Determination of minimum inhibitory concentrations of itraconazole, terbinafine and ketoconazole against dermatophyte species by broth microdilution method

Correlation of plasma levels of itraconazole with treatment response at 4 weeks in chronic dermatophytosis: Results of a randomised controlled trial

BACKGROUND

Itraconazole in varying doses and duration is being frequently used for the management of dermatophytosis. There is a scarcity of studies on the bioavailability of various itraconazole brands available in the market.

AIMS AND OBJECTIVES

The aim of this study was to determine the plasma concentration of itraconazole of various brands and its correlation with clinical efficacy in chronic dermatophytosis.

MATERIALS AND METHODS

One hundred patients with chronic dermatophytosis with age >18 years were studied at the outpatient clinic of our tertiary care hospital. Plasma itraconazole level was estimated on Week 2 and Week 4 after randomly dividing the patients into Groups A, B and C who received cap itraconazole 100 mg twice a day of innovator, multinational and local generic brands, respectively, for 4 weeks. Both efficacy (cure, partial cure or no cure), safety and recurrence were compared between the three groups.

RESULTS

At 4 weeks, number of patients classified as 'cured' were 10/26 (38.4%) in Group A, 5/22 in Group B (22.7%) and 3/21 (14.2%) in Group C (p = .002). Mycological cure rates at Week 4 in Groups A, B and C were 21 (80.8%), 17 (81.0%) and 5 (26.3%), respectively (p = .006). Plasma levels of itraconazole were comparable between the three groups at Week 2 and Week 4. No statistically significant correlation was found between itraconazole levels and treatment response in any of the groups at 4 weeks. Incidence of adverse effects and recurrence rates was also similar among the three groups.

CONCLUSION

Cure rates for chronic dermatophytosis were poor with all three itraconazole brands at 4 weeks of treatment. Higher cure rates were obtained with innovator drug as compared to multinational and local generic brands at 4 weeks. Plasma levels of the three drugs were however similar, indicating that factors other than serum bioavailability are at play in determining response of chronic dermatophyte infections to oral itraconazole.

Species Distribution and Antifungal Susceptibility Profile of Dermatophytes from a Tertiary Care Centre in North India

Objective Dermatophytoses, one of the most ancient diseases, is becoming a menace in recent times. This has made the knowledge of antifungal susceptibility a priority in today's times.

Material and Methods This is a prospective study conducted over 18 months including all dermatophytes isolated during the period. Dermatophytes were identified by routine phenotypic methods. Antifungal susceptibility testing was performed for griseofulvin, terbinafine, and itraconazole as per the Clinical Laboratory Standard Institute M38 A2, and minimum inhibitory concentrations (MICs) were read after 5 days.

Results Patient details and associated risk factors were recorded. Fixed dose combinations with steroids were associated with 79.3% (46 out of 58) of patients with dermatophytosis of skin. Among the 72 dermatophytes isolated during the study period, 58 (80.5%) were isolated from skin scrapings and 14 (19.4%) from nail samples. Tinea corporis with cruris was the most common presentation. The most common dermatophyte isolated from skin scrapings was Trichophyton mentagrophytes complex (70.6%, 41 out of 58), while from nail samples it was Trichophyton rubrum complex (78.57%, 11 out of 14). Based on the MIC50 and MIC90 results, itraconazole showed the lowest MICs, followed by terbinafine and then griseofulvin.

Conclusion With the changing epidemiology of species distribution and antifungal resistance, there is a need for continuous surveillance of these parameters of dermatophytes.

Phylogeny, Antifungal Susceptibility, and Point Mutations of SQLE Gene in Major Pathogenic Dermatophytes Isolated From Clinical Dermatophytosis

Drug resistance is one of the major challenges to skin fungal infections, especially in tropical and subtropical infections caused by dermatophytes. This study aimed to determine the antifungal susceptibility of clinically dermatophytes and evaluate point mutations in terbinafine-resistant isolates. A total number of 123 clinical dermatophyte isolates in eight species were evaluated in terms of sensitivity to seven major antifungals. Furthermore, the point mutation in squalene epoxidase (SQLE) gene responsible for terbinafine resistance was studied. The dermatophytes species were identified by morphological characteristics and confirmed by the ITS sequencing. Also, the phylogenetic tree was drawn using the RAxML analyses for 123 dermatophytes isolates. A new XXIX genotype was also found in 4 Trichophyton mentagrophytes isolates. Based on the results obtained, terbinafine was the most effective antifungal drug followed by itraconazole and voriconazole. Trichophyton rubrum and Trichophyton tonsurans were the most susceptible species (MIC₅₀ = 0.01, 0.09 μg/ml), and T. mentagrophytes was the most resistant species (MIC₅₀ = 0.125 μg/ml) to terbinafine. Of the 123 dermatophytes isolates, six isolates showed reduced susceptibility to terbinafine, and only Trichophyton indotineae had a mutation in SQLE gene as a Phe397Leu substitution. Overall, the antifungal susceptibility test is necessary for managing dermatophytosis. These results help physicians to control the course of the disease and provide further insights to select effective drugs for patients with dermatophytosis, especially in tropical and subtropical regions of the world, where dermatophytosis is still a public health problem.

