Combatting antifungal resistance: Paradigm shift in the diagnosis and management of onychomycosis and dermatomycosis.

Antifungal resistance has become prevalent worldwide. Understanding the factors involved in spread of resistance allows the formulation of strategies to slow resistance development and likewise identify solutions for the treatment of highly recalcitrant fungal infections. To investigate the recent explosion of resistant strains, a literature review was performed focusing on four main areas: mechanisms of resistance to antifungal agents, diagnosis of superficial fungal infections, management, and stewardship. The use of traditional diagnostic tools such as culture, KOH analysis and minimum inhibitory concentration values on treatment were investigated and compared to the newer techniques such as molecular methods including whole genome sequencing, and polymerase chain reaction. The management of terbinafine-resistant strains is discussed. We have emphasized the need for antifungal stewardship including increasing surveillance for resistant infection.

Monotherapy for Alopecia Areata: A Systematic Review and Network Meta-Analysis.

BACKGROUND: There are many treatments available for alopecia areata; however, none are approved by the US Food and Drug Administration. Thus, there is clinician benefit in efficacy comparison. METHODS: A network meta-analysis was used to create direct and indirect comparisons of alopecia areata studies in addition to an inconsistency analysis, risk of bias, and quality of evidence assessment. RESULTS: For mild disease, intralesional corticosteroids were ranked the most likely to produce a response at 78.9% according to SUCRA (surface under the cumulative ranking curve) followed by topical corticosteroids (67.9%), prostaglandin analogs (67.1%), diphenylcyclopropenone (DPCP, 63.4%), topical minoxidil (61.2%), and squaric acid dibutylester (SADBE, 35.0%). In contrast, for moderate to severe disease (>50% scalp hair loss), DPCP was the top-ranked treatment (87.9%), followed by laser (77.9%), topical minoxidil (55.5%), topical corticosteroids (50.1%), SADBE (49.7%), and topical tofacitinib (47.6%). There were insufficient eligible trials to include oral tofacitinib in the network. CONCLUSION: Statistically significant evidence is presented for the use of intralesional and topical corticosteroids for treatment of mild disease and DPCP, laser, SADBE, topical minoxidil and topical corticosteroids for moderate to severe disease. Further controlled trials are required to analyze the relative efficacy of oral tofacitinib.

A Stealthy Fungal Attack Requires an Equally Clandestine Approach to Onychomycosis Treatment.

Onychomycosis is a chronic fungal infection of the nail that is recalcitrant to treatment. It is unclear why normally effective antifungal therapy results in low cure rates. Evidence suggests that there may be a plethora of reasons that include the limited immune presence in the nail, reduced circulation, presence of commensal microbes, and fungal influence on immune signaling. Therefore, treatment should be designed to address these possibilities and work synergistically with both the innate and adaptive immune responses.

Fungal Diversity and Onychomycosis An Analysis of 8,816 Toenail Samples Using Quantitative PCR and Next-Generation Sequencing.

BACKGROUND: Onychomycosis is a fungal infection of the nail that is often recalcitrant to treatment and prone to relapse. Traditional potassium hydroxide and culture diagnosis is costly and time-consuming. Therefore, molecular methods were investigated to demonstrate effectiveness in diagnosis and to quantify the microbial flora present that may be contributing to disease. METHODS: A total of 8,816 clinically suspicious toenail samples were collected by podiatric physicians across the United States from patients aged 0 to 103 years and compared with a control population (N = 20). Next-generation sequencing and quantitative polymerase chain reaction were used to identify and quantify dermatophytes, nondermatophyte molds, and bacteria. RESULTS: Approximately 50% of suspicious toenails contained both fungi and bacteria, with the dermatophyte Trichophyton rubrum contributing the highest relative abundance and presence in 40% of these samples. Of the remaining 50% of samples, 34% had bacterial species present and 16% had neither. Fungi only were present in less than 1% of samples. Nondermatophyte molds contributed to 11.0% of occurrences in fungus-positive samples. All of the control samples were negative for fungi, with commensal bacterial species composing most of the flora population. CONCLUSIONS: Molecular methods were successful in efficiently quantifying microbial and mycologic presence in the nail. Contributions from dermatophytes were lower than expected, whereas the opposite was true for nondermatophyte molds. The clinical significance of these results is currently unknown.

Antibiofilm Treatment for Onychomycosis and Chronic Fungal Infections.

Onychomycosis is a difficult-to-treat chronic fungal infection of the nail. The chronic nature of onychomycosis, with relevance to current treatment practices, could be attributed to host anergy, development of increased virulence in causal agents (multidrug resistance efflux pump), and biofilms. Biofilms must be disrupted prior to antifungal treatment suggesting the necessity of combination treatment. Once the biofilm has been disrupted, further techniques in addition to antifungal usage are suggested to ensure a positive prognosis including use of antimicrobial photodynamic therapy or low-frequency surface acoustic waves. Overall, with continued success in developing antibiofilm treatment for bacterial and yeast pathogens, therapy can be more quickly expanded to dermatophytes. With a rise in predisposing factors, it is important to preemptively address treatment for this disease with continued investigation into antibiofilm therapy including optimal treatment combinations and dosages targeted specifically at dermatophytes.

Onychomycosis and Chronic Fungal Disease: Exploiting a Commensal Disguise to Stage a Covert Invasion.

