An evaluation of the in vitro activity of terbinafine

Sources of Antifungal Drugs

Due to their eukaryotic heritage, the differences between a fungal pathogen's molecular makeup and its human host are small. Therefore, the discovery and subsequent development of novel antifungal drugs are extremely challenging. Nevertheless, since the 1940s, researchers have successfully uncovered potent candidates from natural or synthetic sources. Analogs and novel formulations of these drugs enhanced the pharmacological parameters and improved overall drug efficiency. These compounds ultimately became the founding members of novel drug classes and were successfully applied in clinical settings, offering valuable and efficient treatment of mycosis for decades. Currently, only five different antifungal drug classes exist, all characterized by a unique mode of action; these are polyenes, pyrimidine analogs, azoles, allylamines, and echinocandins. The latter, being the latest addition to the antifungal armamentarium, was introduced over two decades ago. As a result of this limited arsenal, antifungal resistance development has exponentially increased and, with it, a growing healthcare crisis. In this review, we discuss the original sources of antifungal compounds, either natural or synthetic. Additionally, we summarize the existing drug classes, potential novel candidates in the clinical pipeline, and emerging non-traditional treatment options.

Metagenomics of Toenail Onychomycosis in Three Victorian Regions of Australia

Onychomycosis is a fungal disease of the nail that is found worldwide and is difficult to diagnose accurately. This study used metagenomics to investigate the microbiology of 18 clinically diagnosed mycotic nails and two normal nails for fungi and bacteria using the ITS2 and 16S loci. Four mycotic nails were from Bass Coast, six from Melbourne Metropolitan and eight from Shepparton, Victoria, Australia. The mycotic nails were photographed and metagenomically analysed. The ITS2 sequences for T. rubrum and T. interdigitale/mentagrophytes averaged over 90% of hits in 14/18 nails. The high abundance of sequences of a single dermatophyte, compared to all other fungi in a single nail, made it the most likely infecting agents (MLIA). Trichophyton rubrum and T. interdigitale/mentagrophytes were found in Bass Coast and Shepparton while only T. interdigitale/mentagrophytes was found in Melbourne. Two nails with T. interdigitale/mentagrophytes mixed with high abundance non-dermatophyte moulds (NDMs) (Aspergillus versicolor, Acremonium sclerotigenum) were also observed. The two control nails contained chiefly Fusarium oxysporum and Malassezia slooffiae. For bacteria, Staphylococcus epidermidis was in every nail and was the most abundant, including the control nails, with an overall mean rate of 66.01%. Rothia koreensis, Corynebacterium tuberculostearicum, and Brevibacterium sediminis also featured.

Preparation of Terbinafin-Encapsulated Solid Lipid Nanoparticles Containing Antifungal Carbopol® Hydrogel with Improved Efficacy: In Vitro, Ex Vivo and In Vivo Study

The present research was aimed to develop a terbinafin hydrochloride (TH)-encapsulated solid lipid nanoparticles (SLNs) hydrogel for improved antifungal efficacy. TH-loaded SLNs were obtained from glyceryl monostearate (lipid) and Pluronic® F68 (surfactant) employing high-pressure homogenization. The ratio of drug with respect to lipid was optimized, considering factors such as desired particle size and highest percent encapsulation efficiency. Lyophilized SLNs were then incorporated in the hydrogel prepared from 0.2–1.0% w/v carbopol 934P and further evaluated for rheological parameters. The z-average, zeta potential and polydispersity index were found to be 241.3 nm, −15.2 mV and 0.415, respectively. The SLNs show a higher entrapment efficiency of about 98.36%, with 2.12 to 6.3602% drug loading. SEM images, XRD and the results of the DSC, FTIR show successful preparation of SLNs after freeze drying. The TH-loaded SLNs hydrogel showed sustained drug release (95.47 ± 1.45%) over a period of 24 h. The results reported in this study show a significant effect on the zone of inhibition than the marketed formulation and pure drug in Candida albicans cultures, with better physical stability at cooler temperatures. It helped to enhance skin deposition inthe ex vivostudy and improved, in vitro and in vivo, the antifungal activity.

Efficacy of antifungal agents against fungal spores: An in vitro study using microplate laser nephelometry and an artificially infected 3D skin model

Dermal fungal infections seem to have increased over recent years. There is further a shift from anthropophilic dermatophytes to a growing prevalence of zoophilic species and the emergence of resistant strains. New antifungals are needed to combat these fungi and their resting spores. This study aimed to investigate the sporicidal effects of sertaconazole nitrate using microplate laser nephelometry against the microconidia of Trichophyton, chlamydospores of Epidermophyton, blastospores of Candida, and conidia of the mold Scopulariopsis brevicaulis. The results obtained were compared with those from ciclopirox olamine and terbinafine. The sporicidal activity was further determined using infected three-dimensional full skin models to determine the antifungal effects in the presence of human cells. Sertaconazole nitrate inhibited the growth of dermatophytes, molds, and yeasts. Ciclopirox olamine also had good antifungal activity, although higher concentrations were needed compared to sertaconazole nitrate. Terbinafine was highly effective against most dermatophytes, but higher concentrations were required to kill the resistant strain Trichophyton indotineae. Sertaconazole nitrate, ciclopirox olamine, and terbinafine had no negative effects on full skin models. Sertaconazole nitrate reduced the growth of fungal and yeast spores over 72 h. Ciclopirox olamine and terbinafine also inhibited the growth of dermatophytes and molds but had significantly lower effects on the yeast. Sertaconazole nitrate might have advantages over the commonly used antifungals ciclopirox olamine and terbinafine in combating resting spores, which persist in the tissues, and thus in the therapy of recurring dermatomycoses.