Terbinafine Resistant Trichophyton Indotineae Isolated in Patients with Superficial Dermatophyte Infection in Canadian Patients

BACKGROUND

Trichophyton mentagrophytes type VIII (segregated as Trichophyton indotineae) is a new strain of antifungal resistant Trichophyton spp. that has been found in different countries around the world. This new strain has been found to be resistant to terbinafine.

OBJECTIVES

We present the clinical characteristics, diagnosis and treatment approach of Canadian patients with mycology and molecular confirmation of superficial mycosis caused by T. indotineae.

METHODS

Mycology testing from cultures and PCR were used to confirm T. indotineae. We collected clinical information from patients with a confirmed diagnosis.

RESULTS

We report eight Canadian patients mainly presenting with extensive superficial mycosis due to T. indotineae. Three patients presented lesions on the face in addition to lesions on their body. Four patients were initially started on itraconazole or fluconazole, one patient was started on topical therapy, and three patients were referred to infectious disease.

CONCLUSIONS

This new strain represents a dermatology and public health concern. Treatment guidelines are lacking. We include a practical approach and treatment recommendations for clinicians who will be encountering these emerging cases in Canada while waiting for evidence-based treatment guidelines.

Dermatophytic infection and in vitro activities of antifungal drugs against dermatophytes in rural India

Background Increase in resistance to conventional antifungals renders the need for antifungal sensitivity testing in Dermatophytes.   The present study aimed at determining the prevalence of dermatophytic infections and their susceptibility pattern in a rural healthcare facility. Methods Patients with suspected dermatophytosis attending the dermatology outpatient department were enrolled in the study. Specimen collection for mycological examinations was done. In-vitro antifungal sensitivity testing was performed as per the Clinical and Laboratory Standard Institute (CLSI) M38-A2 (2008) standards with broth microdilution method. Results Onychomycosis was the commonest (41.9%) presentation. Dermatophytic prevalence based on culture was 110 (70.9%). The commonest species was Trichophyton rubrum (36.8%). Terbinafine was found to be the most effective drug, followed by ketoconazole and itraconazole. Conclusion Antifungal sensitivity in dermatophytic infections should be made a routine in tertiary healthcare facilities as we are already witnessing the rampage of emerging fungal infection– Mucormycosis in the nation and worldwide.

Chronic Dermatophytosis: Clinico-Mycological Determinants and Antifungal Susceptibility Pattern

Background:

Recent years have witnessed a dramatic increase in chronic unresponsive dermatophytosis. A study was conducted to quantify the proportion of patients with chronic dermatophytosis and to determine the clinico-mycological predictors of chronicity including antifungal susceptibility.

Methods:

Hospital-based cross-sectional study design was adopted. Four hundred and twenty-five patients were studied. The outcome variable was chronic dermatophytosis and the determinants were clinico-mycological characteristics. Chi-square and odds ratio (OR) with 95% confidence interval (CI) were calculated.

Results:

Chronic dermatophytosis was seen in 29.4%. Past history of dermatophytosis, OR 0.44 (95% CI 0.28–0.68); family history of dermatophytosis, OR 1.66 (95% CI 1.06–2.56); HIV infection, OR 9.88 (95% CI 1.09–89.33); treatment with topical antifungals, OR 2.4 (95% CI 1.5–3.9); systemic antifungals, OR 3.9 (95% CI 2.5–6.1); topical steroids, OR 2.02 (95% CI 1.25–3.25); multiple-site infection, OR 1.97 (95% CI 1.24–3.13); and tinea unguium, OR 6.52 (95% CI 2.89–14.7) were the significant determinants. Trichophyton mentagrophytes (73.6%) was the most common isolate followed by Trichophyton rubrum and Microsporum gypseum (13.2%) each. A percentage of 77.4 of the isolates were resistant—73.6% isolates to terbinafine and 3.8% isolates to fluconazole. None of the isolates were resistant to itraconazole.

