Effects of Leishmania major infection on the gut microbiome of resistant and susceptible mice.

Cutaneous leishmaniasis, a parasitic disease caused by Leishmania major, is a widely frequent form in humans. To explore the importance of the host gut microbiota and to investigate its changes during L. major infection, two different groups of mouse models were assessed. The microbiome of two parts of the host gut-ileum and colon-from infected and non-infected mice were characterised by sequencing of 16S rDNA using an Ion Torrent PGM platform. Microbiome analysis was performed to reveal changes related to the susceptibility and the genetics of mice strains in two different gut compartments and to compare the results between infected and non-infected mice. The results showed that Leishmania infection affects mainly the ileum microbiota, whereas the colon bacterial community was more stable. Different biomarkers were determined in the gut microbiota of infected resistant mice and infected susceptible mice using LEfSe analysis. Lactobacillaceae was associated with resistance in the colon microbiota of all resistant mice strains infected with L. major. Genes related to xenobiotic biodegradation and metabolism and amino acid metabolism were primarily enriched in the small intestine microbiome of resistant strains, while genes associated with carbohydrate metabolism and glycan biosynthesis and metabolism were most abundant in the gut microbiome of the infected susceptible mice. These results should improve our understanding of host-parasite interaction and provide important insights into the effect of leishmaniasis on the gut microbiota. Also, this study highlights the role of host genetic variation in shaping the diversity and composition of the gut microbiome. KEY POINTS: • Leishmaniasis may affect mainly the ileum microbiota while colon microbiota was more stable. • Biomarkers related with resistance or susceptibility were determined in the gut microbiota of mice. • Several pathways were predicted to be upregulated in the gut microbiota of resistant or susceptible mice.

Divergent allele advantage in the MHC and amphibian emerging infectious disease.

Genetic variation in the major histocompatibility complex (MHC) may be associated with resistance to the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). The pathogen originated in Asia, then spread worldwide, causing amphibian population declines and species extinctions. We compared the expressed MHC IIß1 alleles of a Bd-resistant species, Bufo gargarizans, from South Korea with those of a Bd-susceptible Australasian species, Litoria caerulea. We found at least six expressed MHC IIß1 loci in each of the two species. Amino acid diversity encoded by these MHC alleles was similar between species, but the genetic distance of those alleles known for potential broader pathogen-derived peptide binding was greater in the Bd-resistant species. In addition, we found a potentially rare allele in one resistant individual from the Bd-susceptible species. Deep next-generation sequencing recovered approximately triple the genetic resolution accessible from traditional cloning-based genotyping. Targeting the full MHC IIß1 enables us to better understand how host MHC may adapt to emerging infectious diseases.

Associations of the skin, oral and gut microbiome with aging, frailty and infection risk reservoirs in older adults.

Older adults represent a vulnerable population with elevated risk for numerous morbidities. To explore the association of the microbiome with aging and age-related susceptibilities including frailty and infectious disease risk, we conducted a longitudinal study of the skin, oral, and gut microbiota in 47 community- or skilled nursing facility-dwelling older adults vs. younger adults. We found that microbiome changes were not associated with chronological age so much as frailty: we identified prominent changes in microbiome features associated with susceptibility to pathogen colonization and disease risk, including diversity, stability, heterogeneity, and biogeographic determinism, which were moreover associated with a loss of Cutibacterium (C.) acnes in the skin microbiome. Strikingly, the skin microbiota were also the primary reservoir for antimicrobial resistance, clinically important pathobionts, and nosocomial strains, suggesting a potential role particularly for the skin microbiome in disease risk and dissemination of multidrug resistant pathogens.

Increased susceptibility of irradiated mice to Aspergillus fumigatus infection via NLRP3/GSDMD pathway in pulmonary bronchial epithelia.

