scholarly journals Antifungal Susceptibly Testing by Concentration Gradient Strip Etest Method for Fungal Isolates: A Review

2019 ◽  
Vol 5 (4) ◽  
pp. 108 ◽  
Author(s):  
Eric Dannaoui ◽  
Ana Espinel-Ingroff
Keyword(s):  
Concentration Gradient ◽  
Susceptibility Testing ◽  
Fungal Infections ◽  
Antifungal Susceptibility ◽  
Antifungal Susceptibility Testing ◽  
Epidemiological Surveillance ◽  
Diffusion Method ◽  
Dilution Method ◽  
Strip Method

Antifungal susceptibility testing is an important tool for managing patients with invasive fungal infections, as well as for epidemiological surveillance of emerging resistance. For routine testing in clinical microbiology laboratories, ready-to-use commercial methods are more practical than homemade reference techniques. Among commercially available methods, the concentration gradient Etest strip technique is widely used. It combines an agar-based diffusion method with a dilution method that determinates a minimal inhibitory concentration (MIC) in µg/mL. Many studies have evaluated the agreement between the gradient strip method and the reference methods for both yeasts and filamentous fungi. This agreement has been variable depending on the antifungal, the species, and the incubation time. It has also been shown that the gradient strip method could be a valuable alternative for detection of emerging resistance (non-wild-type isolates) as Etest epidemiological cutoff values have been recently defined for several drug-species combinations. Furthermore, the Etest could be useful for direct antifungal susceptibility testing on blood samples and basic research studies (e.g., the evaluation of the in vitro activity of antifungal combinations). This review summarizes the available data on the performance and potential use of the gradient strip method.

scholarly journals Epidemiological and Microbiological Study of Onychomycosis

2021 ◽  
Author(s):  
Sunita Kabi ◽  
Bichitrananda Swain ◽  
Swati Jain
Keyword(s):  
Candida Species ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Nail Plate ◽  
Laboratory Diagnosis ◽  
Antifungal Susceptibility Testing ◽  
Antifungal Drugs ◽  
Diffusion Method ◽  
Resistance Pattern

Introduction: Onychomycosis is a common fungal infection of nail. It may be caused by dermatophytes, non-dermatophytic moulds or yeasts involving nail bed, nail plate or matrix of nail. As the fungi show variable susceptibility to antifungal drugs and treatment requires long duration of antifungal therapy, so it’s prevalence as well as proper laboratory diagnosis and antifungal susceptibility testing is essential for effective therapy. Aim: To find the prevalence of onychomycosis with demography along with various aetiology and the suitable antifungal drugs used for treatment. Materials and Methods: For this prospective study, over a period of two years a total of 300 nail samples were processed in the Department of Microbiology at IMS and SUM Hospital, Bhubaneswar, Odisha, India. The wet mount for microscopic examination was prepared using 20% Potassium Hydroxide (KOH) and examined after overnight incubation. Culture was done in duplicate in Sabouraud’s Dextrose Agar (SDA) tubes; one with actidione and another without it and both were incubated at 25°C in Biological Oxygen Demand (BOD) incubator. Culture tubes growing yeasts were further subjected to speciation by germ tube test, culture on Chromogenic (CHROM) agar and on cornmeal agar. In-vitro antifungal susceptibility testing was performed against Candida species using disc diffusion method on Muller Hinton agar. Chi-square test was used for statistical analysis of the results. Results: Onychomycosis can affect a wide age group though seen commonly at 31-40 years equally in both male and females. Fingernail infection was observed mostly in female cases. It was caused by Candida species (66%), moulds (24%) and dermatophytes (10%) and out of Candida sp. C.albicans was the main culprit. Although all the Candida strains were susceptible to amphotericin B, still some of them showed resistance to the commonly used antifungals like fluconazole and itraconazole. Conclusion:Candida albicans was the most common aetiological agent which contributed for onychomycosis and showed a variable resistance pattern to the commonly used antifungals. Proper laboratory diagnosis and selection of antifungal drug is essential prior to institution of therapy for successful treatment of this disease.

