Methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus produce antimicrobial substances against members of the skin microbiota in children with atopic dermatitis.

Coagulase-negative Staphylococcus (CoNS) species inhibiting Staphylococcus aureus has been described in the skin of atopic dermatitis (AD) patients. This study evaluated whether Staphylococcus spp. from the skin and nares of AD and non-AD children produced antimicrobial substances (AMS). AMS production was screened by an overlay method and tested against NaOH, proteases and 30 indicator strains. Clonality was assessed by pulsed-field gel electrophoresis. Proteinaceous AMS-producers were investigated for autoimmunity by the overlay method and presence of bacteriocin genes by polymerase chain reaction. Two AMS-producers had their genome screened for AMS genes. A methicillin-resistant S. aureus (MRSA) produced proteinaceous AMS that inhibited 51.7% of the staphylococcal indicator strains, and it was active against 60% of the colonies selected from the AD child where it was isolated. On the other hand, 57 (8.8%) CoNS from the nares and skin of AD and non-AD children, most of them S. epidermidis (45.6%), reduced the growth of S. aureus and other CoNS species. Bacteriocin-related genes were detected in the genomes of AMS-producers. AMS production by CoNS inhibited S. aureus and other skin microbiota species from children with AD. Furthermore, an MRSA colonizing a child with AD produced AMS, reinforcing its contribution to dysbiosis and disease severity.

Bacteria from the skin of amphibians promote growth of Arabidopsis thaliana and Solanum lycopersicum by modifying hormone-related transcriptome response.

Plants and microorganisms establish beneficial associations that can improve their development and growth. Recently, it has been demonstrated that bacteria isolated from the skin of amphibians can contribute to plant growth and defense. However, the molecular mechanisms involved in the beneficial effect for the host are still unclear. In this work, we explored whether bacteria isolated from three tropical frogs species can contribute to plant growth. After a wide screening, we identified three bacterial strains with high biostimulant potential, capable of modifying the root structure of Arabidopsis thaliana plants. In addition, applying individual bacterial cultures to Solanum lycopersicum plants induced an increase in their growth. To understand the effect that these microorganisms have over the host plant, we analysed the transcriptomic profile of A. thaliana during the interaction with the C32I bacterium, demonstrating that the presence of the bacteria elicits a transcriptional response associated to plant hormone biosynthesis. Our results show that amphibian skin bacteria can function as biostimulants to improve agricultural crops growth and development by modifying the plant transcriptomic responses.

Amphibian skin bacteria display antifungal activity and induce plant defense mechanisms against Botrytis cinerea.

Botrytis cinerea is the causal agent of gray mold, which affects a wide variety of plant species. Chemical agents have been used to prevent the disease caused by this pathogenic fungus. However, their toxicity and reduced efficacy have encouraged the development of new biological control alternatives. Recent studies have shown that bacteria isolated from amphibian skin display antifungal activity against plant pathogens. However, the mechanisms by which these bacteria act to reduce the effects of B. cinerea are still unclear. From a diverse collection of amphibian skin bacteria, three proved effective in inhibiting the development of B. cinerea under in vitro conditions. Additionally, the individual application of each bacterium on the model plant Arabidopsis thaliana, Solanum lycopersicum and post-harvest blueberries significantly reduced the disease caused by B. cinerea. To understand the effect of bacteria on the host plant, we analyzed the transcriptomic profile of A. thaliana in the presence of the bacterium C32I and the fungus B. cinerea, revealing transcriptional regulation of defense-related hormonal pathways. Our study shows that bacteria from the amphibian skin can counteract the activity of B. cinerea by regulating the plant transcriptional responses.

Microbe Interactions within the Skin Microbiome.