Conclusion:

Significant determinants were host-related factors. Thorough history taking, patient examination, and education can improve the present scenario. Microbiological resistance was not a significant predictor. High proportion of resistant strains should be an eye opener. Developing and adopting a standard uniform treatment protocol throughout the country should be the need of the hour.

Molecular Epidemiology and Antifungal Susceptibility of Trichophyton Isolates in Greece: Emergence of Terbinafine-Resistant Trichophytonmentagrophytes Type VIII Locally and Globally

Trichophyton isolates with reduced susceptibility to antifungals are now increasingly reported worldwide. We therefore studied the molecular epidemiology and the in vitro antifungal susceptibility patterns of Greek Trichophyton isolates over the last 10 years with the newly released EUCAST reference method for dermatophytes. Literature was reviewed to assess the global burden of antifungal resistance in Trichophyton spp. The in vitro susceptibility of 112 Trichophyton spp. molecularly identified clinical isolates (70 T. rubrum, 24 T. mentagrophytes, 12 T. interdigitale and 6 T. tonsurans) was tested against terbinafine, itraconazole, voriconazole and amorolfine (EUCAST E.DEF 11.0). Isolates were genotyped based on the internal transcribed spacer (ITS) sequences and the target gene squalene epoxidase (SQLE) was sequenced for isolates with reduced susceptibility to terbinafine. All T. rubrum, T. interdigitale and T. tonsurans isolates were classified as wild-type (WT) to all antifungals, whereas 9/24 (37.5%) T. mentagrophytes strains displayed elevated terbinafine MICs (0.25–8 mg/L) but not to azoles and amorolfine. All T. interdigitale isolates belonged to ITS Type II, while T. mentagrophytes isolates belonged to ITS Type III* (n = 11), VIII (n = 9) and VII (n = 4). All non-WT T. mentagrophytes isolates belonged to Indian Genotype VIII and harbored Leu393Ser (n = 5) and Phe397Leu (n = 4) SQLE mutations. Terbinafine resistance rates ranged globally from 0–44% for T. rubrum and 0–76% for T. interdigitale/T. mentagrophytes with strong endemicity. High incidence (37.5%) of terbinafine non-WT T. mentagrophytes isolates (all belonging to ITS Type VIII) without cross-resistance to other antifungals was found for the first time in Greece. This finding must alarm for susceptibility testing of dermatophytes at a local scale particularly in non-responding dermatophytoses.

Mechanism of streptomyces albidoflavus STV1572a derived 1-heneicosanol as an inhibitor against squalene epoxidase of Trichophyton mentagrophytes

An increase in incidences of tinea infections paves the way to discover the novel antifungal drugs from unexplored natural resources. The quality of life in patients with tinea infection may be affected by different factors, including morbidity, length of illness, social and demographic factors. The present investigation explores the functional principle of a bioactive compound isolated from actinomycetes, S. albidoflavus STV1572a by in-silico and in-vitro studies. In continuation of our previous reports on the antidermatophytic potential of S. albidoflavus STV1572a, this study progresses with the in-silico molecular docking study of the seven GC-MS discovered ligands, and six dermatophytic modelled targets. Through virtual screening, it was revealed that a docking score -8.8 between 1-heneicosanol and squalene epoxidase favored partially in understanding the mode of action. Further validation of in-silico study was performed by a sterol quantification assay which confirmed the antidermatophytic mechanism of 1-heneicosanol. Taken together, the evidence from this study suggests that 1-heneicosanol has a potential antidermatophytic compound and can be considered for dermatophytic treatment.

Evaluation of susceptibility and response in the surface of agents of surface mycoses (Trichophyton mentagrophytes; T. tonsurans) to antifungal drugs of interest in a medical clinic