A multicentre, randomised, parallel-group, double-blind, vehicle-controlled and open label versus amorolfine 5% study, to evaluate the efficacy and safety of terbinafine 10% nail lacquer in the treatment of onychomycosis

BACKGROUND

Onychomycosis is a difficult-to-treat fungal nail infection whose treatment can involve systemic or topical antifungal approaches.

OBJECTIVES

To assess the efficacy and safety of terbinafine 10% nail lacquer in distal lateral subungual onychomycosis (DLSO).

PATIENTS/METHODS

Patients with mild-to-moderate DLSO were randomised (3:3:1) to receive double-blind topical terbinafine 10% (n = 406) or its vehicle (n = 410) administered once daily for 4 weeks and then once weekly for 44 weeks, or open-label topical amorolfine 5% (n = 137) for 48 weeks, with a 12-week follow-up period. The primary efficacy endpoint, complete cure rate at Week 60, was a composite of negative potassium hydroxide (KOH) microscopy, negative culture for dermatophytes and no residual clinical involvement of the target big toenail.

RESULTS

Complete cure rates at Week 60 in the terbinafine, vehicle and amorolfine groups were 5.67%, 2.20% and 2.92%, respectively (odds ratio (OR) vs vehicle = 2.68; 95% confidence intervals (CI): 1.22-5.86; p = .0138). Statistically significant differences in responder (negative KOH and negative culture and ≤10% residual clinical involvement) and mycological cure rates (negative KOH and negative culture) at Week 60 were obtained between terbinafine and vehicle. Terbinafine was well-tolerated with no systemic adverse reactions identified; the most common topical adverse reactions were erythema and skin irritation.

CONCLUSIONS

Terbinafine 10% nail lacquer was an effective treatment for mild-to-moderate onychomycosis improving both clinical and mycological criteria compared with vehicle. Furthermore, there may be some benefits compared to the currently available topical agent, amorolfine 5%. Treatment was well-tolerated and safe.

Novel Antifungal Activity of Q-Griffithsin, a Broad-Spectrum Antiviral Lectin

There is a rising global incidence of Candida strains with high levels of resistance to fluconazole and other antifungal drugs, hence the need for novel antifungal treatment strategies. Here, we describe the first evidence of antifungal activity of Q-Griffithsin (Q-GRFT), a recombinant oxidation-resistant variant of Griffithsin, a marine red algal lectin with broad-spectrum antiviral activity. We demonstrated that Q-GRFT binds to α-mannan in the Candida albicans cell wall. We also observed that Q-GRFT binding disrupted cell wall integrity and induced reactive oxidative species (ROS) formation, resulting in cell death. Furthermore, we showed that Q-GRFT inhibited the growth of other Candida species C. glabrata, C. parapsilosis, and C. krusei and had modest activity against some strains of multi- and pandrug-resistant C. auris. We found that Q-GRFT induced differential expression of numerous genes involved in response to cell stress, including those responsible for neutralizing ROS production and cell cycle regulation. In conclusion, this novel antifungal activity suggests that Q-GRFT is potentially an ideal drug candidate and represents an alternative strategy for the prevention and treatment of candidiasis. IMPORTANCE Fungal infections contribute to morbidity and mortality annually, and the number of organisms that are nonresponsive to the current available drug regimens are on the rise. There is a need to develop new agents to counter these infections and to add to the limited arsenal available to treat fungal infections. Our study has identified Q-GRFT, a broad-spectrum antiviral protein that harbors growth-inhibitory activity against several Candida strains, as a potential candidate for the prevention and treatment of fungal infections.

Poloxamer 407 Based Gel Formulations for Transungual Delivery of Hydrophobic Drugs: Selection and Optimization of Potential Additives

The current study aimed to develop poloxamer 407 (P407) gel for transungual delivery of antifungal hydrophobic drugs with sufficient gel strength and drug loading. Gel strength and drug loading of P407 gel was improved by use of functional additives. Hydration enhancement effect was used to select optimum nail penetration enhancer. Face-centered central composite design (FCCCD) was used to observe the effect of the selected penetration enhancer (thioglycolic acid (TGA)) and cosolvent (ethanol) on gelation behavior to develop formulation with enough loading of hydrophobic drug, i.e., terbinafine HCl (TBN), and its permeation across the nail plate without compromising on gel strength. It was observed that increasing concentration of P407 and TGA significantly reduced gelation temperature and enhanced the gel strength of P407 gel and can be used to improve P407 gel strength. Under the scanning electron microscope, the significant effect of TGA as an ungual penetration enhancer was observed on the morphology of the nail plate. Optimized P407 gel prepared with modified cold method showed a gelation temperature of 8.7 ± 0.16 °C, gel strength of 122 ± 7.5 s and drug loading of 1.2% w/w, which was four times more than the drug loading in the gels prepared with conventional cold method. Rheological behavior was pseudoplastic with 47.75 ± 3.48% of gel erosion after 12 washings and 67.21 ± 2.16% of drug release after 12 h. A cumulative amount of TBN permeated from P407 gel with and without PE after 24 h was 27.30 ± 4.18 and 16.69 ± 2.31 µg/cm², respectively. Thioglycolic acid can be used as a nail penetration enhancer without the chemical modification or addition of extra additives while retaining the gel strength. Water miscible cosolvents with moderate evaporability such as ethanol, can be incorporated to P407 gel by minor modification in method of preparation to load the required dose of hydrophobic drugs. Developed P407 gel formulation with sufficient gel strength and drug loading will be a promising carrier for transungual delivery of hydrophobic antifungal agents.