The skin is the largest human organ and is responsible for many important functions, such as temperature regulation, water transport, and protection from external insults. It is colonized by several microorganisms that interact with each other and with the host, shaping the microbial structure and community dynamics. Through these interactions, the skin microbiota can inhibit pathogens through several mechanisms such as the production of bacteriocins, proteases, phenol soluble modulins (PSMs), and fermentation. Furthermore, these commensals can produce molecules with antivirulence activity, reducing the potential of these pathogens to adhere to and invade human tissues. Microorganisms of the skin microbiota are also able to sense molecules from the environment and shape their behavior in response to these signals through the modulation of gene expression. Additionally, microbiota-derived compounds can affect pathogen gene expression, including the expression of virulence determinants. Although most studies related to microbial interactions in the skin have been directed towards elucidating competition mechanisms, microorganisms can also use the products of other species to their benefit. In this review, we will discuss several mechanisms through which microorganisms interact in the skin and the biotechnological applications of products originating from the skin microbiota that have already been reported in the literature.

Skin Microbial Community Associated to Strawberry Disease in Farmed Rainbow Trout (Oncorhynchus mykiss Walbaum, 1792).

Aquaculture plays a crucial role in addressing the growing global demand for food. However, diseases associated with intensive aquaculture practices, especially those affecting the skin, can present significant challenges to both fish health and the industry as a whole. Strawberry disease (SD), also known as red-mark syndrome, is a persistent and non-lethal skin condition observed in Rainbow Trout (Oncorhynchus mykiss) in the United States and various European countries. SD is a nonlethal skin condition of an unclear etiology that affects rainbow trout reared in freshwater close to the harvest period. We used a RNA-based approach to examine active microbiota in the SD skin lesions and compared to non-injured skin. Our results, based on using 16S rRNA gene next-generation sequencing, showed that the skin microbiota was dominated by the phyla Firmicutes, Proteobacteria, and Actinobacteria. The comparisons of the skin microbiota between injured and non-injured samples showed differences in the alpha diversity (Fisher index) and beta diversity metrics (ANOSIM). At the genus level, both Pseudomonas and Candidatus Midichloria were highlighted as the most abundant taxa detected in samples obtained from fish affected with strawberry diseases. In contrast, the most abundant taxa in non-injured skin were Escherichia-Shigella, Streptococcus, and Pseudoalteromonas. In conclusion, our study on SD revealed distinct differences in the microbiota composition between skin lesions and non-injured skin. This is the first description of microbiota associated with SD-injured skin samples using an RNA approach.

First Report of Culturable Skin Bacteria in Melanophryniscus admirabilis (Admirable Redbelly Toad).

Melanophryniscus admirabilis is a small toad, critically endangered with a microendemic distribution in the Atlantic Forest in southern Brazil. The amphibian skin microbiome is considered one of the first lines of defense against pathogenic infections, such as Batrachochytrium dendrobatidis (Bd). The knowledge of skin amphibian microbiomes is important to numerous fields, including species conservation, detection, and quantification of environmental changes and stressors. In the present study, we investigated, for the first time, cultivable bacteria in the skin of wild M. admirabilis, and detected Bd fungus by nested polymerase chain reaction (PCR) technique. Skin swab samples were collected from 15 wild M. admirabilis, and the isolation of bacteria was performed by means of different culture strategies. A total of 62 bacterial isolates being Bacillus (n = 22; 34.48%), Citrobacter (n = 10; 16.13%), and Serratia (n = 12; 19.35%) were more frequently isolated genera. Interestingly, all skin samples tested were Bd negative. Some bacterial genera identified in our study might be acting in a synergic relationship and protecting them against the Bd fungus. In addition, these bacteria may play an essential role in maintaining this species in an environment modulated by anthropic actions. This first report of skin cultivable bacteria from M. admirabilis natural population improves our knowledge of skin amphibian microbiomes, contributing to a better understanding of their ecology and how this species has survived in an environment modulated by anthropic action.

The skin microbiota of the axolotl Ambystoma altamirani is highly influenced by metamorphosis and seasonality but not by pathogen infection.

