Postbióticos: un nuevo miembro en la familia de los bióticos / Postbiotics: A new member in the biotics family

Los postbióticos fueron definidos en 2021 por la Asociación Científica Internacional de Probióticos y Prebióticos (ISAPP) como "una preparación de microorganismos inanimados y/o sus componentes celulares capaces de conferir un efecto benéfico al hospedador". El campo de los postbióticos es un área nueva dentro de la familia de los bióticos; se han desarrollado ya numerosos productos con aplicaciones clínicas, como la estimulación inmunológica, el manejo de diarreas en niños y adultos, el abordaje del intestino irritable, además de tres fórmulas infantiles. En particular, las fórmulas infantiles con postbióticos obtenidos a partir de la fermentación de la leche con Bifidobacterium breve C50 y Streptococcus thermophilus O65, y sus metabolitos, incluido el oligosacárido 3'-GL, han demostrado seguridad y contribución al desarrollo de la microbiota intestinal y el sistema inmune asociado al intestino. Estas modificaciones contribuyen a la prevención y el manejo de los trastornos funcionales digestivos del lactante.

Postbiotics were defined in 2021 by the International Scientific Association for Probiotics and Prebiotics (ISAPP) as a "preparation of inanimate microorganisms and/or their cellular components that confers a health benefit to the host." The field of postbiotics is a new area within the biotics family; numerous products have already been developed for clinical applications, such as immune stimulation, the management of diarrhea in children and adults, the management of irritable bowel syndrome, and 3 infant formulas. In particular, infant formulas with postbiotics obtained from milk fermented with Bifidobacterium breve C50 and Streptococcus thermophilus O65 ­and their metabolites­, including the oligosaccharide 3'-GL, have demonstrated to be safe and to contribute to the development of the gut microbiota and the gutassociated immune system. These modifications help to prevent and manage functional gastrointestinal disorders in infants.

Diagnóstico de tuberculosis en pediatría / Diagnosis of tuberculosis in pediatrics

La tuberculosis sigue siendo una epidemia mundial y en Chile no ha mostrado una tendencia descendente en los últimos años, con un aumento en los casos infantiles. En los niños, el diagnóstico es un reto debido a la baja carga bacilar y las características de las lesiones, que suelen ser cerradas. Métodos tradicionales como los cultivos, considerados anteriormente como el gold standard, con frecuencia arrojan resultados negativos. Sin embargo, los avances en pruebas moleculares han permitido un progreso significativo en la confirmación bacteriológica. Otras herramientas diagnósticas, como la prueba de tuberculina (PPD) y los ensayos de liberación de interferón gamma (IGRAs), tienen sensibilidades y especificidades variables, siendo útiles como pruebas complementarias. Las imágenes juegan un papel clave en la evaluación diagnóstica de tuberculosis pulmonar y extrapulmonar en pacientes pediátricos. Esta revisión aborda la epidemiología y el proceso diagnóstico de la tuberculosis infantil.

Tuberculosis remains a global epidemic, and in Chile, it has not shown a downward trend in recent years, with an increase in pediatric cases. Diagnosing tuberculosis in children presents challenges due to the low bacillary load and the closed nature of the lesions. Traditional methods like cultures, once considered the gold standard, often yield negative results. However, advances in molecular testing have significantly improved bacteriological confirmation. Other diagnostic tools, such as the tuberculin skin test (PPD) and interferon-gamma release assays (IGRAs), offer variable sensitivities and specificities and are useful as complementary tests. Imaging plays a critical role in the diagnostic evaluation of pulmonary and extrapulmonary tuberculosis in pediatric patients. This review addresses the epidemiology and diagnostic process of pediatric tuberculosis.

An outbreak of severe or lethal infections by a multidrug-resistant Acinetobacter baumannii ST126 strain carrying a plasmid with blaNDM-1 and blaOXA-58 carbapenemases.

Acinetobacter baumannii poses a significant health threat because of its frequent implications in hospital outbreaks and multidrug resistance (MDR). Here, we studied four A. baumannii isolates recovered during a hospital outbreak of severe or fatal cases to elucidate their diversity and factors contributing to their increased virulence and antibiotic resistance. The isolates were identified using MALDI-ToF and characterized using comparative genomics, PCR, and antimicrobial susceptibility tests. They were classified as ST126 and exhibited fewer than five chromosomal single-nucleotide variants and the same extrachromosomal content, indicating that they are a single strain (A. baumannii AB01). A. baumannii AB01 showed an MDR phenotype that could be linked to the carriage of parC and gyrA mutations, efflux transporters, aminoglycoside resistance genes, a class C beta-lactamase, and three carbapenemases, some of which are encoded on a 72 kb plasmid. ST126 is infrequent and has not been reported in Latin America, and our genomic data indicate a plausible origin for A. baumannii AB01 within the Pan Pacific region.