Pharmacokinetics of single dose oral Terbinafine in common shelducks (Tadorna tadorna)

Fungal disease is a major cause of morbidity and mortality in avian species; thus, antifungals are the treatment of choice. Despite widely used in clinical practice, terbinafine pharmacokinetic studies are scarce in literature and only cover some avian families, with marked differences between them. This study evaluates the pharmacokinetic behaviour of terbinafine after a single oral administration of 60 mg/kg in 7 healthy adult common shelducks (Tadorna tadorna) by measuring plasma concentrations through high-performance liquid chromatography (HPLC) at times 0, 30 min, 1, 2, 4, 6, 8, 10, 12, 24, 36 and 48 hr postadministration. Noncompartmental analyses of the data showed a C_max (geometric mean) of 5.43 µg/ml, t_max (median) 1.0 hr and AUC_0-∞ 29.70 mg h/L. Elimination half-life was 6.33 hr and MRT 6.61 hr. Plasma concentrations remained above previously described MIC for terbinafine in some fungal species for at least 6 to 8 hr. A single oral administration of 60 mg/kg terbinafine did not produce adverse effects and could be a good treatment choice for fungal diseases in anatids.

Eradicating Otomycosis with Terbinafine Solution: Basic and Clinical Investigation

BACKGROUND

Otomycosis still remains intractable in clinical practice, likely because topical antifungal agents lack efficacy or are potentially toxic to the inner ear end organs.

OBJECTIVES

The aim of this study was to investigate whether terbinafine solution is a potential candidate for treating intractable otomycosis in humans. In addition, the toxic effect on the inner ear was also assessed by animal models treated with terbinafine.

METHODS

Guinea pigs were instilled with 0.1 mL terbinafine (10 and 25 mg/mL) in the left round window membrane. At 2 weeks after treatment, all animals underwent an inner ear test battery and were then sacrificed for morphological study. Clinically, 20 patients with otomycosis were treated with terbinafine solution at a dosage of 0.4 mg.

RESULTS

All terbinafine-treated animals showed intact inner ear function when total dosage of terbinafine was <2.5 mg, which was further confirmed by morphological study. Subsidence of otomycosis was achieved in all 20 patients 1 week after treatment with terbinafine (0.4 mg) without untoward effect. No evidence of recurrence was noted 1 year after treatment.

CONCLUSION

The paucity of inner ear toxicity of terbinafine even at a dosage of 2.5 mg was identified in guinea pig models morphologically and physiologically. Topical application of terbinafine solution at a dosage of 0.4 mg may be a potential treatment for otomycosis in humans.

Is Antifungal Resistance a Cause for Treatment Failure in Dermatophytosis: A Study Focused on Tinea Corporis and Cruris from a Tertiary Centre?

Background:

Dermatophytoses are one of the most common skin diseases that have been largely simple to treat. However, in recent years, these infections have become recalcitrant to treatment which can possibly be due to antifungal resistance.

Aim:

To analyze the resistance pattern of patients with recalcitrant dermatophytoses.

Materials and Methods:

A cross-sectional evaluation was undertaken of 40 consecutive patients with recalcitrant tinea corporis/cruris/both who had taken systemic antifungal treatment and did not respond completely to therapy or had recurrent lesion within 1 month of stopping the therapy. Terbinafine, fluconazole, itraconazole, ketoconazole, amphotericin B, and voriconazole were the antifungals tested using broth microdilution assay for antifungal susceptibility testing of dermatophytes, and MIC50, 90 values were recorded.

Results:

KOH mount was positive in 18 (45%) patients, culture was positive in 28 (70%) patients. Trichophyton mentagrophytes (35%) and T. rubrum (27.5%) were the predominant isolates. Overall, activity of terbinafine and itraconazole were significantly higher than the other drugs tested. For terbinafine, both T. mentagrophytes and T. rubrum were inhibited at MIC₉₀ of 0.125 μg/ml. Itraconazole-inhibited T. mentagrophytes and T. rubrum at MIC₉₀ of 0.0625 and 0.25 μg/ml, respectively. All isolates had reduced susceptibility to fluconazole.

Conclusion:

While MIC seen were higher than western data, in-vitro resistance (>1 μg/ml) to antifungals was not seen and probably may not be a cause of treatment failure. Possibly, treatment failure lies in the intricate host fungal interaction and virulence of species which help it to evade host immune response.

