Fungal skin and soft tissue infections

Deep cutaneous mycoses in kidney transplant recipients: Diagnostic and therapeutic challenges

Deep cutaneous mycoses (DCMs) are rare infections that extend throughout the dermis and subcutis, often occurring after inoculation with pathogenic fungi. Trends toward a growing incidence have been observed that may be partially related to an increasing population of solid organ transplant patients. The aim of this study is to describe the diagnostics and the outcomes of DCM among kidney transplant recipients so as to optimize their management. We performed a retrospective review of cases of DCM occurring among kidney transplant recipients in our institution over 12 years. Twenty cases were included. Lesions were only located on the limbs and presented mainly as single (10/20, 50%) nodular lesions (15/20, 75%), with a mean size of 3 cm. Direct mycological examination was positive for 17 patients (17/20, 85%) and the cultures were consistently positive. Thirteen different fungal species were observed, including phaehyphomycetes (n = 8), hyalohyphomycetes (n = 3), dermatophytes (n = 1), and mucorale (n = 1). The (1-3) beta-D-glucan antigen (BDG) was also consistently detected in the serum (20/20, 100%). Systematic imaging did not reveal any distant infectious lesions, but locoregional extension was present in 11 patients (11/14, 79%). Nineteen patients received antifungal treatment (19/20, 95%) for a median duration of 3 months, with surgery for 10 (10/20, 50%). There is a great diversity of fungal species responsible for DCMs in kidney transplant recipients. The mycological documentation is necessary to adapt the antifungal treatment according to the sensitivity of the species. Serum BDG positivity is a potentially reliable and useful tool for diagnosis and follow-up.

Microsurgical Debridement for Persistent Ulcers Due to Rare Fungus Infection: Case Report and Literature Review

A patient suffered from chronic ulcer due to recalcitrant fungal infection for 3.5 years. Five antifungal agents and 40 times of debridement-all failed. Finally, radical microscopic debridement was performed for eradication of fungal conidiospores. Since then, there was no recurrence at 2 years of follow-up. Scopulariopsis brevicaulis is one of the rarest pathogens of cutaneous fungal infections, for which multidrug resistance increased the complexity and difficulty of treatment. Radical excision, especially microscopic debridement, was the key for eradication of fungal conidiospores in this case.

The burden of skin and subcutaneous diseases: findings from the global burden of disease study 2019

Background

The small number of existing integrative studies on the global distribution and burden of all types of skin and subcutaneous diseases hinders relevant comparisons.

Objective

This study aimed to determine the latest distribution, epidemiological differences, and factors potentially influencing each skin and subcutaneous disease and the policy implications.

Methods

Data on the skin and subcutaneous diseases were obtained from the Global Burden of Disease Study 2019. The incidence, disability-adjusted life years (DALYs), and deaths due to skin and subcutaneous diseases in 204 countries and regions from 1990 to 2019 were analyzed and stratified by sex, age, geographical location, and sociodemographic index (SDI). The annual age-standardized rate of change in the incidence was obtained to evaluate temporal trends.

Results

Of 4,859,267,654 (95% uncertainty interval [UI], 4,680,693,440-5,060,498,767) new skin and subcutaneous disease cases that were identified, most were fungal (34.0%) and bacterial (23.0%) skin diseases, which accounted for 98,522 (95% UI 75,116-123,949) deaths. The burden of skin and subcutaneous diseases measured in DALYs was 42,883,695.48 (95%UI, 28,626,691.71-63,438,210.22) in 2019, 5.26% of which were years of life lost, and 94.74% of which were years lived with disability. The highest number of new cases and deaths from skin and subcutaneous diseases was in South Asia. Globally, most new cases were in the 0-4-year age group, with skin and subcutaneous disease incidence slightly higher in men than in women.

Conclusion

Fungal infections are major contributors to skin and subcutaneous diseases worldwide. Low-middle SDI states had the highest burden of skin and subcutaneous diseases, and this burden has increased globally. Targeted and effective management strategies based on the distribution characteristics of each country are, thus, required to reduce the burden of skin and subcutaneous diseases.