Neisseria gonorrhoeae ST-1901 in Rio de Janeiro from 2006 to 2022: Phylogeny and antimicrobial resistance evolution of a well-succeeded pathogen.

Neisseria gonorrhoeae is a global threat to public health due to the accumulation of antimicrobial resistance mechanisms. ST-1901 is an internationally important sequence type (ST) because of its high incidence and the usual occurrence of chromosomally determined resistance. In this study, we describe the evolution of the ST-1901 and its single locus variants in Rio de Janeiro from 2006 to 2022. We analyzed 82 N. gonorrhoeae isolates according to antimicrobial susceptibility profile, resistance mechanisms, molecular typing, and phylogenetics. Six different single locus variants were detected. Phylogenetic analysis identified five clades, which share similar characteristics. Resistance rates for penicillin and tetracycline decreased due to the lower occurrence of resistance plasmids, but intermediary resistance to penicillin rose. Resistance to ciprofloxacin remained high throughout all clades and the years of the study. Regarding resistance to azithromycin, alterations in mtrR promoter and gene, and 23S rRNA encoding gene rrl were detected, with a notable rise in the incidence of C2611T mutations in more recent years occurring in four of five clades. In contrast, ß-lactam resistance associated penA 34 mosaic was found only in one persisting clade (Clade D), and unique G45D and A39T mutations in mtrR gene and its promoter (Nm-Like) were found only in Clade B. Taken together, these data suggest that ST-1901, a persistently circulating lineage of N. gonorrhoeae in Rio de Janeiro, has undergone changes over the years and may evolve to develop resistance to the current recommended dual therapy adopted in Brazil, namely, ceftriaxone and azithromycin.

Duddingtonia flagrans and its crude proteolytic extract: concomitant action in sheep coprocultures.

The presence of infective larvae (L3) of gastrointestinal nematode (GIN) parasites in pastures directly contributes to the constant recurrence of infections in ruminant herds. This study aimed to evaluate the nematophagous fungus Duddingtonia flagrans (AC001) (proteolytic crude extract and/or conidia) in the in vitro control of GIN L3 in coprocultures. To produce the proteolytic crude extract, a suspension (107 conidia/mL) of D. flagrans was inoculated into a liquid medium. After 6 days, the medium was filtered, centrifuged, and its proteolytic activity was measured. For the experimental assay, fecal samples were collected directly from the rectal ampulla of naturally infected sheep, and egg counts per gram of feces (EPG) were performed. Coprocultures were prepared using 10 g of fecal material with the groups defined as follows: control group G1 (1.0 mL of denatured proteolytic crude extract); treated group G2 (1.0 mL of active proteolytic crude extract); treated group G3 (1.0 mL of active proteolytic crude extract + 1.0 mL of AC001 conidia). The coprocultures were maintained at room temperature (25ºC), for 7 days, and then the L3 larvae were recovered. The results demonstrated that AC001 successfully produced protease (56.34 U/mL). The treatments with active proteolytic crude extract (G2) and active proteolytic crude extract + AC001 conidia (G3) were significantly different (p < 0.01) from the control group with denatured proteolytic crude extract (G1). AC001 and its proteolytic crude extract acted concomitantly on helminths directly in the fecal environment, suggesting potential future applications in the field.

Assessing refrigerated preservation performance using Listeria predictive microbiology models and temperature data: Refrigerator performance indicator and time-temperature equivalent.

Time-temperature data for queso fresco (QF) cheese varieties stored in a residential refrigerator operating at 5°C and a predictive microbiology secondary model for Listeria monocytogenes in QF were used to estimate a refrigerator performance indicator (RPI) of microbial preservation. RPI values were used to assess how compressor technology (single [SS] and variable speed [VS]), ambient temperature (21.1°C [LT] and 32.2°C [HT]), and refrigerator load (22.5 kg regular load and 39 kg higher load) affected preservation performance. All deterministic and probabilistic RPI estimations slightly exceeded the desirable 1.0 value, i.e., the variable temperatures for the QF kept in the refrigerator were worse than keeping it constantly at the temperature recommended by food safety agencies for QF. Furthermore, the mean comparison of estimates of the time-temperature equivalent indicator previously developed by French researchers showed similar behavior to those observed for RPI. Finally, statistical analysis showed that Tambient was the factor with the highest impact on refrigerator performance because of its impact on the sample temperature increase during door openings and when exposed to ambient temperature during product use. This highlights the need to reduce the time for product temperature recovery by improving the compressor operation logic. Also important are consumer behavior changes such as a reduction in product exposure to ambient temperature and in the door opening duration and frequency. PRACTICAL APPLICATION: This study demonstrated how a quantitative tool (RPI) can assess refrigerator preservation performance. Although the findings presented can be applied to any cold chain segment, the data used was collected for its weakest link, the domestic refrigerator. Surveys show that 77% of them operate above the recommended 4°C. The RPI methodology is ready for use by refrigerator designers to assess performance improvements possible by modifications of the compressor operation logic. Moreover, it can be integrated into smart-hubs monitoring the frequency and duration of refrigerator door openings to inform consumers when their habits are compromising the preservation performance of the refrigerator.