Efficacy of Topical Therapy with Newly Developed Terbinafine and Econazole Formulations in the Treatment of Dermatophytosis in Cats

In the field of veterinary dermatology dermatophytosis is one of the most frequently occurring infectious diseases, therefore its treatment should be effective, convenient, safe and inexpensive. The aim of this study was to evaluate the efficacy of newly developed topical formulations in the treatment of cats with dermatophytosis. Evaluation of clinical efficacy and safety of terbinafine and econazole formulations administered topically twice a day was performed in 40 cats. Cats, suffering from the most widely spread Microsporum canis-induced dermatophytosis and treated with terbinafine hydrochloride 1% cream, recovered within 20.3±0.88 days; whereas when treated with econazole nitrate 1% cream, they recovered within 28.4±1.14 days. A positive therapeutic effect was yielded by combined treatment with local application of creams and whole coat spray with enilconazole 0.2% emulsion "Imaverol". Most cats treated with econazole cream revealed redness and irritation of the skin at the site of application. This study demonstrates that terbinafine tended to have superior clinical efficacy (p<0.001) in the treatment of dermatophytosis in cats compared to the azole tested.

Multilocus Phylogeny and Antifungal Susceptibility of Aspergillus Section Circumdati from Clinical Samples and Description of A. pseudosclerotiorum sp. nov

A multilocus phylogenetic study was carried out to assess species identity of a set of 34 clinical isolates from Aspergillus section Circumdati from the United States and to determine their in vitro antifungal susceptibility against eight antifungal drugs. The genetic markers used were the internal transcribed spacer (ITS) region, and fragments of the beta-tubulin (BenA), calmodulin (CaM), and RNA polymerase II second largest subunit (RPB2) genes. The drugs tested were amphotericin B, itraconazole, posaconazole, voriconazole, anidulafungin, caspofungin, micafungin, and terbinafine. The most common species sampled was A. westerdijkiae (29.4%), followed by a novel species, which was described here as A. pseudosclerotiorum (23.5%). Other species identified were A. sclerotiorum (17.6%), A. ochraceus (8.8%), A. subramanianii (8.8%), and A. insulicola and A. ochraceopetaliformis, with two isolates (5.9%) of each. The drugs that showed the most potent activity were caspofungin, micafungin, and terbinafine, while amphotericin B showed the least activity.

Itraconazole and Terbinafine Treatment of Some Nondermatophyte Molds Causing Onychomycosis of the Toes and a Review of the Literature

Background:

Onychomycosis may be caused by dermatophytes (which form the majority of organisms), Candida species, and nondermatophyte molds.

Objective:

To evaluate the efficacy and safety of itraconazole and terbinafine in the treatment of some nondermatophyte molds that cause toe onychomycosis and to review the literature on the treatment of nondermatophyte mold toe onychomycosis using the oral antifungal agents.

Patients and Methods:

Patients with nondermatophyte mold toe onychomycosis were treated in an open, prospective manner with either itraconazole (pulse) or terbinafine therapy. In each instance, light microscopic examination was consistent with the diagnosis of a nondermatophyte mold. For each patient, mycological evaluation of the target nail resulted in 3 or more successive cultures yielding growth of the mold alone.

Results:

All 15 patients had onychomycosis of the toes which was of the distal and lateral type. The patients were treated with itraconazole given as the standard 3 pulses with additional pulses administered depending upon the response exhibited by the toe onychomycosis in the patient. Similarly, terbinafine was given for 12 weeks with additional therapy administered as dictated by the response. Efficacy parameters were mycological cure (MC) and clinical cure (CC). Mycological cure was negative light microscopic examination (KOH) and culture. Clinical cure was the appearance of a completely normal-looking nail. At month 12 from the start of treatment, the response was as follows: Scopulariopsis brevicaulis: itraconazole (MC 4/4, CC 2/4) and terbinafine (MC 0/1, CC 0/1), Fusarium species: itraconazole (MC 1/1, CC 1/1) and terbinafine (MC 0/1, CC 0/1), Aspergillus species: itraconazole (MC 5/6, CC 3/6), Alternaría alternata: itraconazole (MC 0/1, CC 0/1), and Onychocola canadensis: itraconazole (MC 1/1, CC 0/1). There were no significant clinical or laboratory adverse effects.

Conclusions:

In the present series itraconazole demonstrated efficacy against onychomycosis of the toenails caused by 5. brevicaulis and Aspergillus species. A review of the literature confirms our experience with itraconazole and further suggests that terbinafine may also demonstrate efficacy against cases of S. brevicaulis and Aspergillus toe onychomycosis. Additionally, reports in the literature suggest that pedal onychomycosis caused by Fusarium species may also show response to itraconazole and terbinafine. For the other species, there are fewer data, making it difficult to draw conclusions.

Emerging Threats in Antifungal-Resistant Fungal Pathogens

The use of antifungal drugs in the therapy of fungal diseases can lead to the development of antifungal resistance. Resistance has been described for virtually all antifungal agents in diverse pathogens, including Candida and Aspergillus species. The majority of resistance mechanisms have also been elucidated at the molecular level in these pathogens. Drug resistance genes and genome mutations have been identified. Therapeutic choices are limited for the control of fungal diseases, and it is tempting to combine several drugs to achieve better therapeutic efficacy. In the recent years, several novel resistance patterns have been observed, including antifungal resistance originating from environmental sources in Aspergillus fumigatus and the emergence of simultaneous resistance to different antifungal classes (multidrug resistance) in different Candida species. This review will summarize these current trends.

Therapy of infections caused by dematiaceous fungi

Dematiaceous fungi are responsible for a wide variety of clinical syndromes, from local infections due to trauma, to disseminated infection in immunocompromised patients. These fungi are unique owing to the presence of melanin in their cell walls, which imparts the characteristic dark color to their spores and hyphae. Melanin may also be a virulence factor in these fungi. Therapy depends upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Azoles such as itraconazole and voriconazole have the most consistent in vitro activity, although newer agents may also play a role in therapy in the future.