Introduction: The resistance of fungal species to drugs usually used in clinics is of great interest in the medical field. Objective: To evaluate susceptibility and in vitro response of species of Trichophyton spp. to antifungal drugs of interest in clinical medicine. Methods: 12 samples of clinical isolates from humans were used, nine of T. mentagrophytes and three of T. tonsurans. Susceptibility tests were performed according to the agar diffusion (AD) and broth microdilution (BM) methods. Results: In the AD method, the species T. tonsurans presented a percentage of sensitivity of 33% in relation to amphotericin B and 66% to itraconazole, with 100% resistance to ketoconazole and fluconazole. T. mentagrophytes also showed 100% resistance to ketoconazole in this technique, with 11% sensitivity to ketoconazole, 22% to itraconazole and 22% of samples classified as sensitive dose dependent. In the MC method, the species T. tonsurans presented a sensitivity percentage of 66%, 55% and 33% in relation to ketoconazole, fluconazole and itraconazole, respectively. The T. mentagrophytes species presented sensitivity percentages of 11%, 11%, 33% and 55% for amphotericin B, itraconazole, ketoconazole and fluconazole, respectively. Conclusion: There was resistance in vitro of the species of T. mentagrophytes and T. tonsurans against the antifungal fluconazole and relative resistance against ketoconazole in the AD method. In BM, however, important percentages of sensitivity were observed for the two species analyzed in relation to the antifungals fluconazole and ketoconazole when compared to itraconazole and amphotericin B.

Regional Differences in Antifungal Susceptibility of the Prevalent Dermatophyte Trichophyton rubrum

In vitro susceptibility testing for Trichophyton rubrum has shown resistance to terbinafine, azoles and amorolfine, locally, but epidemiological cutoffs are not available. In order to assess the appropriateness of current first-line antifungal treatment for T. rubrum in China, we characterized antifungal susceptibility patterns of Chinese T. rubrum strains to nine antifungals and also described the upper limits of wild-type (WT) minimal inhibitory concentrations (MIC) (UL-WT) based on our study and another six studies published during the last decades. Sixty-two clinical isolates originating from seven provinces in China were identified as T. rubrum sensu stricto; all Chinese strains showed low MICs to eight out of nine antifungal drugs. Terbinafine (TBF) showed the lowest MICs of all antifungal classes tested in both the Chinese and global groups, with a 97.5% UL-WT MIC-value of 0.03 mg/L. No non-WT isolates were observed for TBF in China, but were reported in 18.5% of the global group. Our study indicated that TBF was still the most active drug for Chinese T. rubrum isolates, and all strains were within the WT-population. TBF therefore remains recommended for primary therapy to dermatophytosis caused by T. rubrum in China now, but regular surveillance of dermatophytes and antifungal susceptibility is recommended.

Intrinsic resistance to terbinafine among human and animal isolates of Trichophyton mentagrophytes related to amino acid substitution in the squalene epoxidase

BACKGROUND

Dermatomycoses are the most common fungal infections in the world affecting a significant part of the human and animal population. The majority of zoophilic infections in humans are caused by Trichophyton mentagrophytes. Currently, the first-line drug for both oral and topical therapy is terbinafine. However, an increasing number of cases that are difficult to be cured with this drug have been noted in Europe and Asia. Resistance to terbinafine and other allylamines is very rare and usually correlated with point mutations in the squalene epoxidase gene resulting in single amino acid substitutions in the enzyme, which is crucial in the ergosterol synthesis pathway.

PURPOSE

Here, we report terbinafine-resistant T. mentagrophytes isolates among which one was an etiological factor of tinea capitis in a man and three were obtained from asymptomatic foxes in Poland.

METHODS

We used the CLSI protocol to determine antifungal susceptibility profiles of naftifine, amphotericin B, griseofulvin, ketoconazole, miconazole, itraconazole, voriconazole, and ciclopirox. Moreover, the squalene epoxidase gene of the terbinafine-resistant strains was sequenced and analysed.

RESULTS

In the genomes of all four resistant strains exhibiting elevated MICs to terbinafine (16 to 32 µg/ml), single-point mutations leading to Leu393Phe substitution in the squalene epoxidase enzyme were revealed. Among the other tested substances, a MIC50 value of 1 µg/ml was shown only for griseofulvin.

CONCLUSION

Finally, our study revealed that the terbinafine resistance phenomenon might not be acquired by exposure to the drug but can be intrinsic. This is evidenced by the description of the terbinafine-resistant strains isolated from the asymptomatic animals.

