albicans, C.parapsilosis, C. tropicalis C. krusei, C. glabrata SAME DAY RESULTS C.albicans or C.parapsilosis = GREEN C.tropicalis = GOLD C. glabrata or C. krusei = RED FLUORESCENCE CONTROLS Positive = mixture of C.albicans, C. glabrata & C.tropicalis Negative = No fluorescence

20 CUMC CANDIDEMIA DATA Candida PERFORMANCE (# bottles) SENSITIVI & SPECIFIC PPV & NPV C. albicans (25) 100% 100% C. glabrata (15) 100% 100% C. parapsilosis (2) 100% 100% C. dublinensis (4) 100% 100% C. tropicalis (6) 100% 100% C. krusei (2) 100% 100%

21 CUMC CANDIDEMIA DATA Candida sp PREVALENCE (%) TOTAL PEDS FLUCONAZOLE SUSCEPTIBILITY (%) C. albicans C. glabrata C. parapsilosis C. tropicalis C. krusei 3 6 0

22 CANDIDEMIA RX ANTIFUNGAL COST NEPHROTOXICITY AMPHOTERICIN B ( 两性霉素 B) VERY LOW HIGH FLUCONAZOLE ( 氟康唑 ) LOW VERY LOW CASPOFUNGIN ( 卡泊芬净 ) EXPENSIVE VERY LOW

23 CANDIDEMIA RX First-Line Therapy PNA FISH Results Therapy C. albicans Appropriate Fluconazole C. parapsilosis C. tropicalis Appropriate Caspofungin C. albicans C. krusei C. glabrata Inappropriate Expensive Correct

24 ADVANTAGES TO EARLY DETECTION OF CANDIDEMIA Tendency to treat empirically with broad spectrum antifungal agents such as caspofungin Selection appropriate antifungal therapy C.albicans vs non-c. albicans Slow development of fluconazole resistance Seriously ill patients: cannot afford delay

25 IDSA Guidelines - Candidemia Knowledge of the infecting species is highly predictive of likely susceptibility and can be used as a guide to therapy. * Fluconazole can be used as initial therapy for C. albicans IDSA Guidelines* Antifungal Cost Nephrotoxicity Fluconazole Low Very Low 12 companies to market generic version of Fluconazole *Pappas et al. Clinical Infectious Diseases. 2004;38: Johns Hopkins Antibiotics Guide: FDA Generic Approvals July 2004:

26 Candidemia Treatment Strategies 55% of candidemia s due C. albicans 2.5 hrs. ID directly from positive Blood Cultures: C. albicans vs. non-c. albicans Support appropriate antifungal selection Fluconazole can be used as initial therapy for C. albicans IDSA Guidelines* Broad-spectrum agents should be considered for non-c. albicans yeast IDSA Guidelines* *Pappas et al. Clinical Infectious Diseases. 2004;38:161-89

27 CONCLUSION Bloodstream infections are associated with high hospital cost and high morbidity and mortality 血流感染会给医院带来高成本以及高发病率和高死亡率 The results provide clinicians important information for patient therapy and supports appropriate use of antibiotics 快速检验结果可以为临床医师提供重要信息, 为病人的治疗和抗生素的适当使用提供依据 Rapid and accurate identification of Candida species directly from positive blood culture bottles saves life 直接从血培养阳性瓶中快速准确的鉴定出念珠菌种可为临床治疗争取时间挽救生命

28 THANK YOU