scholarly journals In vitro susceptibility testing of four antifungal drugs against fungal isolates in onychomycosis

2018 ◽  
Vol 6 (8) ◽  
pp. 2774 ◽  
Author(s):  
Smita S. Kulkarni ◽  
Jayshree B. Bhakre ◽  
Ajit S. Damle
Keyword(s):  
Amphotericin B ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Antifungal Susceptibility Testing ◽  
Antifungal Drugs ◽  
Etiological Agent ◽  
Diffusion Method ◽  
In Vitro Susceptibility ◽  
Broth Macrodilution

Background: Onychomycosis is chronic fungal infection of fingernails and toenails. Variety of fungi cause onychomycosis. Due to importance of high prevalence rate of onychomycosis this study was conducted.Methods: In this study 100 patients suspected of onychomycosis were examined. Diagnosis of onychomycosis was based on the patient’s history, physical examination, microscopy and culture of nail specimens.Results: Direct microscopy of the nail clippings in 20% KOH solution was positive in 61% and culture was positive in 54% cases. The common etiological agent was dermatophytes (79.6% cases) followed by non dermatophyte moulds (11.1% cases) and yeasts (9.2% cases). Amongst dermatophytes, T. rubrum was found to be commonest etiological agent (57.6%) followed by T. mentagrophytes. We had performed the in vitro antifungal susceptibility testing of isolated fungal species against Amphotericin B, Fluconazole, Itraconazole and Terbinafine according to standard guidelines recommended by the CLSI. Antifungal susceptibility testing of dermatophytes and non-dermatophyte moulds was performed by broth macrodilution method. For Candida species we used broth macrodilution method as well as disk diffusion method. All three Candida albicans isolates were sensitive to amphotericin B, fluconazole and itraconazole. Two strains of Candida krusei were sensitive to amphotericin B and resistant to fluconazole and itraconazole. Two isolates of T. rubrum had MIC >64µg/ml and one T. Mentagrophytes isolate had MIC 32µg/ml for fluconazole. Among non dermatophyte moulds, Aspergillus niger and one isolate of Fusarium oxysporum showed high MICs against fluconazole.Conclusions: Terbinafine exhibited the lowest MICs among all the tested antifungal drugs.

scholarly journals Role and Interpretation of Antifungal Susceptibility Testing for the Management of Invasive Fungal Infections

2020 ◽  
Vol 7 (1) ◽  
pp. 17
Author(s):  
Frederic Lamoth ◽  
Russell E. Lewis ◽  
Dimitrios P. Kontoyiannis
Keyword(s):  
Antifungal Therapy ◽  
Susceptibility Testing ◽  
Fungal Infections ◽  
Antifungal Susceptibility ◽  
Invasive Fungal Infections ◽  
Antifungal Susceptibility Testing ◽  
Candida Auris ◽  
Candida Spp ◽  
Neutropenic Patients

Invasive fungal infections (IFIs) are associated with high mortality rates and timely appropriate antifungal therapy is essential for good outcomes. Emerging antifungal resistance among Candida and Aspergillus spp., the major causes of IFI, is concerning and has led to the increasing incorporation of in vitro antifungal susceptibility testing (AST) to guide clinical decisions. However, the interpretation of AST results and their contribution to management of IFIs remains a matter of debate. Specifically, the utility of AST is limited by the delay in obtaining results and the lack of pharmacodynamic correlation between minimal inhibitory concentration (MIC) values and clinical outcome, particularly for molds. Clinical breakpoints for Candida spp. have been substantially revised over time and appear to be reliable for the detection of azole and echinocandin resistance and for outcome prediction, especially for non-neutropenic patients with candidemia. However, data are lacking for neutropenic patients with invasive candidiasis and some non-albicans Candida spp. (notably emerging Candida auris). For Aspergillus spp., AST is not routinely performed, but may be indicated according to the epidemiological context in the setting of emerging azole resistance among A. fumigatus. For non-Aspergillus molds (e.g., Mucorales, Fusarium or Scedosporium spp.), AST is not routinely recommended as interpretive criteria are lacking and many confounders, mainly host factors, seem to play a predominant role in responses to antifungal therapy. This review provides an overview of the pre-clinical and clinical pharmacodynamic data, which constitute the rationale for the use and interpretation of AST testing of yeasts and molds in clinical practice.

scholarly journals The Emerging Terbinafine-Resistant Trichophyton Epidemic: What Is the Role of Antifungal Susceptibility Testing?