Population differentiation, antifungal susceptibility, and host range of Trichophyton mentagrophytes isolates causing recalcitrant infections in humans and animals

The major problems in determining the causative factors of the high prevalence of dermatophytoses include the lack of a well-standardized antifungal susceptibility testing method, the low consistency of in vitro and clinical minimal inhibitory concentration values, the high genomic diversity of the population, and the unclear mechanism of pathogenicity. These factors are of particular importance when the disease is recalcitrant and relapses. Herein, we identified and characterized Trichophyton mentagrophytes isolates obtained from therapy-resistant cases in humans and animals. We used genomic diversity analysis of 17 human and 27 animal clinical isolates with the MP-PCR technique, determined their phenotypic enzymatic activity and host range, and performed antifungal susceptibility testing to currently available antifungal drugs from various chemical groups. Genomic diversity values of 35.3% and 33.3% were obtained for clinical isolates from humans and animals, respectively, yet without any relationship to the host species or antifungal drug to which resistance in therapy was revealed. The highest activity of keratinase enzymes was recorded for fox, guinea pig, and human hairs. These hosts can be considered as the main species in the host range of these isolates. A phenyl morpholine derivative, i.e. amorolfine, exhibited superior activity against strains obtained from both humans and animals with the lowest MIC₅₀. Interestingly, high compliance of terbinafine in vitro resistance with clinical problems in the treatment with this substance was shown as well. The high resistance of dermatophytes to drugs is the main cause of the recalcitrance of the infection, whereas the other features of the fungus are less important.

MIC and Upper Limit of Wild-Type Distribution for 13 Antifungal Agents against a Trichophyton mentagrophytes-Trichophyton interdigitale Complex of Indian Origin

Dermatophytosis due to the Trichophyton mentagrophytes-Trichophyton interdigitale complex is being increasingly reported across India. Reports of therapeutic failure have surfaced recently, but there are no clinical break points (CBP) or epidemiological cutoffs (ECVs) available to guide the treatment of dermatophytosis. In this study, a total of 498 isolates of the T. mentagrophytes -interdigitale complex were collected from six medical centers over a period of five years (2014 to 2018). Antifungal susceptibility testing of the isolates was carried out for itraconazole, fluconazole, ketoconazole, voriconazole, luliconazole, sertaconazole, miconazole, clotrimazole, terbinafine, amorolfine, naftifine, ciclopirox olamine, and griseofulvin. The MICs (in mg/liter) comprising >95% of the modeled populations were as follows: 0.06 for miconazole, luliconazole, and amorolfine; 0.25 for voriconazole; 0.5 for itraconazole, ketoconazole, and ciclopirox olamine; 1 for clotrimazole and sertaconazole; 8 for terbinafine; 16 for naftifine; 32 for fluconazole; and 64 for griseofulvin. A high percentage of isolates above the upper limit of the wild-type MIC (UL-WT) were observed for miconazole (29%), luliconazole (13.9%), terbinafine (11.4%), naftifine (5.2%), and voriconazole (4.8%), while they were low for itraconazole (0.2%). Since the MICs of itraconazole were low against the T. mentagrophytes -interdigitale complex, this could be considered the choice of first-line treatment. The F397L mutation in the squalene epoxidase (SE) gene was observed in 77.1% of isolates with a terbinafine MIC of ≥1 mg/liter, but no mutation was detected in isolates with a terbinafine MIC of <1 mg/liter. In the absence of CBPs, evaluation of the UL-WT may be beneficial for managing dermatophytosis and monitoring the emergence of isolates with reduced susceptibility.

In Vitro Ravuconazole Susceptibility of Anthropophilic Dermatophyte Strains Isolated from Japanese Patients

Ravuconazole (RVCZ) is a new human anti-fungal azole drug available in Japan since 2018 and is a broad-spectrum agent that exhibits excellent activity against dermatophytes. In the present study, the in vitro RVCZ susceptibility of clinical isolates of anthropophilic dermatophytes, including Trichophyton interdigitale strains with either low susceptibility to itraconazole (ITCZ) or resistance to terbinafine (TEBR), was investigated using the Clinical & Laboratory Standards Institute M38-A2 test. The MICs of RCVZ for 20 clinical isolates of T. interdigitale were < 0.03125-0.125 mg/L; for 4 clinical isolates of T. rubrum, < 0.03125-0.0625 mg/L; and for 20 clinical isolates of T. tonsurans, < 0.03125 mg/L. Similarly, the MICs of RCVZ for the T. interdigitale strains with either low susceptibility to ITCZ or resistance to TEBR were also < 0.03125 mg/L. To our knowledge, this is first study to investigate the in vitro RVCZ susceptibility of T. interdigitale strains with either low susceptibility to ITCZ or resistance to TEBR. Our results indicated that RVCZ was the most effective drug against these strains.

