Candida albicans causes brain regional invasion and necrosis, and activation of microglia during lethal neonatal neurocandidiasis

Neurocandidiasis is a fungal infection that primarily affects neonates, which is associated with 70% case fatality rates, while pediatric patients who survive infection often have long-term neurological sequelae, making it a clinical requirement to understand the pathogenesis of neonatal neurocandidiasis. Currently, the brain regions to Candida albicans invasion during the neonatal period are not characterized. In this study, 0-day-old mice were infected with C. albicans intravenously to determine dissemination and invasion into the brain at different times post-infection by fungal burden assay and histopathological analysis, additionally cellular death and microglial activation were evaluated by flow cytometry. The results evidenced the dissemination of C. albicans within the first hour of infection in the brain. The meninges were the initial site of invasion during the first 6 hours post infection and then filamentous structures into the brain parenchyma increases during infection, the anatomic regions most susceptible to invasion being the cerebral cortex, thalamus, hypothalamus, midbrain, pons, and medulla oblongata. Furthermore, C. albicans invasion of brain tissue results in cell necrosis and activation of microglia as a consequence of fungal invasion.

S6.2d Dermatophytosis due to Trichophyton erinacei caused by contact with African hedgehogs as family pets

S6.2 Resurgence of dermatophytic infections, September 22, 2022, 4:45 PM - 6:15 PM

 

Objective

To present a series of cases of various types of dermatophytosis caused by Trichophyton erinacei, caused by contact with African hedgehogs.

Methods

Patients with clinical suspicion of ringworm caused by T. erinacei were included in the study. Each patient underwent a mycological study, with direct examinations (KOH), cultures in Sabouraud dextrose agar medium with and without antibiotics. With the cultures obtained, molecular identification was made using the PCR technique and Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) proteomics. Once confirmed, the patients were given treatment and follow-up. When the pets (hedgehogs) were accessible, they were cultured with a cytobrush and the quills removed.

Results

In a period of 3.5 years, 16 verified cases were incorporated, 13 were females (72%) and 3 males (18%), the average age was 18.2 years, with the smallest case being 8 years old and the oldest 45 years old. The tineas manifested as follows: tinea manus 11 cases (68.7%); 2 respective cases of tinea corporis and tinea capitis (18.1 respectively) and one case of Majocchi's granuloma. The average evolution was 1.5 months with the case older than 3 months and the younger 15 days. All cases were given terbinafine at variable times and doses (according to weight and age) and clinical and mycological cure was obtained.

Discussion

Tineas can have epidemiological changes that are favored by a variety of factors, in general, pet ringworms are due to common domestic animals such as dogs and cats. Due to changing fashions, children and adolescents in recent years have changed pets such as hamsters, and recently hedgehogs, especially African variety (Atelerix albiventris) the latter may have T. erinacei as part of their skin microbiota, a similar dermatophyte or that was part of the T. mentagrophyes complex, in general of low virulence, however, its antigenic variants are little recognized by humans, which makes them present in a very inflammatory form, particularly in the hands, due to the handling of the animal, as well as the deeper inoculation (in the dermis) by the spikes left by the inoculum. So, they can generate deep tineas such as Majocchi's granuloma. In general, they respond well to systemic antifungals such as terbinafine and itraconazole, and sometimes the use of topical or systemic steroids is necessary.

Conclusions

This series of cases is a good example of how a change of habits when having pets can introduce new etiological agents that are poorly recognized antigenically, which give rise to more inflammatory and sometimes profound tineas.

Early production of proinflammatory cytokines in response to Scedosporium apiospermum during murine pulmonary infection

Scedosporium apiospermum is an opportunistic pathogen that can cause pulmonary infections in both immunosuppressive and immunocompetent patients. Cytokines are molecules that mediate the immune response to promote or eliminate fungal infections. In this work, we evaluated the cytokines profile in the lung and serum of mice infected with Scedosporium apiospermum. We found early production of IL-6, IL-1β and TNF-α cytokines in the lung of infected mice during the first 5 days of infection. We suggest that release of pro-inflammatory cytokines could play a role in the control of fungal invasion.