Evaluation of Antifungal Efficacy in an Optimized Animal Model ofTrichophytonmentagrophytes-Dermatophytosis

Dermatophytoses are known to cause considerable discomfort, cosmetic problems and financial loss that have been recognized as a significant health concern worldwide. Since currently available antifungal agents have limitations in their efficacy, new agents are being developed. This study was undertaken to optimize an in vivo model of experimental dermatophytosis for evaluation of the efficacy of antifungal compounds. Guinea pigs were infected with different inocula of T. mentagrophytes to establish dermatophytosis. The optimal conditions for dermatophytosis in guinea pigs were found to be an inoculum size of 1 x 10(7) fungal cells applied on abraded skin. After optimization, animals were treated with oral or topical formulations of terbinafine. The optimized guinea pig model was found to be highly reproducible, and useful in the primary screening and evaluation of the anti-dermatophytic efficacy of topical and oral formulations of antifungal agents.

Molecular identification and in vitro response to antifungal drugs of clinical isolates of Exserohilum

Exserohilum is an agent of human and animal mycoses. Although classification has been based on a few subtle morphological differences, three species of clinical interest have been traditionally accepted. In this study, by using a multigene sequence analysis, we have demonstrated that Exserohilum longirostratum and E. mcginnisii are probable synonyms of E. rostratum. The isolates tested were mainly from the nasal region. Antifungal susceptibility testing demonstrated high activity of the eight agents tested against this fungus.

In vitro susceptibility of Madurella mycetomatis to posaconazole and terbinafine

Presently, therapy of eumycetoma in Sudan is still based on surgery combined with prolonged ketoconazole therapy. This usually results in a poor clinical outcome. To determine if posaconazole and terbinafine could offer better therapeutic alternatives, the in vitro susceptibilities of 34 Madurella mycetomatis strains were determined. It appeared that posaconazole was highly active against M. mycetomatis but terbinafine was only moderately active. Since posaconazole has an excellent safety profile, it might provide an important alternative in mycetoma therapy.

Melanized fungi in human disease

Melanized or dematiaceous fungi are associated with a wide variety of infectious syndromes, including chromoblastomycosis, mycetoma, and phaeohyphomycosis. [corrected]. Many are soil organisms and are generally distributed worldwide, though certain species appear to have restricted geographic ranges. Though they are uncommon causes of disease, melanized fungi have been increasingly recognized as important pathogens, with most reports occurring in the past 20 years. The spectrum of diseases with which they are associated has also broadened and includes allergic disease, superficial and deep local infections, pneumonia, brain abscess, and disseminated infection. For some infections in immunocompetent individuals, such as allergic fungal sinusitis and brain abscess, they are among the most common etiologic fungi. Melanin is a likely virulence factor for these fungi. Diagnosis relies on careful microscopic and pathological examination, as well as clinical assessment of the patient, as these fungi are often considered contaminants. Therapy varies depending upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Triazoles such as voriconazole, posaconazole, and itraconazole have the most consistent in vitro activity. Further studies are needed to better understand the pathogenesis and optimal treatment of these uncommon infections.

Pharmacokinetics of orally administered terbinafine in African penguins (Spheniscus demersus) for potential treatment of aspergillosis

The objective of this study was to determine the pharmacokinetic parameters of orally administered terbinafine hydrochloride based on 3, 7, and 15 mg/kg single- as well as multiple-dosage trials in order to calculate dosing requirements for potential treatment of aspergillosis in African penguins (Spheniscus demersus). Ten adult African penguins were used in each of these trials, with a 2-wk washout period between trials. Mean plasma concentrations of terbinafine peaked in approximately 4 hrs at 0.11 +/- 0.017 microg/ml (mean +/- SD) following administration of 3 mg/kg terbinafine, while 7 mg/kg and 15 mg/kg dosages resulted in peak plasma concentrations of 0.37 +/- 0.105 and 0.33 +/- 0.054 microg/ml, respectively. The volume of distribution increased with increasing dosages, being 37 +/- 28.5, 40 +/- 28.1, and 52 +/- 18.6 mg/L for 3, 7, and 15 mg/kg doses, respectively. The mean half-life was biphasic with initial terminal half-life (t(1/2)) values of 9.9 +/- 4.5, 17.2 +/- 4.9 and 16.9 +/- 5.4 hrs, for 3, 7, and 15 mg/kg doses, respectively. A rapid first elimination phase was followed by a slower second phase, and final elimination was estimated to be 136 +/- 9.7 and 131 +/- 9.9 hrs, for 7 and 15 mg/kg doses, respectively. Linearity was demonstrated for area under the curve but not for peak plasma concentrations for the three dosages used. Calculations based on pharmacokinetic parameter values indicate that a 15 mg/kg terbinafine q24h dosage regimen would result in steady-state trough plasma concentrations above the minimum inhibitory concentration (0.8-1.6 microg/ ml), and this dosage is recommended as a potential treatment option for aspergillosis in penguins. However, additional research is required to determine both treatment efficacy and safety.