BACKGROUND: Aspergillus fumigatus infection is difficult to diagnose clinically and can develop into invasive pulmonary aspergillosis, which has a high fatality rate. The incidence of Aspergillus fumigatus infection has increased die to widespread application of radiotherapy technology. However, knowledge regarding A. fumigatus infection following radiation exposure is limited, and the underlying mechanism remains unclear. In this study, we established a mouse model to explore the effect of radiation on A. fumigatus infection and the associated mechanisms. METHODS: In this study, a mouse model of A. fumigatus infection after radiation was established by irradiating with 5 Gy on the chest and instilling 5 × 107/ml Aspergillus fumigatus conidia into trachea after 24 h to explore the effect and study its function and mechanism. Mice were compared among the following groups: normal controls (CON), radiation only (RA), infection only (Af), and radiation + infection (RA + Af). Staining analyses were used to detect infection and damage in lung tissues. Changes in protein and mRNA levels of pyroptosis-related molecules were assessed by western blot analysis and quantitative reverse transcription polymerase chain reaction, respectively. Protein concentrations in the serum and alveolar lavage fluid were also measured. An immunofluorescence colocalization analysis was performed to confirm that NLRP3 inflammasomes activated pyroptosis. RESULTS: Radiation destroyed the pulmonary epithelial barrier and significantly increased the pulmonary fungal burden of A. fumigatus. The active end of caspase-1 and gasdermin D (GSDMD) were highly expressed even after infection. Release of interleukin-18 (IL-18) and interleukin-1ß (IL-1ß) provided further evidence of pyroptosis. NLRP3 knockout inhibited pyroptosis, which effectively attenuated damage to the pulmonary epithelial barrier and reduced the burden of A. fumigatus. CONCLUSIONS: Our findings indicated that the activation of NLRP3 inflammasomes following radiation exposure increased susceptibility to A. fumigatus infection. Due to pyroptosis in lung epithelial cells, it resulted in the destruction of the lung epithelial barrier and further damage to lung tissue. Moreover, we found that NLRP3 knockout effectively inhibited the pyroptosis and reducing susceptibility to A. fumigatus infection and further lung damage. Overall, our results suggest that NLRP3/GSDMD pathway mediated-pyroptosis in the lungs may be a key event in this process and provide new insights into the underlying mechanism of infection. Video abstract.

tRNA-derived fragments from wheat are potentially involved in susceptibility to Fusarium head blight.

BACKGROUND: Fusarium head blight (FHB) caused by Fusarium graminearum is a devastating fungal disease of wheat. The mechanism underlying F. graminearum-wheat interaction remains largely unknown. tRNA-derived fragments (tRFs) are RNase-dependent small RNAs derived from tRNAs, and they have not been reported in wheat yet, and whether tRFs are involved in wheat-F. graminearum interactions remains unknown. RESULTS: Herein, small RNAs from the spikelets inoculated with F. graminearum and mock from an FHB-susceptible variety Chinese Spring (CS) and an FHB-resistant variety Sumai3 (SM) were sequenced respectively. A total of 1249 putative tRFs were identified, in which 15 tRFs was CS-specific and 12 SM-specific. Compared with mock inoculation, 39 tRFs were significantly up-regulated across both wheat varieties after F. graminearum challenge and only nine tRFs were significantly down-regulated. tRFGlu, tRFLys and tRFThr were dramatically induced by F. graminearum infection, with significantly higher fold changes in CS than those in SM. The expression patterns of the three highly induced tRFs were further validated by stem-loop qRT-PCR. The accumulation of tRFs were closely related to ribonucleases T2 family members, which were induced by F. graminearum challenge. The tRFs' targets in host were predicted and were validated by RNA sequencing. CONCLUSION: Integrative analysis of the differentially expressed tRFs and their candidate targets indicated that tRFGlu, tRFLys and tRFThr might negatively regulate wheat resistance to FHB. Our results unvealed the potential roles of tRFs in wheat-F. graminearum interactions.

The gut microbiome in konzo.

Konzo, a distinct upper motor neuron disease associated with a cyanogenic diet and chronic malnutrition, predominately affects children and women of childbearing age in sub-Saharan Africa. While the exact biological mechanisms that cause this disease have largely remained elusive, host-genetics and environmental components such as the gut microbiome have been implicated. Using a large study population of 180 individuals from the Democratic Republic of the Congo, where konzo is most frequent, we investigate how the structure of the gut microbiome varied across geographical contexts, as well as provide the first insight into the gut flora of children affected with this debilitating disease using shotgun metagenomic sequencing. Our findings indicate that the gut microbiome structure is highly variable depending on region of sampling, but most interestingly, we identify unique enrichments of bacterial species and functional pathways that potentially modulate the susceptibility of konzo in prone regions of the Congo.