Comparison of in vitro activities of 11 antifungal agents against Trichophyton verrucosum isolates associated with a variety hosts and geographical origin

The high prevalence of dermatophytosis in animals is usually associated with extra expenditure on prevention, diagnosis and long-term treatment. Humans are usually infected from animals, also from asymptomatic carriers, through direct contact or indirectly via fungus-bearing hair, scales and fomites. Despite the medical importance of Trichophyton verrucosum infections, there are limited in vitro data on the fungal susceptibility to antifungal drugs, including new-generation triazoles, imidazoles and allyloamines. The aim of the current study was to evaluate comprehensively the in vitro activity of 11 antifungal drugs against a large collection of T. verrucosum isolates obtained in Poland, Latvia, Lithuania and Slovakia from humans and animals using a microdilution assay. In vitro susceptibility testing of 11 antifungal drugs was performed according to the Clinical and Laboratory Standards Institute (CLSI) document M38. The MICs of clotrimazole, ciclopirox, enilconazole, miconazole, naftifine and terbinafine against all T. verrucosum isolates were below 1 μg/mL, whereas those of fluconazole, griseofulvin, itraconazole, ketoconazole and voriconazole were above 1 μg/mL. Ciclopirox was demonstrated to have superior activity against all strains in comparison with the other drugs, whereas fluconazole exerted the weakest in vitro effect and exhibited the highest MIC values. Our study has shown that drugs of different chemical origin have satisfactory antifungal activity and can be promising candidates for the treatment of T. verrucosum dermatophytosis. Moreover, no significant disparity in drug sensitivity between isolates obtained from different hosts and geographical regions have been demonstrated.

Production of anti-Trichophyton rubrum egg yolk immunoglobulin and its therapeutic potential for treating dermatophytosis

The aim of this study was to estimate the therapeutic potential of specific egg yolk immunoglobulin (IgY) on dermatophytosis caused by Trichophyton rubrum. The IgY was produced by immunizing hens with cell wall proteins of T. rubrum, extracted from eggs by PEG precipitation and then purified by ammonium sulfate precipitation. The cross-reactivity (CR) with other fungi, growth inhibition on T. rubrum in vitro and therapeutic effect on T. rubrum infection in BALB/C mice of the specific IgY were then evaluated. Anti- T. rubrum cell wall proteins IgY (anti-trCWP IgY) presented a certain degree of cross-reactivity with different fungi. In the in vitro and in vivo activity researches, Anti-trCWP IgY showed a significant dose-dependent growth inhibitory effect on T. rubrum in vitro and a significant dose-dependent therapeutic effect on T. rubrum infection in BALB/C mice.

Determination of antifungal minimum inhibitory concentration and its clinical correlation among treatment failure cases of dermatophytosis

Introduction:

Dermatophytes are most common infectious agents causing superficial mycosis worldwide. A number of topical as well as systemic antifungal drugs are available for treatment of dermatophytosis. Superficial mycosis caused by dermatophytes can be easily treated by topical or oral antifungal drugs, but in the course of time, an increased number of treatment failure cases are appearing. Possible cause for treatment failure could be poor patient compliance, poor drug penetration into affected lesion, and also drug resistance in dermatophytes. The aim of this study is to investigate minimum inhibitory concentration and clinical correlation in treatment failure cases of dermatophytosis.

Methods:

Skin, hair and nail samples were collected from treatment failure cases of dermatophytosis. A total 75 isolates were tested for MIC against four antifungal drugs in the study. Fluconazole, itraconazole, ketoconazole and terbinafine were the antifungal drugs tested using broth microdilution method. MIC₅₀ and MIC₉₀ values were recorded.

Results:

A total of 75 dermatophytic isolates were tested. Dermatophytic isolates in this study were Trichophyton mentagrophytes (n = 31), T. rubrum (n = 13), T. tonsurans (n = 12), T. verrucosum (n = 9), M. gypseum (n = 5), E. floccosum (n = 4) and T. violaceum (n = 1). MIC₉₀ value for fluconazole and terbinafine was significantly higher.

Conclusion:

MIC of 17.33% isolates for fluconazole and 33.33% isolates for terbinafine were lower than cut-off value, which indicates that not all treatment failure cases are due to drug resistance.