Less-frequent Fusarium species of clinical interest: correlation between morphological and molecular identification and antifungal susceptibility

Forty-eight Fusarium isolates morphologically identified as belonging to seven species of clinical interest (i.e., Fusarium chlamydosporum, Fusarium dimerum, Fusarium incarnatum, Fusarium napiforme, Fusarium nygamai, Fusarium proliferatum, and Fusarium sacchari) were characterized molecularly by the analysis of the sequences of the TUB region of the beta-tubulin gene. F. chlamydosporum and F. dimerum were the most genetically heterogeneous species. A high degree of correlation between the morphological and molecular identification was shown among the isolates studied. A table with the key morphological features for the identification of these Fusarium species is provided. The antifungal susceptibilities of the Fusarium isolates to 11 antifungal drugs were tested; terbinafine was the most active drug against all the species tested with the exception of F. incarnatum, for which amphotericin B was the most active.

Antifungal suscepitibility profile of candida spp. oral isolates obtained from denture wearers

Denture stomatitis is an inflammatory condition that occurs in denture wearers and is frequently associated with Candida yeasts. Antifungal susceptibility profiles have been extensively evaluated for candidiasis patients or immunosupressed individuals, but not for healthy Candida carriers. In the present study, fluconazole, itraconazole, voriconazole, terbinafine and 5-flucytosin were tested against 109 oral Candida spp. isolates. All antifungal agents were effective against the samples tested except for terbinafine. This work might provide epidemiological information about Candida spp. drug susceptibility in oral healthy individuals.

Efficacy of terbinafine and itraconazole on a experimental model of systemic sporotrichosis

Itraconazole is currently considered the drug of choice to treat the diverse clinical presentation of sporotrichosis. On the other hand terbinafine by virtue of its excellent in vitro activity is under comparative evaluation for its therapeutic potential for a wide range of fungal infections. In this study, our aim was to determine the in vivo efficacy of terbinafine and itraconazole on a experimental model of systemic sporotrichosis. 120 rats Wistar received an injection of 2×10³S. schenckii cells by via the lateral tail vein. After 3 days the animals were treated with terbinafine (250mg/kg) and itraconazole (100 mg/kg) and their respective diluents. In our model, terbinafine and itraconazole were effective in reducing the number of clinical lesions and positive organ cultures. There was statistical difference between the groups treated with the antifungals in relation to the control groups (p<0,05) concerning the clinical alterations, anatomic-pathological findings and in the positive organ cultures of the agent, being that the treated animals resulted in the absence and/or reduction of all the evaluated parameters. As for the treatments, terbinafine showed similar or higher activity that itraconazole in the evaluation of the testicle alteration (p=0,0004), as well as in the positive organ cultures of microorganism from the organ (p=0,0142). With these results it is possible to conclude that the antifungals studied are effective in the treatment of experimental systemic sporotrichosis.

Use of terbinafine in rare and refractory mycoses

Terbinafine is the only systemic allylamine antifungal currently available. Its mechanism of action is unique and sets it apart from other agents. Although it is primarily used for dermatophyte infections, such as onychomycosis and tinea pedis, terbinafine has broad in vitro activity against a variety of non-dermatophyte fungal pathogens, including Candida spp. and many molds. In addition, synergistic activity is noted with other antifungals, notably triazoles. Multiple case reports exist of its use for unusual and refractory fungal infections, but no systematic review is available. We review the current literature with regard to in vitro data and clinical experience with terbinafine in the treatment of rare and refractory mycoses.

In vitro antifungal susceptibilities of five species of sporothrix

Ninety-two isolates belonging to five species of the Sporothrix schenckii complex were tested in vitro against 12 antifungal agents, using a reference microdilution method. There were significant differences among the species; Sporothrix brasiliensis was the species that showed the best response to antifungals, and S. mexicana had the worst response. In general, terbinafine was the most active drug, followed by ketoconazole and posaconazole.

Fusarium spp. as agents of onychomycosis in immunocompetent hosts

BACKGROUND

Fusarium spp. are nondermatophyte filamentous fungi, frequently reported as an etiologic agent of opportunistic infections in humans; however, their involvement in the etiology of cutaneous lesions is still debatable, especially in immunocompetent patients, where they are often considered as contaminant fungi.

OBJECTIVE

The aims of this study were to report the high prevalence of onychomycosis by Fusarium spp. in immunocompetent patients in the region of Maringá, Paraná, Brazil, to establish clinical and laboratory criteria for this genus as a causal agent of onychomycosis, and to determine the susceptibility profile to the systemic antifungal drugs most frequently used in Brazil (itraconazole, ketoconazole, terbinafine, and amphotericin B).

METHODS

The fungi were isolated and identified through the classical method, and sensitivity tests were carried out according to the National Committee for Clinical Laboratory Standards (NCCLS) M38-A protocol.

RESULTS

Of the 360 confirmed cases of onychomycosis, 27 (7.5%) were attributed to the genus Fusarium, and F. oxysporum was the most commonly isolated species. Nail lesions with paronychia and pain, combined with direct suggestive microscopy and a high concentration of microorganisms, were predictive of onychomycosis by Fusarium spp. The minimum inhibitory concentration was high for itraconazole, ketoconazole, and terbinafine, but low for amphotericin B.

CONCLUSIONS

It is recommended that more attention should be given to the interpretation and identification of species of the Fusarium genus in superficial clinical samples. This fungus may be considered as an agent of onychomycosis, even in immunocompetent individuals, by identifying criteria that separate situations of clinical significance from those of simple contamination.

