Superficial fungal infections of the skin, hair, and nails—collectively known as dermatomycoses—are among the most common infectious diseases on the planet, affecting an estimated 20 to 25 percent of the global human and animal population, with prevalence climbing even higher in tropical and subtropical climates. For decades, the public and clinical imagination has been dominated by a single cast of villains: the dermatophytes, a specialized group of fungi adapted to invade keratinized tissue. A new study from northern Iran now serves as a pointed reminder that this picture is dangerously incomplete. Researchers investigating patients with suspected non-dermatophyte skin infections in the city of Babol have uncovered a strikingly diverse array of yeasts and molds behind lesions that look, to the naked eye, almost indistinguishable from classic ringworm—findings that underscore why molecular diagnostics are becoming indispensable in modern medical mycology.
The research team, working through dermatology clinics affiliated with the Diagnostic Center of Skin Diseases in Babol, recruited patients over the course of one year whose clinical presentations suggested acute fungal skin infection but whose cultures did not grow dermatophytes. All confirmed dermatophyte cultures were deliberately excluded, sharpening the study’s focus on the neglected remainder of the fungal world. In total, 25 patients were enrolled, each of whom provided written informed consent under an ethics approval from Babol University of Medical Sciences. Before sampling, instruments were disinfected with ethanol and heat-sterilized, and the patients’ skin and nails were swabbed with alcohol to minimize contamination, after which skin and nail scrapings were collected under sterile conditions for laboratory analysis.
The diagnostic pipeline began with the classical tools of medical mycology. Skin scrapings were examined directly under the microscope after treatment with 10 percent potassium hydroxide, a reagent that dissolves keratin and reveals fungal elements, while nail samples required a stronger 30 percent concentration. Under magnification, the preparations revealed the telltale fingerprints of invasion: septate hyphae threading through skin cells, and in some nail specimens, yeast cells, germ tubes, and pseudohyphae. Samples were then inoculated onto Sabouraud Dextrose Agar supplemented with chloramphenicol to suppress bacteria, and in parallel onto the same medium with the addition of cycloheximide, which inhibits many saprophytic fungi. Plates were incubated at 28 degrees Celsius for up to four weeks and inspected daily as colonies emerged, with each isolate characterized by colony color, texture, shape, margin, and growth rate.
Morphology alone, however, proved insufficient for definitive species identification—a limitation that lies at the heart of the study’s message. The researchers therefore turned to slide culture techniques on Potato Dextrose Agar to examine spore-producing structures under lactophenol aniline blue staining, and then took the decisive extra step of molecular characterization. Fungal DNA was extracted using a phenol-chloroform method, and the internal transcribed spacer region—spanning ITS1, the 5.8S ribosomal DNA, and ITS4—was amplified by polymerase chain reaction with standard primers. The resulting PCR products were verified on agarose gels, purified, sequenced, aligned, and deposited in GenBank under accession numbers before being compared against reference strain databases, with similarity thresholds above 99 percent accepted for species-level assignment.
The demographic profile of the 25 patients revealed a pronounced female predominance: 72 percent of cases were women, compared with 28 percent men. Ages ranged from 26 to 82 years, with a mean of 52.2 years and a median of 52, indicating that these infections do not confine themselves to any single life stage. The researchers speculate that hormonal influences, differences in skin physiology, hygiene practices, and exposure to cosmetics or skincare products that can create microenvironments favorable to fungal overgrowth may contribute to the sex disparity, though they caution that larger studies will be needed to disentangle these factors.
Clinically, the infections were as varied as the fungi behind them. Itching was the dominant complaint, present in 84 percent of patients, followed by erythema in 64 percent and scaling in 60 percent. The feet, nails, and groin were the most frequently affected sites, each involved in four cases, while other lesions appeared on the axillae, forearms, nose, hands, knees, buttocks, chest folds, and genital skin. The duration of symptoms ranged remarkably widely—from as little as fifteen days to as long as fifteen years—with a mean of about sixteen months but a median of only six, reflecting a mix of acute presentations and long-neglected chronic disease. Several patients reported relatives with similar symptoms, hinting at familial transmission or shared environmental exposure, and some had regularly used public gyms and swimming pools, environments well known for facilitating fungal spread.
The mycological results drove home just how crowded the field of potential skin pathogens has become. Candida albicans was the most frequent isolate, recovered from four patients, but it was only the beginning. The team also identified Candida parapsilosis, Candida catenulata, Cutaneotrichosporon dermatis, Nakaseomyces glabratus, Rhodotorula mucilaginosa, Rhodotorula macerans, Sporobolomyces roseus, Bullera alba, and Trichosporon asahii among the yeasts, alongside molds including Epicoccum nigrum, Sarocladium strictum, Aspergillus phoenicis, and Penicillium chrysogenum. Many of these organisms are better known as environmental saprophytes—residents of soil, decaying vegetation, and even food—and several, including the carotenoid-pigmented Rhodotorula species and the basidiomycetous yeasts Sporobolomyces and Bullera, are rarely considered primary agents of skin disease.