BACKGROUND: Microbiomes have been increasingly recognized as major contributors to host health and survival. In amphibians, bacterial members of the skin microbiota protect their hosts by inhibiting the growth of the fungal pathogen Batrachochytrium dendrobatidis (Bd). Even though several studies describe the influence of biotic and abiotic factors over the skin microbiota, it remains unclear how these symbiotic bacterial communities vary across time and development. This is particularly relevant for species that undergo metamorphosis as it has been shown that host physiology and ecology drastically influence diversity of the skin microbiome. RESULTS: We found that the skin bacterial communities of the axolotl A. altamirani are largely influenced by the metamorphic status of the host and by seasonal variation of abiotic factors such as temperature, pH, dissolved oxygen and conductivity. Despite high Bd prevalence in these samples, the bacterial diversity of the skin microbiota did not differ between infected and non-infected axolotls, although relative abundance of particular bacteria were correlated with Bd infection intensity. CONCLUSIONS: Our work shows that metamorphosis is a crucial process that shapes skin bacterial communities and that axolotls under different developmental stages respond differently to environmental seasonal variations. Moreover, this study greatly contributes to a better understanding of the factors that shape amphibian skin microbiota, especially in a largely underexplored group like axolotls (Mexican Ambystoma species).

Drug resistance and phylogenetic grouping of bacteria isolated from visitors' hands in a secondary-care hospital.

INTRODUCTION: Dynamic movement in the hospital environment promotes the transmission of nosocomial pathogens and multidrug resistance mechanisms through the dissemination of organisms that carry genetic determinants. Healthcare workers play an important role in the spread of pathogens; however, the role of visitors in this environment is poorly understood. OBJECTIVE: This study aimed to molecularly identify and examine the antibiotic resistance of the palmar microbiota of patients' companions in a hospital waiting room. METHODOLOGY: Twenty-five palmar surface and interdigital space sample swabs were randomly collected and cultured on blood agar plates, and 19 colonies with different macro- and microscopic characteristics were isolated. The V4 and V6 hypervariable regions of the 16S rRNA gene from each isolate were amplified by PCR and sequenced. Maximum likelihood- and Bayesian inference-based phylogenetic analyses were performed to determine taxonomic relationships. Antibiotic resistance was evaluated by disk diffusion and broth microdilution. RESULTS: Among the isolates, 52.6% were related to Bacillus, 36.8% to Staphylococcus, 5.3% to Enterococcus and 5.3% to Atlantibacter. All of the isolates exhibited ampicillin and penicillin resistance, while 94.7% also exhibited dicloxacillin resistance. Staphylococcus aureus was resistant to penicillins but sensitive to the remaining drugs. Bacteria identified as Bacillus subtilis (MLM14B99), Bacillus pumilus (MLM23B07 and MLM25B06), Staphylococcus epidermidis (MLM24S31 and MLM29S04), and Enterococcus (MLM22E08) showed resistance to at least 46.7% of the antibiotics. CONCLUSIONS: To decrease the transmission of pathogenic bacteria with an antibiotic resistance profile, re-evaluation of hand cleaning measures and their application by people who visit hospital centres is needed.

Rosacea, poor sleep quality, and obstructive sleep apnea: A commentary on potential interconnected features.

Although rosacea is classically considered a skin disorder, recent evidence shows that it is emerging as a systemic disease. The classical symptoms of burning, intense erythema, and flushing could be related to several systemic and metabolic comorbidities. We highlight the role of sleep disturbance as a possible trigger for rosacea, which could be explained by the inflammatory and stressful conditions that can be produced by poor sleep. In particular, we call attention to obstructive sleep apnea (OSA), a common multisystemic sleep disorder; it could be linked with rosacea in the context of the metabolic syndrome, which in turn is frequently associated with OSA. Obstructive sleep apnea may be accompanied by autonomic system activation and catecholamine release, which can aggravate rosacea. Poor sleep, resulting from any underlying cause, can have a range of effects including immunological modulation and intrinsic cutaneous changes (such as the impairment of skin barrier defense and modifications in the skin microbiome) that may trigger rosacea. Further studies on this subject could provide more evidence on these relationships and help to improve the patients' quality of life and management of this uncomfortable and potentially severe skin condition.