Metronidazole nanosuspension loaded dissolving microarray patches: An engineered composite pharmaceutical system for the treatment of skin and soft tissue infection

Bacteroides fragilis is one of the most common causative group of microorganisms that is associated with skin and soft tissue infections (SSTI). Metronidazole (MTZ) is the drug of choice used in the treatment of SSTI caused by the bacterium. However, owing to its physiochemical properties, MTZ have limited skin permeation, which render the drug unsuitable for the treatment of deep-rooted SSTIs. One strategy to overcome this limitation is to reformulate MTZ into nanosuspension which will then be loaded into dissolving microarray patches (MAPs) for the treatment of SSTIs caused by B. fragilis. Herein, we report for the first time on the preparation and optimisation of MAP loaded with MTZ nanosuspension (MTZ-NS). After screening a range of polymeric surfactants, we identified that Soluplus® resulted in the formation of MTZ-NS with the smallest particle size (115 nm) and a narrow PDI of 0.27. Next, the MTZ-NS was further optimised using a design of experiments (DoE) approach. The optimised MTZ-NS was then loaded into dissolving MAPs with varying MTZ-NS content. Furthermore, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and cell proliferation assays along with LIVE/DEAD™ staining on the 3T3L1 cell line showed that the MTZ-NS loaded dissolving MAPs displayed minimal toxicity and acceptable biocompatibility. In vitro dermatokinetic studies showed that the MTZ-NS loaded MAPs were able to deliver the nitroimidazole antibiotic across all strata of the skin resulting in a delivery efficiency of 95 % after a 24-hour permeation study. Lastly, agar plating assay using bacterial cultures of B. fragilis demonstrated that MTZ-NS loaded MAP resulted in complete bacterial inhibition in the entire plate relative to the control group. Should this formulation be translated into clinical practice, this pharmaceutical approach may provide a minimally invasive strategy to treat SSTIs caused by B. fragilis.

Recent concepts in fungal involvement in skin and soft tissue infections

As the at-risk population expands and new antifungal resistance patterns develop, it is critical to understand and recognize cutaneous manifestations of old and emerging fungal diseases.

PURPOSE OF REVIEW

The aim of this review is to provide an overview of the most frequent and emerging deep cutaneous fungal infections following either primary inoculation or secondary spread after haematogenous seeding in disseminated infections in different geographical areas.

RECENT FINDINGS

Fungal skin and soft tissue infections (SSTIs) encompass a variety of pathological conditions based on the site of the infection, route of acquisition of the pathogen, epidemiological setting and the virulence of the fungus in relation to the host. The approach to a patient suspected of having a fungal SSTI is complex and usually poses a major diagnostic challenge. The treatment approach should include attempts at immune reconstitution, targeted antifungal therapy and/or aggressive surgical debridement.

SUMMARY

Fungal SSTIs can be an important cause of morbidity and mortality in both immunocompromised and immunocompetent patients and are being reported with increasing frequency worldwide.

Fungal Infections of Implantation: More Than Five Years of Cases of Subcutaneous Fungal Infections Seen at the UK Mycology Reference Laboratory

Subcutaneous fungal infections, which typically result from traumatic introduction (implantation) of fungal elements into the skin or underlying tissues, can present as a range of different clinical entities including phaeohyphomycosis, chromoblastomycosis, subcutaneous nodules or masses, and genuine eumycetoma. Here, we mined our laboratory information management system for such infections in humans and domestic animals for the period 2016–2022, including (i) fungal isolates referred for identification and/or susceptibility testing; (ii) infections diagnosed at our laboratory using panfungal PCR approaches on infected tissue; and (iii) organisms cultured in our laboratory from biopsies. In total, 106 cases were retrieved, involving 39 fungal species comprising 26 distinct genera. Subcutaneous infections with Alternaria species were the most frequent (36 cases), which possibly reflects the ubiquitous nature of this common plant pathogen. A substantial proportion of Alternaria spp. isolates exhibited reduced in vitro susceptibility to voriconazole. Notably, a significant number of subcutaneous infections were diagnosed in renal and other solid organ transplant recipients post transplantation, suggesting that humans may harbour “inert” subcutaneous fungal elements from historical minor injuries that present as clinical infections upon later immunosuppression. The current study underscores the diversity of fungi that can cause subcutaneous infections. While most organisms catalogued here were responsible for occasional infections, several genera (Alternaria, Exophiala, Phaeoacremonuim, Scedosporium) were more frequently recovered in our searches, suggesting that they possess virulence factors that facilitate subcutaneous infections and/or inhabit natural niches that make them more likely to be traumatically inoculated.