Dissemination of Candida auris to deep organs in neonatal murine invasive candidiasis

Candida auris is an emerging multidrug resistant fungal pathogen, which represents a major challenge for newborns systemic infections worldwide. Management of C. auris infections is complicated due to its intrinsic antifungal resistance and the limited information available on its pathogenesis, particularly during neonatal period. In this study, we developed a murine model of C. auris neonatal invasive infection. C. auris dissemination was evaluated by fungal burden and histopathological analysis of lung, brain, liver, kidney, and spleen at different time intervals. We found fungal cells in all the analyzed tissues, neonatal liver and brain were the most susceptible tissues to fungal invasion. This model will help to better understand pathogenesis mechanisms and facilitate strategies for control and prevention of C. auris infections in newborns.

Distinct innate immune responses between sublethal and lethal models of disseminated candidiasis in newborn BALB/c mice

Invasive candidiasis is associated with a high incidence and mortality rates in infants, especially in preterm newborns. The immunopathogenesis of the mycosis during the neonatal period is poorly understood. Although several in vivo models exist to study invasive candidiasis, the majority of studies employ distinct routes of infection and use 2 to 6 day-old mice that could be less comparable in studying candidiasis in preterm infants. In this study, by using 0-days-old mice we developed a new neonatal murine model of intravenous Candida albicans infection. Using different inoculums of Candida albicans we evaluated survival, dissemination of the fungus, frequency of CD45+ cells, and cytokine production in the liver, brain, and kidneys of newborn and adult BALB/c mice. Unexpectedly, the newborn mice infected with a low inoculum (1×105 cfu per mouse) of Candida albicans survive to the infection. Compared to adult mice, the liver and brain of newborn animals had the greatest fungal burden, fungal invasion and leukocyte infiltrate. A moderate production of TNFα, IL-1β, IL-6 and IFNγ was detected in tissues of newborn mice infected with a non-lethal inoculum of Candida albicans. In contrast, overproduction of TNFα, IL-1β, IL-6 and IL-10 was determined when injecting with a lethal inoculum. In agreement, flow cytometry of brain and liver showed an inoculum-dependent CD45+ leukocyte infiltration in newborn mice infected with Candida albicans. Overall, our data shows that Candida albicans infection in newborn mice affects mainly the brain and liver and a 2-fold increase of the inoculum rapidly becomes lethal probably due to massive fungal invasion and exacerbated CD45+ leukocyte infiltrate and cytokine production. This study is the first analysis of innate immune responses in different tissues during early neonatal disseminated candidiasis.

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.

[Evaluation of MALDI-TOF MS for the identification of opportunistic pathogenic yeasts of clinical samples]

MALDI-TOF MS mass spectrometry is a rapid and straightforward technique to identify microorganisms by protein analysis. The study was performed in 304 yeast isolates from superficial and deep mycoses, in order to compare three methods: conventional (biochemical and morphological), MALDI-TOF MS, and polymerase chain reaction (PCR, reference). We included 24 species with predominance of Candida spp and Cryptococcus spp. The identification by conventional methods was 258/304 strains, while by MALDI-TOF MS was: 277/304 strains (84.8% versus 91.2%, P = not significant). The Kappa coefficient comparing MALDI-TOF-MS with PCR reported excellent concordance (0.99). The sensitivity and specificity of MALDI-TOF MS for the diagnosis of opportunistic pathogenic yeasts of clinical samples were 94.6% and 99% respectively. MALDI-TOF MS is a simple, fast and reliable tool for pathogenic yeasts.

[Auricular sporotrichosis. Atypical case report simulating bacterial cellulitis]

Sporotrichosis is the most common subcutaneous or implantation mycosis in Mexico. The case of a preauricular cutaneous-fixed sporotrichosis simulating atypical bacterial cellulitis is reported in an elderly patient with no history of trauma. The biopsy showed a suppurative granuloma with scarce yeast. Sporothrix schenckii was identified in the culture and confirmed by molecular biology. She was treated with itraconazole and a clinical and mycological cure was obtained. The case of atypical presentation is presented, coming from a semi-arid zone with extreme weather.