The presence of such organisms in genuine lesions rather than as casual contaminants raises important questions about opportunism and host vulnerability. Opportunistic fungi typically establish infection only when they accidentally breach injured skin or when host defenses are weakened, and several patients in the cohort carried conditions consistent with that model, including type 2 diabetes, hypertension, rheumatoid arthritis, hypothyroidism, and a history of coronary artery bypass grafting. Antibiotic administration, immunosuppression, and disruptions of the normal skin microbiome are all recognized to elevate the risk of cutaneous candidiasis, and analogous mechanisms may underlie infections caused by the more obscure molds and basidiomycetous yeasts recovered here.
What makes this fungal diversity more than a taxonomic curiosity is its direct bearing on treatment. Infections caused by yeasts and molds often present with clinical features that closely mimic dermatophyte infections—and, notably, lesions produced by filamentous fungi are nearly impossible to tell apart from those produced by yeasts, and even different yeast genera produce essentially identical pictures. A clinician treating on visual impression alone may reach for an antifungal agent optimized for dermatophytes while the actual culprit, a Candida species or an Aspergillus relative, responds poorly or not at all. Distinct fungal species carry distinct antifungal susceptibility profiles, and inaccurate identification paired with the wrong drug can produce suboptimal responses, recurrent infection, chronic disease, prolonged suffering, and escalating treatment costs.
Even the laboratory’s traditional toolkit has blind spots. Many yeasts form colonies so morphologically similar in culture that they cannot be distinguished on macroscopic appearance, and sometimes not even on basic microscopy; certain molds display the same problem. This is precisely where DNA sequencing changes the game. By reading the genetic barcode of the fungal isolate, molecular methods can assign a species identity with precision even when culture and morphology are misleading. The study’s authors argue, on the basis of the enhanced sensitivity and specificity demonstrated for molecular detection across multiple investigations, that the most reliable diagnostic strategy combines direct microscopy, culture, and PCR-based identification rather than relying on any single technique.
The Babol findings arrive amid growing international evidence that the epidemiology of superficial fungal disease is shifting. The frequency and distribution of causative agents vary significantly with geography, migration patterns, climate, socioeconomic status, lifestyle, and cultural practices, and surveys from Ethiopia to Poland to Hangzhou, China, have documented non-dermatophyte molds increasingly dominating some case series, particularly in onychomycosis. Against this backdrop, a single-center study of 25 patients might seem modest, and the researchers themselves acknowledge that the constrained sample size limits generalizability, calling for larger multicenter investigations to map the epidemiology and etiology of non-dermatophyte dermatomycoses more comprehensively.
Yet the central conclusion stands on firm ground regardless of sample size: non-dermatophyte cutaneous mycoses are real, diverse, and diagnostically treacherous, and even experienced microscopists and mycologists must guard against dismissing unusual isolates as colonization or contamination. The study’s authors emphasize that raising clinician awareness of the wide spectrum of possible pathogens—and ensuring access to precise mycological diagnosis, including molecular identification where conventional methods fall short—is vital for effective patient treatment. As sequencing technology becomes faster and more affordable, the era in which a fungal skin infection could be treated on appearance alone is drawing to a close, replaced by a more exacting but ultimately far more effective paradigm: identify the organism first, then choose the weapon.
Subject of Research: Molecular identification of non-dermatophyte yeasts and molds causing dermatomycosis in patients referred to dermatology clinics in Babol, Iran
Subject of Research: Biology
Article Title: Dermatomycosis Caused by Non-Dermatophyte Agents; Diagnosis Based on Molecular Identification
Article References: Ranjbar Golafshani, F. Z., Akhondzadeh, A., Dastbaz Momtaz, A., Aryanian, Z., Kermani, F., Ghaffari Lashkenari, E., & Mahdavi Omran, S. (2026). Dermatomycosis Caused by Non‐Dermatophyte Agents; Diagnosis Based on Molecular Identification. MicrobiologyOpen, 15(3), Article e70341. https://doi.org/10.1002/mbo3.70341
Image Credits: AI Generated
DOI: 10.1002/mbo3.70341
Keywords: dermatomycosis, non-dermatophyte fungi, Candida albicans, ITS sequencing, molecular diagnostics, superficial fungal infection, Rhodotorula, opportunistic pathogens, antifungal susceptibility, potassium hydroxide microscopy, fungal culture, Babol
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Roger Howard. (September 7, 2026). Molecular Diagnosis of Dermatomycosis Caused by Non-Dermatophyte Fungi. Scienmag. https://scienmag.com/molecular-diagnosis-of-dermatomycosis-caused-by-non-dermatophyte-fungi/
Roger Howard. “Molecular Diagnosis of Dermatomycosis Caused by Non-Dermatophyte Fungi.” Scienmag, 7 September 2026, https://scienmag.com/molecular-diagnosis-of-dermatomycosis-caused-by-non-dermatophyte-fungi/. Accessed 7 September 2026.
Roger Howard. “Molecular Diagnosis of Dermatomycosis Caused by Non-Dermatophyte Fungi.” Scienmag. September 7, 2026. https://scienmag.com/molecular-diagnosis-of-dermatomycosis-caused-by-non-dermatophyte-fungi/
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