Onychomycosis is a chronic fungal infection that is recalcitrant to treatment and often results in relapse. New evidence suggests that disease prognosis may be linked to pathogens manipulating host immune responses. Therefore, individuals with specific mutations, including those affecting pattern recognition receptors or the interleukin (IL)-17 and IL-22 pathways, may be more susceptible to infection. Moreover, it is recommended that those with a family history of immune mutations or predisposition to fungal disease be treated aggressively for onychomycosis prior to symptom progression. In addition, incorporating genetic testing and new investigational therapy such as IL-33 and interferon-γ may improve treatment outcome.

Treating Alopecia Areata: Current Practices Versus New Directions.

Alopecia areata (AA) is non-scarring hair loss resulting from an autoimmune disorder. Severity varies from patchy hair loss that often spontaneously resolves to severe and chronic cases that can progress to total loss of scalp and body hair. Many treatments are available; however, the efficacy of these treatments has not been confirmed, especially in severe cases, and relapse rates are high. First-line treatment often includes corticosteroids such as intralesional or topical steroids for mild cases and systemic steroids or topical immunotherapy with diphenylcyclopropenone or squaric acid dibutylester in severe cases. Minoxidil and bimatoprost may also be recommended, usually in combination with another treatment. Ongoing research and new insights into mechanisms have led to proposals of innovative therapies. New directions include biologics targeting immune response as well as lasers and autologous platelet-rich plasma therapy. Preliminary data are encouraging, and it is hoped this research will translate into new options for the treatment of AA in the near future.

A Mechanistic Model of Platelet-Rich Plasma Treatment for Androgenetic Alopecia.

BACKGROUND: Platelet-rich plasma (PRP) therapy is a novel procedure used to treat androgenetic alopecia (AGA). OBJECTIVE: Propose a mechanism of action of PRP therapy for AGA. METHODS AND MATERIALS: A thorough literature search including PRP research for AGA therapy as well as PRP research in other areas of medicine was conducted. RESULTS: A mechanistic model for the action of PRP on the hair follicle was created. CONCLUSION: Platelet-rich plasma therapy stimulates hair growth through the promotion of vascularization and angiogenesis, as well as encourages hair follicles to enter and extend the duration of the anagen phase of the growth cycle. The process is accomplished through growth factor-mediated increased activation of wingless (Wnt)/ß-catenin, extracellular signaling regulated kinase (ERK), and protein kinase B (Akt) signaling pathways, which leads to the necessary cellular proliferation and differentiation.

The role of biofilms in onychomycosis.

Onychomycosis is a fungal infection of nails primarily caused by dermatophyte fungi. Fungi are traditionally understood as existing in the environment as planktonic organisms; however, recent advancements in microbiology suggest that fungi form biofilms-complex sessile microbial communities irreversibly attached to epithelial surfaces by means of an extracellular matrix. The extracellular matrix also acts as a protective barrier to the organisms within the biofilm. The biofilm is surprisingly resistant to injury and may act as a persistent source of infection possibly accounting for antifungal resistance in onychomycosis.

Investigation of intercellular salicylic acid accumulation during compatible and incompatible Arabidopsis-pseudomonas syringae interactions using a fast neutron-generated mutant allele of EDS5 identified by genetic mapping and whole-genome sequencing.

A whole-genome sequencing technique developed to identify fast neutron-induced deletion mutations revealed that iap1-1 is a new allele of EDS5 (eds5-5). RPS2-AvrRpt2-initiated effector-triggered immunity (ETI) was compromised in iap1-1/eds5-5 with respect to in planta bacterial levels and the hypersensitive response, while intra- and intercellular free salicylic acid (SA) accumulation was greatly reduced, suggesting that SA contributes as both an intracellular signaling molecule and an antimicrobial agent in the intercellular space during ETI. During the compatible interaction between wild-type Col-0 and virulent Pseudomonas syringae pv. tomato (Pst), little intercellular free SA accumulated, which led to the hypothesis that Pst suppresses intercellular SA accumulation. When Col-0 was inoculated with a coronatine-deficient strain of Pst, high levels of intercellular SA accumulation were observed, suggesting that Pst suppresses intercellular SA accumulation using its phytotoxin coronatine. This work suggests that accumulation of SA in the intercellular space is an important component of basal/PAMP-triggered immunity as well as ETI to pathogens that colonize the intercellular space.

Forward and reverse genetics to identify genes involved in the age-related resistance response in Arabidopsis thaliana.

SUMMARY Age-related resistance (ARR) occurs in numerous plant species, often resulting in increased disease resistance as plants mature. ARR in Arabidopsis to Pseudomonas syringae pv. tomato is associated with intercellular salicylic acid (SA) accumulation and the transition to flowering. Forward and reverse genetic screens were performed to identify genes required for ARR and to investigate the mechanism of the ARR response. Infiltration of SA into the intercellular space of the ARR-defective mutant iap1-1 (important for the ARR pathway) partially restored ARR function. Inter- and intracellular SA accumulation was reduced in the mutant iap1-1 compared with the wild-type, and the SA regulatory gene EDS1 was also required for ARR. Combining microarray analysis with reverse genetics using T-DNA insertion lines, four additional ARR genes were identified as contributing to ARR: two plant-specific transcription factors of the NAC family [ANAC055 (At3g15500) and ANAC092 (At5g39610)], a UDP-glucose glucosyltransferase [UGT85A1 (At1g22400)] and a cytidine deaminase [CDA1 (At2g19570)]. These four genes and IAP1 are also required for ARR to Hyaloperonospora parasitica. IAP1 encodes a key component of ARR that acts upstream of SA accumulation and possibly downstream of UGT85A1, CDA1 and the two NAC transcription factors (ANAC055, ANAC092).