In Vitro Activity of Antifungal Drugs Against Trichophyton rubrum and Trichophyton mentagrophytes spp. by E-Test Method and Non-supplemented Mueller-Hinton Agar Plates

Trichophyton rubrum and Trichophyton mentagrophytes spp. are two of the most frequently isolated dermatophytes causing dermatophytosis worldwide. Since the incidence of resistance to antifungal agents is increasing, antifungal susceptibility tests are needed to successfully treat dermatophytoses. Most of the methods currently available are complicated, time-consuming and lack of reference procedures. The aim of this work was to establish a simple protocol to test the susceptibility of dermatophytes isolated from clinical samples against five antifungal drugs using E-test and disk diffusion methods. We used the E-test on non-supplemented Mueller-Hinton agar plates to determine the minimum inhibitory concentrations (MICs) of fluconazole, itraconazole, voriconazole and amphotericin B, and disk diffusion method to determine the interpretive MIC of terbinafine. Fifty dermatophytes-10 T. rubrum and 40 T. mentagrophytes spp.-were assessed after only 96 h of colony growth. Terbinafine was the most active antifungal agent with an inhibition diameter greater than 70 mm (sensitivity > 20 mm), followed by voriconazole, itraconazole and amphotericin B with MICs ranging from 0.032 to 0.38 µg/mL, from 0.006 to 0.125 µg/mL and from 0.5 to 1.5 µg/mL, respectively. All isolates were resistant to fluconazole. Collectively, the less laborious E-test and disk diffusion method were shown to be suitable and reliable to determine antifungal sensitivity of dermatophytes. This simple standard protocol could be employed in the routine of clinical laboratories.

A prospective study of the epidemiological and clinical patterns of recurrent dermatophytosis at a tertiary care hospital in India

Background

Recurrent and clinically unresponsive dermatophytosis is being increasingly encountered in our country. It runs a protracted course with exacerbations and remissions. However, there is little information regarding the extent of the problem and the characteristics of recurrent dermatophytosis in published literature.

Aims

We sought to determine the prevalence, risk factors and clinical patterns of recurrent dermatophytosis in our institution. We also investigated the causative dermatophyte species and antifungal susceptibility patterns in these species.

Methods

One hundred and fifty patients with recurrent dermatophytosis attending the outpatient department of the Postgraduate Institute of Medical Education and Research, Chandigarh, India were enrolled in the study conducted from January 2015 to December 2015. A detailed history was obtained in all patients, who were then subjected to a clinical examination and investigations including a wet preparation for direct microscopic examination, fungal culture and antifungal susceptibility tests.

Results

Recurrent dermatophytosis was seen in 9.3% of all patients with dermatophytosis in our study. Trichophyton mentagrophytes was the most common species identified (36 patients, 40%) samples followed by T. rubrum (29 patients, 32.2%). In-vitro antifungal susceptibility testing showed that the range of minimum inhibitory concentrations (MIC) on was lowest for itraconazole (0.015-1), followed by terbinafine (0.015-16), fluconazole (0.03-32) and griseofulvin (0.5-128) in increasing order.

Limitation

A limitation of this study was the absence of a suitable control group (eg. patients with first episode of typical tinea).

Conclusion

Recurrence of dermatophytosis was not explainable on the basis of a high (MIC) alone. Misuse of topical corticosteroids, a high number of familial contacts, poor compliance to treatment over periods of years, and various host factors, seem to have all contributed to this outbreak of dermatophytosis in India.

Tinea Pseudoimbricata as a Unique Manifestation of Steroid Abuse: A Clinico-Mycological and Dermoscopic Study from a Tertiary Care Hospital

Background:

Tinea pseudoimbricata, characterized by concentric scaly rings simulating Tinea imbricata is caused by dermatophytes other than Trichophyton concentricum. It is reported to occur in patients with steroid abuse and in immunocompromised individuals.

Aim:

To study the clinico-mycological profile and dermoscopic features of T. pseudoimbricata in immunocompetent patients.

Methods:

We have evaluated 14 consecutive, clinically diagnosed patients of T. pseudoimbricata with positive 10% potassium hydroxide (KOH) examination and culture, seen over a period of 6 months. Dermoscopy was performed in all patients. The demographic, clinical, and mycological features of each patient were recorded on a predesigned proforma.

Results:

There were seven male and seven female patients with a mean age of 27.6 years and a mean disease duration of 3.8 months. All patients gave a history of application of potent or super-potent topical steroid with or without oral/injectable steroid for varying duration. Culture isolates were Trichophyton mentagrophytes complex and Trichophyton rubrum in 11 and 3 patients, respectively. Dermoscopic analysis showed features of steroid abuse in majority of the patients.

Limitation:

A small sample size was the limitation of our study.

Conclusion:

T. pseudoimbricata is a special subset of Tinea incognito caused by injudicious and inappropriate use of topical steroid. The typical appearance should alert the dermatologists regarding the possible abuse of steroids. Most common species isolated on culture was T. mentagrophytes complex.