Successful treatment of a disseminated Sporothrix schenckii infection and in vitro analysis for antifungal susceptibility testing

We report a case of a diabetic patient with localized osteoarticular sporotrichosis followed by widespread dissemination of the infection, which was successfully treated with amphotericin B. In addition, we evaluated the in vitro antifungal activity of 4 agents against both the mycelial and the yeast forms of the isolated fungus.

Dematiaceous fungi

Dematiaceous fungi are responsible for a wide variety of infectious syndromes. They are often found in soil and generally distributed worldwide. This suggests that most if not all individuals are exposed to them, presumably from inhalation or trauma. In recent years, these fungi have been increasingly recognised as important pathogens. The spectrum of diseases they are associated with has also broadened and includes superficial and deep local infections, allergic disease, pneumonia, brain abscess and disseminated infection. For some infections in immunocompetent individuals, such as allergic fungal sinusitis and brain abscess, they are among the most common aetiological agents. These fungi may have unique pathogenic mechanisms owing to the presence of melanin in their cell walls, which imparts the characteristic dark colour to their spores and hyphae. Diagnosis rests on careful microscopical and pathological examination, as there are no simple laboratory tests to reliably identify these fungi. Therapy depends upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Azoles such as itraconazole and voriconazole have the most consistent in vitro activity, though there is more clinical experience with itraconazole. Further studies are needed to better understand the pathogenesis and optimal treatment of these uncommon infections.

In vitro susceptibility of isolates of Sporothrix schenckii to amphotericin B, itraconazole, and terbinafine: comparison of yeast and mycelial forms

Forty-three clinical isolates of Sporothrix schenckii derived from humans and animals were evaluated in vitro for their susceptibility to amphotericin B, itraconazole, and terbinafine. MICs were determined by the method of micro dilution in liquid media, using protocols M27-A2 for the yeast form and M38-A for the mycelial form, both standardized by the Clinical Laboratory Standards Institute. In general, higher MICs were found for the mycelial form (intervals of up to two dilutions). In the case of amphotericin B, a significant difference in activity was observed, with higher values (p<0.05) found for the mycelial form. MICs for itraconazole and terbinafine were similar for both yeast and mycelial forms but slightly higher for mycelia. Although data presented here indicate different levels of susceptibility when both growth forms were compared, indicating an intrinsic difference between them, it is still difficult to draw a consensus as to which form correlates better with clinical findings. More studies are necessary to determine the criteria for in vitro tests that will lead to efficient therapeutic choices.

Synergistic antimicrobial activity by combining an allylamine with benzoyl peroxide with expanded coverage against yeast and bacterial species

BACKGROUND

Dermatophyte infections can be polymicrobial. Topical antifungal therapies offer limited coverage of yeasts and Gram-positive and Gram-negative bacteria. Moreover, the increased usage of these topical antimicrobial agents has resulted in the development of resistant cases. Benzoyl peroxide (BP), used in concert with antimicrobial agents containing an accessible tertiary amine, has previously been shown to increase radical activity and biological effect.

OBJECTIVES

To determine the applicability of using the tertiary amine terbinafine in concert with BP in dermatophyte and mixed skin infections by means of in vitro testing.

METHODS

In this preliminary in vitro study, the effect of BP, alone and in combination with terbinafine, was tested against Candida albicans, Pseudomonas aeruginosa and Staphylococcus aureus isolates following a checkerboard modification of the National Committee for Clinical Laboratory Standards M27-A2 and M7-A6. The individual minimum inhibitory concentrations of terbinafine, BP, and the combination, were determined against each isolate.

RESULTS

The combination of BP with terbinafine led to additive activities against the majority of Candida albicans isolates tested and additionally expanded the bacterial coverage of terbinafine.

CONCLUSIONS

The combination of antifungal agents bearing a tertiary amine with BP may have benefit in polymicrobial infections, given its wider antimicrobial coverage. Further appreciation of this mechanism of catalysis of BP radical formation by certain antimicrobials and other tertiary amine-containing compounds may lead to the discovery of improved treatments for several dermatological conditions.

An update on antifungal targets and mechanisms of resistance in Candida albicans

Much progress has been made in the last decade in identifying genes responsible for antifungal resistance in Candida albicans. Attention has focused on five major C. albicans genes: ABC transporter genes CDR1 and CDR2, major facilitator efflux gene MDR1, and ergosterol biosynthesis genes ERG11 and ERG3. Resistance involves mutations in 14C-lanosterol demethylase, targeted by fluconazole (FLZ) and encoded by ERG11, and mutations that up-regulate efflux genes that probably efflux the antifungals. Mutations that affect ERG3 mutations have been understudied as mechanism resistance among clinical isolates. In vitro resistance in clinical isolates typically involves step-wise mutations affecting more than one of these genes, and often unidentified genes. Different approaches are needed to identify these other genes. Very little is understood about reversible adaptive resistance of C. albicans despite its potential clinical significance; most clinical failures to control infections other than oropharyngeal candidiasis (OPC) occur with in vitro susceptible strains. Tolerance of C. albicans to azoles has been attributed to the calcineurin stress-response pathway, offering new potential targets for next generation antifungals. Recent studies have identified genes that regulate CDR1 or ERG genes. The focus of this review is C. albicans, although information on Saccharomyces cerevisiae or Candida glabrata is provided in areas in where Candida research is underdeveloped. With the completion of the C. albicans genomic sequence, and new methods for high throughput gene overexpression and disruption, rapid progress towards understanding the regulation of resistance, novel resistance mechanisms, and adaptive resistance is expected in the near future.

