Rare Neonatal Fungal Infection: Trichophyton Rubrum as a Cause of Dermatophytosis

Dermatophytes are fungi that infect keratin-rich tissues, with Tinea corporis, often caused by Trichophyton rubrum, affecting exposed skin. Although rare, systemic fungal infections in neonates pose high risks. The incidence of neonatal fungal infections appears to be increasing worldwide, with preterm infants being the most affected age group. A preterm neonate (born at 26 weeks + 6 days) with a birth weight of 970 g, inpatient at the neonatal intensive care unit (NICU) since birth, presented at day 25 of life with annular plaques with peripheral erythema, scaling and central clearing, located at the face, arm and dorsal region (Figure 1). She required positive pressure ventilation from the second day of life due to hyaline membrane disease and developed late neonatal sepsis, completing a 10-day course of antibiotic treatment with vancomycin by day 16. However, she was otherwise systemically well, with negative infection markers at the time that skin changes appeared. The mother had some minor lesions in her chest and had been practising skin-to-skin contact with the neonate. The mother, father and grandmother were treated with oral fluconazole. The domestic animals (2 cats) were taken to the veterinarian and had no skin lesions. After evaluation by a dermatology specialist, skin samples were collected with cellophane tape and for chicago sky blue stain and potassium hydroxide wet mount. Direct microscopy revealed the presence of septate hyphae (Figure 2). Empirical treatment with topical ketoconazole twice daily was started. Trichophyton rubrum was later identified in the fungal culture, confirming the diagnosis of tinea corporis by this agent. Complete resolution of the rash was observed within 1 week and the patient completed 21 days of topical treatment. Dermatophytes are fungi widespread globally, being the primary cause of fungal infections of the epidermis and other keratin-containing tissues, such as the hair and nails. Tinea corporis is a type of dermatophytosis that affects the epidermal layer of the skin, typically in exposed areas like the trunk, arms and legs. The most frequent causal agent for all ages is Trichophyton rubrum [1]. In the neonate, systemic fungal infections are uncommon but can result in high mortality and morbidity. To date, only 5 cases of tinea corporis by Tricophyton rubrum have been reported in neonates [2-6]. In this population, fungal infections can present unique challenges due to their delicate and developing immune systems and skin barrier [7]. In this age group, Tricophyton rubrum infections can manifest differently and may require specialised care and attention. Atypical presentations such as vesicles [2], pustules, and nodules [5, 6] have been described. Moreover, ring-shaped lesions and scaling on the skin can be indicative, but due to similarities with other dermatological conditions, a definitive diagnosis often requires laboratory testing, such as microscopic examination of skin scrapings or fungal cultures. Treatment usually consists of topical antifungal agents, such as ketoconazole, which effectively eliminate the infection [8]. In 3 out of the 5 previously reported cases [2, 5, 6], and despite no systemic symptoms being reported, intravenous antimycotics were also used, probably due to the larger number and wider distribution of skin lesions. One other aspect to consider is the mode of transmission. Neonates can acquire Trichophyton rubrum infection through contact with infected individuals (like caregivers) or contaminated objects. In a neonatal care setting, to prevent transmission, special attention must be given to maintaining a clean environment and monitoring for signs of infection to protect vulnerable infants [9]. Notably, in all 5 previously reported cases, the neonates were inpatients at the NICU or had been recently discharged when skin lesions first appeared; cross-infection of other patients was not recorded. Regarding sample collection, the traditional method of collecting skin scrapings by using the blunt side of a scalpel can be too abrasive against a newborn's fragile skin. Therefore, the use of cellophane tape arises as a safer alternative for this age group [10]. In summary, tinea corporis by Trichophyton rubrum is an extremely rare infection in neonates, with only 5 cases reported to date, and this age group requires specific considerations in terms of diagnosis, treatment, and prevention of transmission. In this particular case, despite being a preterm neonate with extremely low birth weight, the diagnosis was made quickly and treatment was promptly started, measures that were essential to prevent systemic involvement and resulted in an excellent response to therapy. The authors declare that the procedures were followed according to the regulations established by the Clinical Research and Ethics Committee and to the Helsinki Declaration of the World Medical Association updated in 2013. Written informed consent was obtained from the patient's legal guardian for publication of this case report and any accompanying images. The authors ensured that patient anonymity was maintained by omitting any identifying details in the report. Consent was obtained from the patient's mother, as the patient was under 18 years of age. The authors declare no conflicts of interest.