Pneumonia, Sinusitis, Influenza and Other Respiratory Illnesses in Acute Otitis Media-Prone Children.

BACKGROUND: Recurrent acute otitis media in the first years of life can be explained by immune dysfunction. Consequently, it would be expected that otitis-prone (OP) children would be more susceptible to other infectious diseases, especially respiratory infections, since a component of the immune problem involves nasopharyngeal innate immunity. DESIGN: Cohort study with prospective identification of all physician-diagnosed, medically attended respiratory illness visits in children 6 months to 5 years of age to determine the incidence of pneumonia, acute sinusitis, influenza and other bacterial and viral infections among OP compared with non-OP (NOP) children. Tympanocentesis to microbiologically confirm acute otitis media disease. RESULTS: Two hundred eighty-five children were studied. Thirty-nine met a standard definition of stringently defined OP (sOP) determined by tympanocentesis and 246 were NOP. sOP children had increased frequency of presumptive respiratory infections, pneumonia (6-fold higher, P < 0.001), sinusitis (2.1-fold higher, P = 0.026) and influenza (2.9-fold higher, P = 0.002), compared with NOP children. Demographic and risk factor covariate-adjusted fold difference between sOP and NOP children for all respiratory infection illness visits was 2.4-fold (P < 0.00001) at 6-18 months of age, 2.2-fold (P < 0.00001) at 18-30 months of age and at age and 2.4-fold (P = 0.035) higher at 30 to 42 months. For both sOP and NOP children, more frequent medically attended respiratory infection illness visits from 6-18 months of age predicted more frequent visits experienced from 18-60 months of age. CONCLUSIONS: Clinicians should be aware of a significant increased likelihood of bacterial and viral respiratory infection proneness among OP children.

Helminth-virus interactions: determinants of coinfection outcomes.

Viral infections are often studied in model mammalian organisms under specific pathogen-free conditions. However, in nature, coinfections are common, and infection with one organism can alter host susceptibility to infection with another. Helminth parasites share a long coevolutionary history with mammalian hosts and have shaped host physiology, metabolism, immunity, and the composition of the microbiome. Published studies suggest that helminth infection can either be beneficial or detrimental during viral infection. Here, we discuss coinfection studies in mouse models and use them to define key determinants that impact outcomes, including the type of antiviral immunity, the tissue tropism of both the helminth and the virus, and the timing of viral infection in relation to the helminth lifecycle. We also explore the current mechanistic understanding of how helminth-virus coinfection impacts host immunity and viral pathogenesis. While much attention has been placed on the impact of the gut bacterial microbiome on immunity to infection, we suggest that enteric helminths, as a part of the eukaryotic macrobiome, also represent an important modulator of disease pathogenesis and severity following virus infection.

Evaluation of pain susceptibility by taking blood pressure in patients with infections: A prospective comparative study.

ABSTRACT: Pain sensitization leading to polyalgia can be observed during infectious diseases. The blood pressure cuff-evoked pain threshold (BPCEPT) has been used in previous studies as a screening tool for fibromyalgia.We aimed to use the BPCEPT as a screening test for detecting pain sensitization in patients suffering from infectious diseases. We also investigated whether specific factors were associated with pain sensitization.We performed a prospective comparative study including all patients of our infectious diseases center in a 1-year period. We created a positive control group of patients suffering from fibromyalgia and a negative control group of "apparently healthy" patients consulting for vaccination.The blood pressure (BP) cuff was inflated until the patient signaled that they experienced pain, and this pressure value was noted.A total of 2355 patients were included. The positive control group had significantly lower values of the BPCEPT than all other groups. Among hospitalized patients with infectious diseases, a low BPCEPT was significantly associated with high temperature (P < .0001), older age (P = .002), being a woman (P = .004), high serum glutamic-oxaloacetic transaminase (P = .007), and high C reactive protein levels (P = .02). Moreover, in multivariate analysis, respiratory infection, meningitis, urinary tract infection, febrile neutropenia, and Q fever were independently associated with a low BPCEPT. A significant negative dynamic correlation between the BPCEPT and temperature was also observed (P < .001).We demonstrated for the first time in a large sample of patients that the BPCEPT method can be used to detect pain susceptibility. We observed a significant dynamic correlation between pain sensitization and temperature. Additionally, pain sensitization was associated with some diseases, suggesting that they trigger pain sensitivity.