Comparative Analysis of Skin Bacterial Diversity and Its Potential Antifungal Function Between Desert and Pine Forest Populations of Boreal Toads Anaxyrus boreas.

The skin microbiome in amphibians has gained a lot of attention as some of its members play a protective role against pathogens such as the fungus Batrachochytrium dendrobatidis (Bd). The composition of skin bacterial communities has been suggested as one of the factors explaining differences in susceptibility to Bd among amphibian species and populations. The boreal toad Anaxyrus boreas is known to be susceptible to Bd, and severe population declines in its southeastern range have been documented. However, throughout A. boreas distribution, populations present differences in susceptibility to Bd infections which may be associated with differences in skin microbial diversity. This study compared the skin bacterial diversity and Bd infection levels of A. boreas in one desert population and one pine forest population from Baja California, Mexico. We found that desert and pine forest toad populations exhibit differences in skin bacterial community structure but show similar Bd infection levels. Using a predictive method, we found that the abundance of bacteria with potential Bd-inhibitory properties differed between uninfected and infected individuals but not between populations. Our data suggest that several bacteria in the skin community may be offering protection from Bd infections in these A. boreas populations. This study provides foundational evidence for future studies seeking to understand the skin-microbial variation among boreal toads' populations and its relation with Bd susceptibility.

Composition and structure of the skin microbiota of rorquals off the Eastern South Pacific.

Recent advances in high-throughput sequencing have enabled the large-scale interrogation of microbiota in the most diverse environments, including host-associated microbiota. This has led to the recognition that the skin microbiota of rorquals is specific and structurally different from that of the ocean. This study reveals the skin microbiome of 85 wild individuals along the Chilean coast belonging to Megaptera novaeangliae, Balaenoptera musculus and Balaenoptera physalus. Alpha diversity analysis revealed significant differences in richness and phylogenetic diversity, particularly among humpback whales from different locations and between blue and humpback whales. Beta diversity was partially explained by host and location but only accounting for up to 17% of microbiota variability (adjusted VPA). Overall, we found that microbiota composition was dominated by bacterial genera such as Cardiobacter, Moraxella, Tenacibaculum, Stenotrophomonas, Flavobacteria and Pseudomonas. We also found that no ASVs were associated with the three rorqual species. Up to four ASVs were specific of a location, indicating a great variability in the microbiota. To the best of our knowledge, this is the first report on the composition and structure of the skin microbiota of whales off the coast of Chile, providing a foundational dataset to understand the microbiota's role in rorquals.

Skin microbiota as a therapeutic target for psoriasis treatment: Trends and perspectives.

Psoriasis is a chronic, immune-mediated disease that has a major negative impact on a patient's quality of life. Although several literature reviews indicate that skin microbiota may play an important role in the development and regulation of the immune and inflammatory response of psoriasis, few clinical studies are demonstrating the benefits of using pre-, pro- and synbiotics as a therapeutic alternative at the management of the disease. In this review, we showed the use of probiotic microorganisms that may contribute to skin homeostasis and compiled the clinical trials that demonstrate the effect of therapy with probiotics on patients with psoriasis, an important area for scientific exploration in dermatology and being the first review article to compile this information.

Novel repellents for the blood-sucking insects Rhodnius prolixus and Triatoma infestans, vectors of Chagas disease.