Nanocrystalline chloroxine possesses broad-spectrum antimicrobial activities and excellent skin tolerability in mice

Background: Antimicrobial submicrometer particles are being studied as promising interventions against a wide range of skin conditions, such as fungal or bacterial infections. Aims: To submicronize chloroxine, the crystalline compound 5,7-dichloro-8-hydroxyquinoline, by nanoprecipitation and characterize the resulting assemblies. Methods: The chloroxine particles were stabilized by a nonionic surfactant and were studied by a broth microdilution assay against 20 medically important bacteria and fungi. The intervention was studied using a murine model of skin irritation. Results & conclusions: Chloroxine nanoparticles with a diameter of 600-800 nm exhibit good tolerability in terms of skin irritation in vivo and good antimicrobial activity. Thus, the fabricated formulation shows great promise for interventions for both cutaneous infection control and prophylaxis.

Deep mycoses and pseudomycoses of the foot: a single-center retrospective study of 160 cases, in a tertiary-care center in Mexico

BACKGROUND

Deep mycoses and pseudomycoses (DMP) may cause significant disability and even death; however, the reports regarding these diseases, mainly affecting the foot, are scarce.

OBJECTIVE

To describe the epidemiological, clinical, and diagnostic characteristics of DMP of the foot in 160 patients.

METHODS

A retrospective and observational study of DMP affecting the foot was carried out in a tertiary-care center in Mexico for 20 years (from January 2000 to December 2019). Cases with confirmatory microbiological studies were included; the identification of the isolated fungi was based on the forms of reproduction. For actinomycetes, morphological analysis in an automated system ATB Vitek® 1574 (Biomèrieux) was used. The fungi were identified by PCR, using several primers from the ITS regions and for actinomycetes in the 16S rRNA region. Data from histopathological studies were also collected.

RESULTS

One hundred and sixty proven cases of DMP of the foot were included. The cases were categorized into nine types of infections including mycetoma (actinomycetoma and eumycetoma) in 102 cases (63.7%); sporotrichosis in 21 cases (13.1%); chromoblastomycosis, 18 cases (11.2%); phaeohyphomycosis, 3 cases (1.8%); histoplasmosis, 12 cases (7.5%); coccidioidomycosis 2 cases (1.2%) and botryomycosis and nocardiosis with one case respectively (0.6%). Most cases developed after traumatic implantation (147 cases, 91.8%). One hundred fifteen cases (71.8%) were men. The evolution was chronic in 125 cases (78.2%); bone involvement was observed in 64 cases (40%). Parasitic forms were observed In 139 cases (86.8%). The isolation and identification of the etiological agents were confirmed in all cases.

CONCLUSION

The main DMP affecting the foot were infections due to traumatic implantation; most were endemic mycoses. The clinical characteristics and the evolution of the diseases are easily misdiagnosed, and thus, diagnostic tests are usually required.

Protein-Based Films Functionalized with a Truncated Antimicrobial Peptide Sequence Display Broad Antimicrobial Activity

The increasing bacterial resistance to antibiotics is driving strong demand for new antimicrobial biomaterials. This work describes the fabrication of free-standing films exhibiting antimicrobial properties by combining, in the same polypeptide chain, an elastin-like recombinamer comprising 200 repetitions of the pentamer VPAVG (A200) and an 18-amino-acid truncated variant of the antimicrobial peptide BMAP-28, termed BMAP-18. The fusion protein BMAP-18A200 was overexpressed and conveniently purified by a simplified and scalable nonchromatographic process. Free-standing films of BMAP-18A200 demonstrated to be stable without requiring cross-linking agents and displayed high antimicrobial activity against skin pathogens including Gram-negative and Gram-positive bacteria as well as unicellular and filamentous fungi. The antimicrobial activity of the films was mediated by direct contact of cells with the film surface, resulting in compromised structural integrity of microbial cells. Furthermore, the BMAP-18A200 films showed no cytotoxicity on normal human cell lines (skin fibroblasts and keratinocytes). All of these results highlight the potential of these biotechnological multifunctional polymers as new drug-free materials to prevent and treat microbial infections.