Genetic variations of toll-like receptors: Impact on susceptibility, severity and prognosis of bacterial meningitis.

Bacterial meningitis (BM) is a serious infectious disease of the central nervous system，which is mainly caused by Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Group B Streptococcus and Listeria monocytogenes. Throughout the world, BM has become one of the most lethal diseases that commonly occurs in children. Toll like receptors (TLRs) are one of the most important immune defense lines in infectious diseases, and play an essential role in host defense. Accumulating evidence shows that genetic variations in TLRs are associated with host responses in BM. This review aims to summarize the role of different TLRs and their genetic variations in the susceptibility, severity and prognosis of BM and discuss the identified risk factors for better treatment and improvement of the course and outcome of BM.

Effect of COVID-19 precautions on the gut microbiota and nosocomial infections.

COVID-19 precautions decrease social connectedness. It has been proposed that these measures alter the gut microbiota, with potential clinical consequences. We tested this hypothesis in patients with acute myeloid leukemia (AML) receiving inpatient chemotherapy, a population with extensive exposure to the nosocomial setting and at high risk for infections. Hospitalized patients with AML contributed stool samples to a biorepository protocol that was initiated before COVID-19 and continued without change through the pandemic. Patient-, disease-, and treatment-related characteristics remained the same in the two eras and the only change in clinical care was the implementation of COVID-19 precautions in March 2020. The incidence of all-cause nosocomial infections during the pandemic was lower than in the pre-COVID-19 era. Multivariable analysis revealed an imprint of COVID-19 precautions in the gut microbiota as a viable mechanistic explanation. In conclusion, COVID-19 precautions alter the gut microbiota, thereby mediating pathogen susceptibility and nosocomial infections.

Genome-scale comparative analysis for host resistance against sea lice between Atlantic salmon and rainbow trout.

Sea lice (Caligus rogercresseyi) is an ectoparasite which causes major production losses in the salmon aquaculture industry worldwide. Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) are two of the most susceptible salmonid species to sea lice infestation. The objectives of this study were to: (1) identify genomic regions associated with resistance to Caligus rogercresseyi in Atlantic salmon and rainbow trout by performing single-step Genome-Wide Association studies (ssGWAS), and (2) identify candidate genes related to trait variation based on exploring orthologous genes within the associated regions across species. A total of 2626 Atlantic salmon and 2643 rainbow trout were challenged and genotyped with 50 K and 57 K SNP panels, respectively. We ran two independent ssGWAS for sea lice resistance on each species and identified 7 and 13 regions explaining more than 1% of the genetic variance for the trait, with the most important regions explaining 3% and 2.7% for Atlantic salmon and rainbow trout, respectively. We identified genes associated with immune response, cytoskeleton function, and cell migration when focusing on important genomic regions for each species. Moreover, we found 15 common orthogroups which were present in more than one associated genomic region, within- or between-species; however, only one orthogroup showed a clear potential biological relevance in the response against sea lice. For instance, dual-specificity protein phosphatase 10-like (dusp10) and dual-specificity protein phosphatase 8 (dusp8) were found in genomic regions associated with lice density in Atlantic salmon and rainbow trout, respectively. Dusp10 and dusp8 are modulators of the MAPK pathway and might be involved in the differences of the inflammation response between lice resistant and susceptible fish from both species. Our results provide further knowledge on candidate genes related to sea lice resistance and may help establish better control for sea lice in fish populations.

The Murine Neonatal Fc Receptor Is Required for Transport of Immunization-Induced C. difficile-Specific IgG to the Gut and Protection against Disease but Does Not Affect Disease Susceptibility.