Dermatophytes growth curve and in vitro susceptibility test: a broth micro-titration method

The introduction of systemic antifungal drugs which act upon different targets is the main issue of the in vivo antifungal resistance control. Different factors, such as growth curve phase, quality of the specimen, quantity of the inoculum, temperature, pH, culture medium composition, incubation duration and solvent, are believed important factors affecting minimum inhibitory concentration (MIC) value to most of the antifungal agents. We assayed an in vitro susceptibility test with 40 isolates of dermatophytes: Microsporum canis, Trichophyton rubrum, Trichophyton mentagrophytes and Epidermophyton floccosum against griseofulvin, fluconazole, itraconazole and terbinafine, using the guidelines of the M38-P document approved by the NCCLS. We determined the growth curves, to estimate the specific growth rate (mu max) and the generation time (G) of each dermatophyte, using dry weight and spectrophotometry methods. We demonstrate that, at 192 h, all fungi tested had a constant growth curve and we considered this as the optimal time for MIC determination. Terbinafine, griseofulvin and itraconazole possessed the highest antifungal activity against the four groups of dermatophytes studied. Fluconazole demonstrated no efficacy. Our MIC results differ from other authors and this difference is due to the timing of the MIC determination based on the growth curve of each fungi tested.

Comparison of in vitro activities of antifungal drugs and ethanolic extract of propolis against Trichophyton rubrum and T. mentagrophytes by using a microdilution assay

The in vitro activities of propolis against 29 strains of dermatophytes were compared with those of terbinafine, itraconazole, ketoconazole, and fluconazole. Minimal inhibitory concentrations (MICs) were determined according to a National Committee for Clinical Laboratory Standards broth microdilution method. Among the systemic antifungals tested, terbinafine was the most potent. Propolis showed important antifungal activity and it merits further investigation as a potentially useful agent for the treatment of dermatophytosis.

Comparison of disk diffusion method and broth microdilution method for antifungal susceptibility testing of dermatophytes

The use of the agar diffusion Neo-Sensitabs method to determine antifungal susceptibility of 59 isolates of dermatophytes, namely Epidermophyton floccosum, Microsporum canis, M. gypseum, Trichophyton mentagrophytes, T. rubrum and T. tonsurans to Clotrimazole (CLZ), Itraconazole (ITZ) and Terbinafine (TBF) is described. Results obtained are compared to the minimum inhibitory concentrations (MIC) determined by an adaptation of the NCCLS-M38-A procedure. Using the diffusion method, all strains showed a broad zone of inhibition at the first available reading time (3 or 7 days). Using the broth microdilution method, the geometric mean MIC (microg/ml) with regard to all isolates was < or = 0.03 for TBF, < or = 0.069 for CLZ and < or = 0.919 for ITZ. In both methods, TBF was the most active antifungal agent against all isolates tested. The two methods evaluated were able to detect the resistance of the quality control strains of Aspergillus fumigatus to ITZ. Even though a reference method for testing dermatophytes still has not been developed, our data suggest that the Neo-Sensitabs diffusion method could provide a simple procedure for the antifungal susceptibility testing of dermatophytes in the routine clinical laboratory.

In vitro susceptibilities of isolates of Sporothrix schenckii to itraconazole and terbinafine

Thirty isolates of the yeast form of Sporothrix schenckii were evaluated for in vitro susceptibility to itraconazole and terbinafine by the recommended NCCLS modified technique (M27-A2). The MICs of itraconazole obtained oscillated between 0.062 and 4.0 microg/ml, and those of terbinafine oscillated between 0.007 and 0.50 microg/ml; therefore, terbinafine showed greater in vitro activity.

In vitro activity of terbinafine and itraconazole against Aspergillus species isolated from otomycosis

The minimum inhibitory concentrations (MIC, microg ml-1) of itraconazole and terbinafine against overall 34 Aspergillus isolates from the external ear canals with otomycosis have been determined with M38-P microdilution method suggested by National Committee for Clinical Laboratory Standards (NCCLS). MIC intervals in 48 h determined by taking MIC-2 value of itraconazole (the lowest drug concentration causing 50% inhibition of visible fungal growth) and MIC-0 value of terbinafine (the lowest drug concentration causing 100% inhibition of visible fungal growth) as a basis have been found as follows: 0.125-1 and 0.06-0.5 microg ml-1 for A. niger (22 strains), 0.06-0.25 and 0.06-0.125 microg ml-1 for A. flavus (10 strains), 0.125 and 0.125-0.5 microg ml-1 for A. terreus (two strains). It has been observed that both of the antifungal agents showed an in vitro activity against all Aspergillus species tested.

In vitro antifungal susceptibilities of uncommon basidiomycetous yeasts

The in vitro activities of eight antifungal drugs against 50 isolates of basidiomycetous yeasts were determined by a microdilution method. In general fluconazole and micafungin were inactive. Terbinafine was active only against Sporobolomyces salmonicolor. The activities of the other antifungals were variable and depended on the species tested. The new triazoles showed the lowest MICs, but amphotericin B and itraconazole were the only drugs active against Cryptococcus albidus.