BACKGROUND: Studying the behavioral response of blood-sucking disease-vector insects to potentially repellent volatile compounds could shed light on the development of new control strategies. Volatiles released by human facial skin microbiota play different roles in the host-seeking behavior of triatomines. We assessed the repellency effect of such compounds of bacterial origin on Triatoma infestans and Rhodnius prolixus, two important vectors of Chagas disease in Latin America. METHODS: Using an exposure device, insects were presented to human odor alone (control) and in the presence of three individual test compounds (2-mercaptoethanol, dimethyl sulfide and 2-phenylethanol, the latter only tested in R. prolixus) and the gold-standard repellent NN-diethyl-3-methylbenzamide (DEET). We quantified the time the insects spent in the proximity of the host and determined if any of the compounds evaluated affected the behavior of the insects. RESULTS: We found volatiles that significantly reduced the time spent in the proximity of the host. These were 2-phenylethanol and 2-mercaptoethanol for R. prolixus, and dimethyl sulfide and 2-mercaptoethanol for T. infestans. Such an effect was also observed in both species when DEET was presented, although only at the higher doses tested. CONCLUSIONS: The new repellents modulated the behavior of two Chagas disease vectors belonging to two different triatomine tribes, and this was achieved using a dose up to three orders of magnitude lower than that needed to evoke the same effect with DEET. Future efforts in understanding the mechanism of action of repellent compounds such as 2-mercaptoethanol, as well as an assessment of their temporal and spatial repellent properties, could lead to the development of novel control strategies for these insect vectors, refractory to DEET.

Small Molecules Produced by Commensal Staphylococcus epidermidis Disrupt Formation of Biofilms by Staphylococcus aureus.

The microbiota influences host health through several mechanisms, including protecting it from pathogen colonization. Staphylococcus epidermidis is one of the most frequently found species in the skin microbiota, and its presence can limit the development of pathogens such as Staphylococcus aureusS. aureus causes diverse types of infections ranging from skin abscesses to bloodstream infections. Given the increasing prevalence of S. aureus drug-resistant strains, it is imperative to search for new strategies for treatment and prevention. Thus, we investigated the activity of molecules produced by a commensal S. epidermidis isolate against S. aureus biofilms. We showed that molecules present in S. epidermidis cell-free conditioned media (CFCM) caused a significant reduction in biofilm formation in most S. aureus clinical isolates, including all 4 agr types and agr-defective strains, without any impact on growth. S. epidermidis molecules also disrupted established S. aureus biofilms and reduced the antibiotic concentration required to eliminate them. Preliminary characterization of the active compound showed that its activity is resistant to heat, protease inhibitors, trypsin, proteinase K, and sodium periodate treatments, suggesting that it is not proteinaceous. RNA sequencing revealed that S. epidermidis-secreted molecules modulate the expression of hundreds of S. aureus genes, some of which are associated with biofilm production. Biofilm formation is one of the main virulence factors of S. aureus and has been associated with chronic infections and antimicrobial resistance. Therefore, molecules that can counteract this virulence factor may be promising alternatives as novel therapeutic agents to control S. aureus infections.IMPORTANCES. aureus is a leading agent of infections worldwide, and its main virulence characteristic is the ability to produce biofilms on surfaces such as medical devices. Biofilms are known to confer increased resistance to antimicrobials and to the host immune responses, requiring aggressive antibiotic treatment and removal of the infected surface. Here, we investigated a new source of antibiofilm compounds, the skin microbiome. Specifically, we found that a commensal strain of S. epidermidis produces molecules with antibiofilm activity, leading to a significant decrease of S. aureus biofilm formation and to a reduction of previously established biofilms. The molecules potentiated the activity of antibiotics and affected the expression of hundreds of S. aureus genes, including those associated with biofilm formation. Our research highlights the search for compounds that can aid us in the fight against S. aureus infections.

Novel repellents for the blood-sucking insects Rhodnius prolixus and Triatoma infestans, vectors of Chagas disease