The what, when and how in performing and interpreting microbiological diagnostic tests in skin and soft tissue infections

PURPOSE OF REVIEW

To summarize and classify the most recent and relevant microbiological studies for each type of skin and soft tissue infection (SSTI).

RECENT FINDINGS

Following Infectious Diseases Society of America and Food and Drug Administration classifications of SSTIs, we differentiate between two large groups, the superficial or uncomplicated infections and the complicated infections with deep involvement. It is not usually necessary to obtain microbiological samples in uncomplicated infections, except in cases of recurrences or for epidemiological control purposes. In the case of complicated infections, the samples are of two different types: those obtained from the affected area (surgical samples, punctures of abscesses or swabs) and systemic samples (i.e. blood cultures). The clinical condition also determines the type of samples to be obtained. In cases of systemic involvement, blood cultures are mandatory. For immunocompromised patients, who may present atypical infections, detection of antigens, serologies or molecular biology techniques may be helpful. The rapid diagnosis is currently the goal to be pursued by implementing techniques such as matrix assisted laser desorption ionization-time of flight, commercial real-time PCR or the promising metagenomics.

SUMMARY

Microbiological diagnosis is one of the cornerstones of the management of SSTIs. Prompt obtaining and processing of the necessary samples, depending on the clinical situation of the patient, is of relevance in the decision-making process. Rapid and fluid reporting of the results (identification, mechanisms of resistance and antibiogram) will improve the management of these patients.

Why are so many cases of invasive aspergillosis missed?

Invasive aspergillosis (IA) incidence is increasing in several countries like France, and numerous cases are indeed missed and still only diagnosed at autopsy as evidenced by recently published data. Such missed diagnoses are obviously encountered when appropriate diagnostic tools are not available especially in low resource areas or when biologists have not been trained enough in medical mycology (i.e., microscopic examination and culture in most of those areas). Besides logistical issues, which are indeed critical, IA may not be recognized because clinicians failed to consider that risk factors are evolving with the IA burden now observed among patients with chronic lymphoid malignancies or receiving new biotherapies, with diabetes mellitus or liver cirrhosis and/or acute alcoholic hepatitis, with patients from the intensive care unit (ICU) and among patients with some predisposing primary immune deficiencies now reaching the adult's age. This is also the case for human immunodeficiency virus (HIV)-infected patients who failed to meet the classical definitions of IA. From the radiology perspective, new entities of IA have also emerged which absolutely need to be recognized especially bronchial-based-IA among allogeneic stem cell transplant recipients. Finally, from the laboratory side, contribution and limits of indirect blood biomarkers should be integrated to the clinical life in order not to miss IA cases. To conclude, several diagnostic tools should be combined and a constant dialog between laboratory and clinics is crucial to appropriately diagnose IA.

Severe dermatophytosis in solid organ transplant recipients: A French retrospective series and literature review

OBJECTIVE

Severe dermatophytosis is described in immunocompromised patients with defective cellular immunity. We report here a large series and a literature review of severe dermatophytosis in solid-organ transplant (SOT) recipients.

METHOD

The data main source was a national French retrospective study of severe dermatophytosis in SOT recipients between 2010 and 2016. Inclusion criteria were the presence of dermatophytes in skin culture and 1 severity criteria: dermal invasion by dermatophytes (invasive dermatophytosis) or involvement of at least two body sites or >10% of body surface area (extensive dermatophytosis).

RESULTS

A total of 12 patients were included (8 men, median age of 56 years [range: 33-71]). Of the 12 patients, 10 underwent kidney transplantation. The median time from transplantation to severe dermatophytosis diagnosis was 16 months [range: 2-94]. Clinical signs of superficial dermatophytosis were present in 8/12 patients before the emergence of severe dermatophytosis. Nine patients had invasive forms and three extensive ones, and nodules of the lower extremities were found in eight. Trichophyton rubrum was isolated in 11 cases. First-line treatment was terbinafine (7/12), posaconazole (3/12), or topical treatment alone (2/12). Immunosuppressive therapy was reduced in 3 patients because of associated infections. Complete response was obtained for 3/3 and 5/9 patients with extensive or invasive forms, respectively, after a median treatment's duration of 2.5 [range: 1.5-5] months and 7.5 months [range: 4-12]. Unrelated deaths (n = 2) and graft function impairment (n = 3) occurred.