A Study of In vitro Antifungal Susceptibility Patterns of Dermatophytic Fungi at a Tertiary Care Center in Western India

Background:

Recent years have seen an alarming rise in the prevalence of recalcitrant and relapsing dermatophyte infections in India associated with lack of clinical response to standard antifungal regimens.

Aims and Objectives:

A study was undertaken to identify the antifungal susceptibility patterns of dermatophyte species isolated from lesions of dermatophytoses in patients examined at our center.

Materials and Methods:

A total of 85 patients with clinically diagnosed dermatophytoses were subjected to skin scrapings for potassium hydroxide mount (microscopic examination) and culture using Sabouraud's agar medium containing chloramphenicol and cycloheximide (incubated at 30°C). Antifungal susceptibilities [minimum inhibitory concentration-90 (MIC-90)] of the identified dermatophytes were tested for seven systemic and topical antifungal agents (terbinafine, griseofulvin, itraconazole, fluconazole, sertaconazole, ketoconazole, and clotrimazole) using Clinical and Laboratory Standards Institute broth microdilution method (M38-A).

Results:

Trichophyton rubrum (50%) and Trichophyton mentagrophytes complex (47.2%) were the two major species isolated. Isolates of both showed downy and granular forms (61.11%, 38.89% and 32.35%, 67.65%, respectively). The overall in-vitro susceptibility profiles (MIC-90 ranges in μg/mL) of the seven drugs for T. rubrum and T. mentagrophytes complex respectively were as follows: terbinafine (0.008–0256, 0.016–0.256), griseofulvin (0.03-1, 0.06–1), itraconazole (0.125-2, 0.25–2), fluconazole (0.125–1, 0.25–32), sertaconazole (0.03-1, 0.03-1), ketoconazole (0.06–1, 0.125–1), and clotrimazole (0.03–2, 0.06–1).

Conclusions:

This study indicates a rising proportion of T. mentagrophytes complex with increased proportion of granular form (T. mentagrophytes var. mentagrophytes). This study represents the current antifungal susceptibility profile of dermatophytic infections in a tertiary care medical center in western India with rising MICs to terbinafine and itraconazole.

Therapy and Antifungal Susceptibility Profile of Microsporum canis

Microsporum canis is a worldwide diffused zoophilic dermatophyte which causes clinical conditions often characterised by multifocal alopecia, scaling, and circular lesions in many animal species, including humans. A large variety of oral and topical antifungal protocols is available for treating M. canis infection. However, the efficacy of these drugs and treatment protocols is variable, with treatment failure up to 40% of patients possibly due to resistance phenomena. The lack of standardised reference methods for evaluating the antifungal susceptibility of M. canis represents a major hindrance in assessing microbiological resistance in unresponsive clinical cases. Therefore, data about conventional therapy against M. canis and the protocols employed to test the antifungal activity of the most commonly employed drugs (i.e., azoles, polyenes, allylamines, and griseofulvin) have been summarised herein. This article focuses on technical parameters used for antifungal susceptibility tests, their effects on the minimum inhibitory concentration value, as well as their clinical implications.

Molecular Identification and Antifungal Susceptibility Patterns of Clinical Dermatophytes Following CLSI and EUCAST Guidelines

Dermatophytes are associated with superficial infections in humans worldwide. The aim of the present study was to determine the species distribution and susceptibility patterns of clinical dermatophytes. Samples received for routine mycological processing from 124 suspected cases attending a dermatologic clinic in a tertiary care hospital were included in the study. On direct microscopy, 74.1% (92/124) were positive and 53.2% (66/124) grew on culture. The isolates were comprised of Trichophytoninterdigitale (56%) followed by Trichophytontonsurans (25.7%), Trichophytonrubrum (7.5%), Trichophytonviolaceum (4.5%), Microsporumgypseum (4.5%), and Trichophytonverrucosum (1.5%). Conventional mycological identification was concordant with ITS sequencing except for T.mentagrophytes. High minimum inhibitory concentration (MIC) values (geometric mean, >1 µg/mL) were observed for T.tonsurans and T.rubrum to terbinafine and griseofulvin. This study highlights the shift in epidemiology from T.rubrum to T.interdigitale. It also raises a concern of high MICs of terbinafine and griseofulvin among our isolates. Surveillance of antifungal susceptibility patterns can provide clinicians with local MIC data that can further aid in guiding better management in relapse cases of dermatomycosis.