Dermatology ◽  
2021 ◽  
pp. 1-20
Author(s):  
Julia J. Shen ◽  
Maiken C. Arendrup ◽  
Shyam Verma ◽  
Ditte Marie L. Saunte
Keyword(s):  
Gene Mutation ◽  
Susceptibility Testing ◽  
Geometric Mean ◽  
Antifungal Susceptibility ◽  
Antifungal Susceptibility Testing ◽  
Squalene Epoxidase ◽  
Exclusion Criteria ◽  
Huge Variation

<b><i>Background:</i></b> Dermatophytosis is commonly encountered in the dermatological clinics. The main aetiological agents in dermatophytosis of skin and nails in humans are <i>Trichophyton</i> (<i>T</i>.) <i>rubrum</i>, <i>T. mentagrophytes</i> and <i>T. interdigitale</i> (former <i>T. mentagrophytes-</i>complex). Terbinafine therapy is usually effective in eradicating infections due to these species by inhibiting their squalene epoxidase (SQLE) enzyme, but increasing numbers of clinically resistant cases and mutations in the SQLE gene have been documented recently. Resistance to antimycotics is phenotypically determined by antifungal susceptibility testing (AFST). However, AFST is not routinely performed for dermatophytes and no breakpoints classifying isolates as susceptible or resistant are available, making it difficult to interpret the clinical impact of a minimal inhibitory concentration (MIC). <b><i>Summary:</i></b> PubMed was systematically searched for terbinafine susceptibility testing of dermatophytes on October 20, 2020, by two individual researchers. The inclusion criteria were <i>in vitro</i> terbinafine susceptibility testing of <i>Trichophyton (T.) rubrum</i>, <i>T. mentagrophytes</i> and <i>T. interdigitale</i> with the broth microdilution technique. The exclusion criteria were non-English written papers. Outcomes were reported as MIC range, geometric mean, modal MIC and MIC<sub>50</sub> and MIC<sub>90</sub> in which 50 or 90% of isolates were inhibited, respectively. The reported MICs ranged from &#x3c;0.001 to &#x3e;64 mg/L. The huge variation in MIC is partly explained by the heterogeneity of the <i>Trichophyton</i> isolates, where some originated from routine specimens (wild types) whereas others came from non-responding patients with a known SQLE gene mutation. Another reason for the great variation in MIC is the use of different AFST methods where MIC values are not directly comparable. High MICs were reported particularly in isolates with SQLE gene mutation. The following SQLE alterations were reported: F397L, L393F, L393S, H440Y, F393I, F393V, F415I, F415S, F415V, S443P, A448T, L335F/A448T, S395P/A448T, L393S/A448T, Q408L/A448T, F397L/A448T, I121M/V237I and H440Y/F484Y in terbinafine-resistant isolates.

Use of spectrophotometric reading for in vitro antifungal susceptibility testing ofAspergillusspp.