The pathology associated with Clostridioides difficile disease is caused in large part by TcdB, an intracellular bacterial toxin that inactivates small GTPases. Despite C. difficile causing enteric disease, antitoxin IgG is a clear correlate of protection against infection-associated pathology. Immunization with TcdB-based immunogens or passive transfer of monoclonal antibodies specific for the TcdB carboxy-terminal domain (CTD) confers protection following C. difficile infection. Whether the mechanism by which circulating IgG is delivered to the gut depends on specific receptor-mediated transport or is solely reflective of infection-induced damage to the gut remains unclear. Here, we tested the hypothesis that neonatal Fc receptor (FcRn) is required for the delivery of systemic TcdB-specific IgG to the gut and protection against C. difficile-associated pathology. FcRn-expressing mice and FcRn-deficient littermates were immunized subcutaneously with Alhydrogel adjuvant-adsorbed CTD before challenge with live C. difficile spores. FcRn was required for the delivery of systemic TcdB-specific IgG to the gut and for vaccine-induced protection against C. difficile-associated disease. The lack of FcRn expression had minimal effects on the composition of the gut microbiome and did not affect susceptibility to C. difficile infection in nonimmunized mice. In further experiments, intraperitoneal injection of immune sera in FcRn-deficient mice led to the transport of protective IgG to the gut independently of infection, confirming a reported method of bypassing the FcRn. Our results reveal an FcRn-dependent mechanism by which systemic immunization-induced IgG protects the gut during enteric C. difficile infection. These findings may be beneficial for the targeting of C. difficile-specific IgG to the gut.

Dermal bacterial LPS-stimulation reduces susceptibility to intradermal Trypanosoma brucei infection.

Infections with Trypanosoma brucei sp. are established after the injection of metacyclic trypomastigotes into the skin dermis by the tsetse fly vector. The parasites then gain access to the local lymphatic vessels to infect the local draining lymph nodes and disseminate systemically via the bloodstream. Macrophages are considered to play an important role in host protection during the early stage of systemic trypanosome infections. Macrophages are abundant in the skin dermis, but relatively little is known of their impact on susceptibility to intradermal (ID) trypanosome infections. We show that although dermal injection of colony stimulating factor 1 (CSF1) increased the local abundance of macrophages in the skin, this did not affect susceptibility to ID T. brucei infection. However, bacterial LPS-stimulation in the dermis prior to ID trypanosome infection significantly reduced disease susceptibility. In vitro assays showed that LPS-stimulated macrophage-like RAW264.7 cells had enhanced cytotoxicity towards T. brucei, implying that dermal LPS-treatment may similarly enhance the ability of dermal macrophages to eliminate ID injected T. brucei parasites in the skin. A thorough understanding of the factors that reduce susceptibility to ID injected T. brucei infections may lead to the development of novel strategies to help reduce the transmission of African trypanosomes.

HIV susceptibility in women: The roles of genital inflammation, sexually transmitted infections and the genital microbiome.

Given that heterosexual transmission of HIV across the genital mucosa is the most common route of infection in women, an in-depth understanding of the biological mechanisms associated with HIV risk in the female genital tract (FGT) is essential for effective control of the epidemic. Genital pro-inflammatory cytokines are well-described biological co-factors to HIV risk. Increased levels of pro-inflammatory cytokines in the FGT have been associated with a 3-fold higher-risk of acquiring HIV, presumably through involvement in barrier compromise and the recruitment of highly activated HIV target cells to the site of initial viral infection and replication. Sexually transmitted infections (STIs) and bacterial vaginosis (BV) are suggested possible contributors to genital inflammation in the FGT, and this, coupled with the relationship between genital inflammation and HIV risk, underscores the importance of effective treatment of STI and BV in the promotion of women's health. In most low- and middle-income countries, STIs are treated syndromically, a practice providing rapid treatment without identifying the infection source. However, this approach has been associated with over-diagnosis and the overuse of drugs. Further, because many women with STIs are asymptomatic, syndromic management also fails to treat a vast proportion of infected women. Although several studies have explored the role of STIs and the vaginal microbiome on genital inflammation and HIV risk, the impact of STI and BV management on genital inflammation remains poorly understood. This review aimed to collate the evidence on how BV and STI management efforts affect genital inflammation and the genital microbiome in women.

A protein kinase-major sperm protein gene hijacked by a necrotrophic fungal pathogen triggers disease susceptibility in wheat.