Background: Studying the behavioral response of blood-sucking disease-vector insects to potentially repellent volatile compounds could shed light on the development of new control strategies. Volatiles released by human facial skin microbiota play diferent roles in the host-seeking behavior of triatomines. We assessed the repellency efect of such compounds of bacterial origin on Triatoma infestans and Rhodnius prolixus, two important vectors of Chagas disease in Latin America. Methods: Using an exposure device, insects were presented to human odor alone (control) and in the presence of three individual test compounds (2-mercaptoethanol, dimethyl sulfde and 2-phenylethanol, the latter only tested in R. prolixus) and the gold-standard repellent NN-diethyl-3-methylbenzamide (DEET). We quantifed the time the insects spent in the proximity of the host and determined if any of the compounds evaluated afected the behavior of the insects. Results: We found volatiles that signifcantly reduced the time spent in the proximity of the host. These were 2-phenylethanol and 2-mercaptoethanol for R. prolixus, and dimethyl sulfde and 2-mercaptoethanol for T. infestans. Such an efect was also observed in both species when DEET was presented, although only at the higher doses tested. Conclusions: The new repellents modulated the behavior of two Chagas disease vectors belonging to two diferent triatomine tribes, and this was achieved using a dose up to three orders of magnitude lower than that needed to evoke the same efect with DEET. Future eforts in understanding the mechanism of action of repellent compounds such as 2-mercaptoethanol, as well as an assessment of their temporal and spatial repellent properties, could lead to the development of novel control strategies for these insect vectors, refractory to DEET.

The Skin Microbiota of Eleutherodactylus Frogs: Effects of Host Ecology, Phylogeny, and Local Environment.

Amphibian skin microbiota has a potential protective role against diseases. However, the effects of environmental and host factors on symbiotic bacterial communities are not well understood. Caribbean frogs in the genus Eleutherodactylus represent a case of congeneric species that differ in ecological specialization by the process of adaptive radiation. For a small clade of Eleutherodactylus from Puerto Rico, we investigated the role of local environments, host species, and microhabitat in the composition of their skin microbiome. The potential congruence between microbial communities in hosts that are most closely related phylogenetically was also addressed. We hypothesized that the skin microbiota of Eleutherodactylus frogs would be mostly associated to microhabitat use, but also differ according to locality, and to a lesser extent to host species. To test this hypothesis, we swabbed the skin of a total of 98 adult individuals of seven Eleutherodactylus species distributed in two nearby localities in Puerto Rico, and sequenced the V4 region of the 16S rRNA gene. Results showed that locality had the greatest effect on determining skin bacterial communities of amphibian hosts, but this effect was stronger on the composition (based on presence/absence) than on its structure (based on sequence abundance). The most ecologically distinct host, E. cooki, and the generalist E. coqui presented, respectively, the most dissimilar and similar microbiota compared to other hosts. Host phylogeny showed a weak influence on skin microbiota. Results suggest that both local environment and ecological specialization are structuring the skin bacterial community in these Eleutherodactylus species, but that characteristics intrinsic to species may also render unique hosts the ability to maintain distinct microbiotas.

New concepts for transdermal delivery of oxygen based on catalase biochemical reactions studied by oxygen electrode amperometry.

The development of formulation concepts for improved skin tissue oxygenation, including methods for measuring oxygen (O2) transport across biological barriers, are important research topics with respect to all processes that are affected by the O2 concentration, such as radiation therapy in oncology treatments, wound healing, and the general health status of skin. In this work we approach this topic by a novel strategy based on the antioxidative enzyme catalase, which is naturally present in the skin organ where it enables conversion of the reactive oxygen species hydrogen peroxide (H2O2) into O2. We introduce various applications of the skin covered oxygen electrode (SCOE) as an in-vitro tool for studies of catalase activity and function. The SCOE is constructed by placing an excised skin membrane directly on an O2 electrode and the methodology is based on measurements of the electrical current generated by reduction of O2 as a function of time (i.e. chronoamperometry). The results confirm that a high amount of native catalase is present in the skin organ, even in the outermost stratum corneum (SC) barrier, and we conclude that excised pig skin (irrespective of freeze-thaw treatment) represents a valid model for ex vivo human skin for studying catalase function by the SCOE setup. The activity of native catalase in skin is sufficient to generate considerable amounts of O2 by conversion from H2O2 and proof-of-concept is presented for catalase-based transdermal O2 delivery from topical formulations containing H2O2. In addition, we show that this concept can be further improved by topical application of external catalase on the skin surface, which enables transdermal O2 delivery from 50 times lower concentrations of H2O2. These important results are promising for development of novel topical or transdermal formulations containing low and safe concentrations of H2O2 for skin tissue oxygenation. Further, our results indicate that the O2 production by catalase, derived from topically applied S. epidermidis (a simple model for skin microbiota) is relatively low as compared to the O2 produced by the catalase naturally present in skin. Still, the catalase activity derived from S. epidermidis is measurable. Taken together, this work illustrates the benefits and versatility of the SCOE as an in vitro skin research tool and introduces new and promising strategies for transdermal oxygen delivery, with simultaneous detoxification of H2O2, based on native or topically applied catalase.