1999 ◽  
Vol 45 (10) ◽  
pp. 871-874 ◽  
Author(s):  
Eric Dannaoui ◽  
Florence Persat ◽  
Marie-France Monier ◽  
Elisabeth Borel ◽  
Marie-Antoinette Piens ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Antifungal Susceptibility Testing ◽  
Aspergillus Species ◽  
National Committee ◽  
Broth Microdilution Method

A comparative study of visual and spectrophotometric MIC endpoint determinations for antifungal susceptibility testing of Aspergillus species was performed. A broth microdilution method adapted from the National Committee for Clinical Laboratory Standards (NCCLS) was used for susceptibility testing of 180 clinical isolates of Aspergillus species against amphotericin B and itraconazole. MICs were determined visually and spectrophotometrically at 490 nm after 24, 48, and 72h of incubation, and MIC pairs were compared. The agreement between the two methods was 99% for amphotericin B and ranged from 95 to 98% for itraconazole. It is concluded that spectrophotometric MIC endpoint determination is a valuable alternative to the visual reference method for susceptibility testing of Aspergillus species.Key words: antifungal, susceptibility testing, Aspergillus, spectrophotometric reading.

Vaginitis Due To Pichia fermentans in a Patient Affected by Endometrial Cancer: A Novel Case Report

2021 ◽  
Vol 17 ◽  
Author(s):  
Zarifeh Adampour ◽  
Malihe Hasanzadeh ◽  
Hossein Zarrinfar ◽  
Maryam Nakhaei ◽  
Monika Novak Babič
Keyword(s):  
Endometrial Cancer ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Female Genital Tract ◽  
Antifungal Susceptibility Testing ◽  
Vein Thrombosis ◽  
Microbial Infections ◽  
Life Threatening ◽  
In Vitro Antifungal Susceptibility

Introduction: Endometrial cancer is one of the most common malignancies of the female genital tract, which can be serious or life-threatening. Microbial infections can be one of the underlying causes of this type of cancer. Case Presentation: The present study describes the isolation of Pichia fermentans (Candida firmentaria var. firmentaria) from the vaginal secretions of a 61-year-old woman affected by endometrial cancer. She reported abdominal pain and vaginal discharge for 3 months, and had a history of diabetes, hypertension, Deep Vein Thrombosis (DVT), and Acute Myeloid Leukemia (AML). The isolated yeast was identified based on nuclear ribosomal internal transcribed spacer (ITS1-ITS2 rDNA) sequence analysis. The in vitro antifungal susceptibility testing showed a higher effect for ketoconazole against P. fermentans than fluconazole, itraconazole and voriconazole. Conclusion: Correct differentiation between P. fermentans and other yeast should be considered. The in vitro antifungal susceptibility testing is recommended for rare yeast, and will help the physicians in providing the best treatment.

scholarly journals Standardized Method for In Vitro Antifungal Susceptibility Testing of Candida albicansBiofilms

2001 ◽  
Vol 45 (9) ◽  
pp. 2475-2479 ◽  
Author(s):  
Gordon Ramage ◽  
Kacy Vande Walle ◽  
Brian L. Wickes ◽  
José L. López-Ribot
Keyword(s):  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Colorimetric Assay ◽  
Antifungal Susceptibility ◽  
Antifungal Susceptibility Testing ◽  
Phenotypic Traits ◽  
Salt Reduction ◽  
Treatment Regimens ◽  
In Vitro Antifungal Susceptibility

ABSTRACT Candida albicans is implicated in many biomaterial-related infections. Typically, these infections are associated with biofilm formation. Cells in biofilms display phenotypic traits that are dramatically different from those of their free-floating planktonic counterparts and are notoriously resistant to antimicrobial agents. Consequently, biofilm-related infections are inherently difficult to treat and to fully eradicate with normal treatment regimens. Here, we report a rapid and highly reproducible microtiter-based colorimetric assay for the susceptibility testing of fungal biofilms, based on the measurement of metabolic activities of the sessile cells by using a formazan salt reduction assay. The assay was used for in vitro antifungal susceptibility testing of severalC. albicans strains grown as biofilms against amphotericin B and fluconazole and the increased resistance of C. albicans biofilms against these antifungal agents was demonstrated. Because of its simplicity, compatibility with a widely available 96-well microplate platform, high throughput, and automation potential, we believe this assay represents a promising tool for the standardization of in vitro antifungal susceptibility testing of fungal biofilms.

Sign in / Sign up

Export Citation Format

Share Document