Septoria nodorum blotch (SNB), a disease caused by the necrotrophic fungal pathogen Parastagonospora nodorum, is a threat to wheat (Triticum aestivum) production worldwide. Multiple inverse gene-for-gene interactions involving the recognition of necrotrophic effectors (NEs) by wheat sensitivity genes play major roles in causing SNB. One interaction involves the wheat gene Snn3 and the P. nodorum NE SnTox3. Here, we used a map-based strategy to clone the Snn3-D1 gene from Aegilops tauschii, the D-genome progenitor of common wheat. Snn3-D1 contained protein kinase and major sperm protein domains, both of which were essential for function as confirmed by mutagenesis. As opposed to other characterized interactions in this pathosystem, a compatible Snn3-D1-SnTox3 interaction was light-independent, and Snn3-D1 transcriptional expression was downregulated by light and upregulated by darkness. Snn3-D1 likely emerged in Ae. tauschii due to an approximately 218-kb insertion that occurred along the west bank of the Caspian Sea. The identification of this new class of NE sensitivity genes combined with the previously cloned sensitivity genes demonstrates that P. nodorum can take advantage of diverse host targets to trigger SNB susceptibility in wheat.

The contribution of gut bacterial metabolites in the human immune signaling pathway of non-communicable diseases.

The interaction disorder between gut microbiota and its host has been documented in different non-communicable diseases (NCDs) such as metabolic syndrome, neurodegenerative disease, and autoimmune disease. The majority of these altered interactions arise through metabolic cross-talk between gut microbiota and host immune system, inducing a low-grade chronic inflammation that characterizes all NCDs. In this review, we discuss the contribution of bacterial metabolites to immune signaling pathways involved in NCDs. We then review recent advances that aid to rationally design microbial therapeutics. A deeper understanding of these intersections between host and gut microbiota metabolism using metabolomics-based system biology platform promises to reveal the fundamental mechanisms that drive metabolic predispositions to disease and suggest new avenues to use microbial therapeutic opportunities for NCDs treatment and prevention. Abbreviations: NCDs: non-communicable disease, IBD: inflammatory bowel disease, IL: interleukin, T2D: type 2 diabetes, SCFAs: short-chain fatty acids, HDAC: histone deacetylases, GPCR: G-protein coupled receptors, 5-HT: 5-hydroxytryptamine receptor signaling, DCs: dendritic cells, IECs: intestinal epithelial cells, T-reg: T regulatory cell, NF-κB: nuclear factor κB, TNF-α: tumor necrosis factor alpha, Th: T helper cell, CNS: central nervous system, ECs: enterochromaffin cells, NSAIDs: non-steroidal anti-inflammatory drugs, AhR: aryl hydrocarbon receptor, IDO: indoleamine 2,3-dioxygenase, QUIN: quinolinic acid, PC: phosphatidylcholine, TMA: trimethylamine, TMAO: trimethylamine N-oxide, CVD: cardiovascular disease, NASH: nonalcoholic steatohepatitis, BAs: bile acids, FXR: farnesoid X receptor, CDCA: chenodeoxycholic acid, DCA: deoxycholic acid, LCA: lithocholic acid, UDCA: ursodeoxycholic acid, CB: cannabinoid receptor, COBRA: constraint-based reconstruction and analysis.

Immune System Efficiency in Cancer and the Microbiota Influence.

The immune system plays a critical role in preventing cancer development and progression. However, the complex network of cells and soluble factor that form the tumor microenvironment (TME) can dictate the differentiation of tumor-infiltrating leukocytes and shift the antitumor immune response into promoting tumor growth. With the advent of cancer immunotherapy, there has been a reinvigorated interest in defining how the TME shapes the antitumor immune response. This interest brought to light the microbiome as a novel player in shaping cancer immunosurveillance. Indeed, accumulating evidence now suggests that the microbiome may confer susceptibility or resistance to certain cancers and may influence response to therapeutics, particularly immune checkpoint inhibitors. As we move forward into the age of precision medicine, it is vital that we define the factors that influence the interplay between the triad immune system-microbiota-cancer. This knowledge will contribute to improve the therapeutic response to current approaches and will unravel novel targets for immunotherapy.

Gut microbiota in antiviral strategy from bats to humans: a missing link in COVID-19.