CONCLUSION

Severe dermatophytosis is a late complication in SOT recipients presenting with lower limb nodules, which might be prevented by prompt treatment of superficial dermatophytosis.

Use of magnetic nanoparticles as a drug delivery system to improve chlorhexidine antimicrobial activity

Nanotechnology offers new tools for developing therapies to prevent and treat oral infections, particularly biofilm-dependent disorders, such as dental plaques and endodontic and periodontal diseases. Chlorhexidine (CHX) is a well-characterized antiseptic agent used in dentistry with broad spectrum activity. However, its application is limited due to inactivation in body fluid and cytotoxicity toward human cells, particularly at high concentrations. To overcome these limitations, we synthesized nanosystems composed of aminosilane-coated magnetic nanoparticles functionalized with chlorhexidine (MNP@CHX). In the presence of human saliva, MNPs@CHX displayed significantly greater bactericidal and fungicidal activity against planktonic and biofilm-forming microorganisms than free CHX. In addition, CHX attached to MNPs has an increased ability to restrict the growth of mixed-species biofilms compared to free CHX. The observed depolarization of mitochondria in fungal cells treated with MNP@CHX suggests that induction of oxidative stress and oxidation of fungal structures may be a part of the mechanism responsible for pathogen killing. Nanoparticles functionalized by CHX did not affect host cell proliferation or their ability to release the proinflammatory cytokine, IL-8. The use of MNPs as a carrier of CHX has great potential for the development of antiseptic nanosystems.

Topographical and physiological differences of the skin mycobiome in health and disease

Skin constantly encounters external elements, including microbes. Culture-based studies have identified fungi present on human skin and have linked some species with certain skin diseases. Moreover, modern medical treatments, especially immunosuppressants, have increased the population at risk for cutaneous and invasive fungal infections, emphasizing the need to understand skin fungal communities in health and disease. A major hurdle for studying fungal flora at a community level has been the heterogeneous culture conditions required by skin fungi. Recent advances in DNA sequencing technologies have dramatically expanded our knowledge of the skin microbiome through culture-free methods. This review discusses historical and recent research on skin fungal communities - the mycobiome - in health and disease, and challenges associated with sequencing-based mycobiome research.

Diagnosis of invasive fungal diseases in pediatric patients

INTRODUCTION

The optimal management of invasive fungal infections (IFIs) in children requires prompt and precise diagnosis that enables timely implementation of appropriate antifungal therapy and decreased use of unnecessary toxic antifungals. Areas covered: Traditional approaches such as culture, microscopy and histopathology remain the gold standard but are often not sufficiently sensitive and specific. These limitations have led to the development of alternative non-invasive diagnostic methods that in most cases detect fungal components, such as antigens or nucleic acids. To date, galactomannan and 1,3 β-D-glucan assays are the most efficient non-culture methods for diagnosis and monitoring of antifungal therapy. New technologies from nano-sciences are applied, like T2Candida assay. However, these are not standardized or validated in children. Herein, we focus on IFI diagnosis emphasizing current perspectives, interpretation difficulties, and need for further evaluation in pediatrics. Expert commentary: The new diagnostic tools may enhance diagnostic capacity in combination with traditional methods.

Acral manifestations of fungal infections

Fungal infections, which are named according to the body site involved, can affect any skin area, the fingernails, or the toenails. Numerous fungal agents are responsible for both superficial and deep fungal diseases. Dermatophytes and Candida spp are the most common causative organisms on the surface of the hands, feet, and nails of patients with superficial fungal diseases; however, although deep fungal infections of the skin are less common compared with superficial fungal diseases, their incidence is increasing worldwide due to cross-border travel. Most superficial fungal diseases are diagnosed clinically, but sometimes direct microscopic examination with potassium hydroxide and fungal culture may be necessary for diagnosis, especially in patients suspected of having tinea incognito. In cases of superficial fungal infections except for onychomycosis and tinea incognito, topical treatments are usually sufficient and effective, but systemic treatments may be required in recalcitrant cases. Deep fungal diseases may resemble each other clinically; therefore, the organism must be identified with laboratory methods and should be treated for a long period. We review the most important clinical, diagnostic, and therapeutic aspects of fungal diseases. This paper covers fungal problems encountered both in hospitals and in general practice.