Prodigiosin, Violacein, and Volatile Organic Compounds Produced by Widespread Cutaneous Bacteria of Amphibians Can Inhibit Two Batrachochytrium Fungal Pathogens.

Symbiotic bacteria can produce secondary metabolites and volatile compounds that contribute to amphibian skin defense. Some of these symbionts have been used as probiotics to treat or prevent the emerging disease chytridiomycosis. We examined 20 amphibian cutaneous bacteria for the production of prodigiosin or violacein, brightly colored defense compounds that pigment the bacteria and have characteristic spectroscopic properties making them readily detectable, and evaluated the antifungal activity of these compounds. We detected violacein from all six isolates of Janthinobacterium lividum on frogs from the USA, Switzerland, and on captive frogs originally from Panama. We detected prodigiosin from five isolates of Serratia plymuthica or S. marcescens, but not from four isolates of S. fonticola or S. liquefaciens. All J. lividum isolates produced violacein when visibly purple, while prodigiosin was only detected on visibly red Serratia isolates. When applied to cultures of chytrid fungi Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal), prodigiosin caused significant growth inhibition, with minimal inhibitory concentrations (MIC) of 10 and 50 µM, respectively. Violacein showed a MIC of 15 µM against both fungi and was slightly more active against Bsal than Bd at lower concentrations. Although neither violacein nor prodigiosin showed aerosol activity and is not considered a volatile organic compound (VOC), J. lividum and several Serratia isolates did produce antifungal VOCs. White Serratia isolates with undetectable prodigiosin levels could still inhibit Bd growth indicating additional antifungal compounds in their chemical arsenals. Similarly, J. lividum can produce antifungal compounds such as indole-3-carboxaldehyde in addition to violacein, and isolates are not always purple, or turn purple under certain growth conditions. When Serratia isolates were grown in the presence of cell-free supernatant (CFS) from the fungi, CFS from Bd inhibited growth of the prodigiosin-producing isolates, perhaps indicative of an evolutionary arms race; Bsal CFS did not inhibit bacterial growth. In contrast, growth of one J. lividum isolate was facilitated by CFS from both fungi. Isolates that grow and continue to produce antifungal compounds in the presence of pathogens may represent promising probiotics for amphibians infected or at risk of chytridiomycosis. In a global analysis, 89% of tested Serratia isolates and 82% of J. lividum isolates were capable of inhibiting Bd and these have been reported from anurans and caudates from five continents, indicating their widespread distribution and potential for host benefit.

Survey of Malassezia sp and dermatophytes in the cutaneous microbiome of free-ranging golden-headed lion tamarins (Leontopithecus chrysomelas - Kuhl, 1820).

BACKGROUND: Data about the presence of fungi on the cutaneous surface of wild animals are scarce. The aim of this study was to survey dermatophytes and Malassezia sp in the external ear canal and haircoat of Leontopithecus chrysomelas. METHODS: A total of 928 clinical samples were collected from 232 animals: For Malassezia screening 696 samples were studied, 464 of cerumen and 232 of haircoat; another 232 haircoat samples were studied for dermatophyte analysis. RESULTS: A geophilic dermatophyte, Microsporum cookie, was isolated from one young female. Lipodependent Malassezia was isolated from 76 animals and 87 clinical samples, 26 from the cerumen and 61 from the haircoat (statistically significant); there were no differences related to gender and age. CONCLUSIONS: Results suggested that lipodependent Malassezia is part of the skin microbiome of these animals. The prevalence of dermatophytes was too low and probably not relevant for the health of the studied population.