Bats are a potential natural reservoir for SARS-CoV-2 virus and other viruses detrimental to humans. Accumulated evidence has shown that, in their adaptation to a flight-based lifestyle, remodeling of the gut microbiota in bats may have contributed to immune tolerance to viruses. This evidence from bats provides profound insights into the potential influence of gut microbiota in COVID-19 disease in humans. Here, we highlight recent advances in our understanding of the mechanisms by which the gut microbiota helps bats tolerate deadly viruses, and summarize the current clinical evidence on the influence of gut microbiota on the susceptibility to SARS-CoV-2 infection and risk of COVID-19 leading to a fatal outcome. In addition, we discuss the implications of gut microbiota-targeted approaches for preventing infection and reducing disease severity in COVID-19 patients.

Evaluation of susceptibility and response in the surface of agents of surface mycoses (Trichophyton mentagrophytes; T. tonsurans) to antifungal drugs of interest in a medical clinic / Avaliação da susceptibilidade e resposta in vitro de agentes de micoses superficiais (Trichophyton mentagrophytes; T. tonsurans) à drogas antifúngicas de interesse em clínica médica

INTRODUCTION: The resistance of fungal species to drugs usually used in clinics is of great interest in the medical field. OBJECTIVE: To evaluate susceptibility and in vitro response of species of Trichophyton spp. to antifungal drugs of interest in clinical medicine. METHODS: 12 samples of clinical isolates from humans were used, nine of T. mentagrophytes and three of T. tonsurans. Susceptibility tests were performed according to the agar diffusion (AD) and broth microdilution (BM) methods. RESULTS: In the AD method, the species T. tonsurans presented a percentage of sensitivity of 33% in relation to amphotericin B and 66% to itraconazole, with 100% resistance to ketoconazole and fluconazole. T. mentagrophytes also showed 100% resistance to ketoconazole in this technique, with 11% sensitivity to ketoconazole, 22% to itraconazole and 22% of samples classified as sensitive dose dependent. In the MC method, the species T. tonsurans presented a sensitivity percentage of 66%, 55% and 33% in relation to ketoconazole, fluconazole and itraconazole, respectively. The T. mentagrophytes species presented sensitivity percentages of 11%, 11%, 33% and 55% for amphotericin B, itraconazole, ketoconazole and fluconazole, respectively. CONCLUSION: There was resistance in vitro of the species of T. mentagrophytes and T. tonsurans against the antifungal fluconazole and relative resistance against ketoconazole in the AD method. In BM, however, important percentages of sensitivity were observed for the two species analyzed in relation to the antifungals fluconazole and ketoconazole when compared to itraconazole and amphotericin B.

INTRODUÇÃO: A resistência de espécies fúngicas às drogas usualmente empregadas no meio clínico é motivo de grande interesse na área médica. OBJETIVO: Avaliar susceptibilidade e resposta in vitro de espécies de Trichophyton spp. a drogas antifúngicas de interesse em clínica médica. MÉTODOS: Foram utilizadas 12 amostras de isolados clínicos de humanos, sendo nove de T. mentagrophytes e três de T. tonsurans. Foram realizados testes de susceptibilidade segundo os métodos de difusão em ágar (DA) e microdiluição em caldo (MC). RESULTADOS: No método de DA, a espécie T. tonsurans apresentou percentual de sensibilidade de 33% em relação à anfotericina B e de 66% ao itraconazol, com 100% de resistência frente ao cetoconazol e ao fluconazol. A espécie T. mentagrophytes também apresentou 100% de resistência frente ao cetoconazol nesta técnica, com 11% de sensibilidade ao cetoconazol, 22% ao itraconazol e 22% das amostras classificadas como sensível dose dependente. No método de MC, a espécie T. tonsurans apresentou percentual de sensibilidade de 66%, 55% e 33% em relação ao cetoconazol, fluconazol e itraconazol, respectivamente. A espécie T. mentagrophytes apresentou percentuais de sensibilidade de 11%, 11%, 33% e 55% para anfotericina B, itraconazol, cetoconazol e fluconazol, respectivamente. CONCLUSÃO: Houve resistência in vitro das espécies do T. mentagrophytes e T. tonsurans frente ao antifúngico fluconazol e resistência relativa frente ao cetoconazol no método de DA. Na MC, no entanto, foram observados importantes percentuais de sensibilidade das duas espécies analisadas frente aos antifúngicos fluconazol e cetoconazol quando comparadas ao itraconazol e à anfotericina B.