Evaluating quasi-experimental approaches for estimating epidemiological efficacy of non-randomised field trials: applications in Wolbachia interventions for dengue.

BACKGROUND: Wolbachia symbiosis in Aedes aegypti is an emerging biocontrol measure against dengue. However, assessing its real-world efficacy is challenging due to the non-randomised, field-based nature of most intervention studies. This research re-evaluates the spatial-temporal impact of Wolbachia interventions on dengue incidence using a large battery of quasi-experimental methods and assesses each method's validity. METHODS: A systematic search for Wolbachia intervention data was conducted via PUBMED. Efficacy was reassessed using commonly-used quasi-experimental approaches with extensive robustness checks, including geospatial placebo tests and a simulation study. Intervention efficacies across multiple study sites were computed using high-resolution aggregations to examine heterogeneities across sites and study periods. We further designed a stochastic simulation framework to assess the methods' ability to estimate intervention efficacies (IE). RESULTS: Wolbachia interventions in Singapore, Malaysia, and Brazil significantly decreased dengue incidence, with reductions ranging from 48.17% to 69.19%. IEs varied with location and duration. Malaysia showed increasing efficacy over time, while Brazil exhibited initial success with subsequent decline, hinting at operational challenges. Singapore's strategy was highly effective despite partial saturation. Simulations identified Synthetic Control Methods (SCM) and its variant, count Synthetic Control Method (cSCM), as superior in precision, with the smallest percentage errors in efficacy estimation. These methods also demonstrated robustness in placebo tests. CONCLUSIONS: Wolbachia interventions exhibit consistent protective effects against dengue. SCM and cSCM provided the most precise and robust estimates of IEs, validated across simulated and real-world settings.

Bacillus altitudinis 1.4 genome analysis-functional annotation of probiotic properties and immunomodulatory activity.

Probiotics are live microorganisms that, when administered in adequate quantities, provide health benefits to the host. In this study, phenotypic and genotypic methods were used to evaluate the probiotic properties of Bacillus altitudinis 1.4. The isolate was sensitive to all antimicrobials tested and presented a positive result in the hemolysis test. B. altitudinis 1.4 spores were more resistant than vegetative cells, when evaluated in simulation of cell viability in the gastrointestinal tract, as well as adhesion to the intestinal mucosa. The isolate was capable of self-aggregation and coaggregation with pathogens such as Escherichia coli ATCC 25922 and Salmonella Enteritidis ATCC 13076. Genomic analysis revealed the presence of genes with probiotic characteristics. From this study it was possible to evaluate the gene expression of pro-inflammatory and anti-inflammatory cytokines for different treatments. Viable vegetative cells of B. altitudinis 1.4 increased the transcription of pro-inflammatory factors, in addition to also increasing the transcription of IL-10, indicating a tendency to stimulate a pro-inflammatory profile. Given the results presented, B. altitudinis 1.4 showed potential to be applied in the incorporation of this microorganism into animal feed, since the spores could tolerate the feed handling and pelletization processes.

Sequencing, assembly, and genomic annotation of Leucoagaricus gongylophorus LEU18496, a dikarya mutualistic species.

The basidiomycete fungus Leucoagaricus gongylophorus is able to grow in the fungus garden of leaf-cutter ants. This mutualistic interaction has driven the evolutionary adaptation of L. gongylophorus, shaping its metabolism to produce enzymes adept at lignocellulosic biomass degradation. In this study, we undertook the comprehensive sequencing, assembly, and functional annotation of the genome of L. gongylophorus strain LEU18496, mutualistic fungus of the Atta mexicana. Our genomic analyses revealed a distinctive bimodal nature to the genome: a predominant region characterized by AT enrichment and low genetic density, alongside a smaller region exhibiting higher GC content and higher genetic density. The presence of transposable elements (TEs) within the AT-enriched region suggests genomic compartmentalization, facilitating differential evolutionary rates. With a gene count of 6748, the assembled genome of L. gongylophorus LEU18496 surpasses previous reports for this fungal species. Inspection of genes associated with central metabolism unveiled a remarkable abundance of carbohydrate-active enzymes (CAZymes) and fungal oxidative lignin enzymes (FOLymes), underscoring their pivotal roles in the life cycle of this fungus.

Optimizing ozone treatment for pathogen removal and disinfection by-product control for potable reuse at pilot-scale.

Reclaimed water poses environmental and human health risks due to residual organic micropollutants and pathogens. Ozonation of reclaimed water to control pathogens and trace organics is an important step in advanced water treatment systems for potable reuse of reclaimed water. Ensuring efficient pathogen reduction while controlling disinfection byproducts remains a significant challenge to implementing ozonation in reclaimed water reuse applications. This study aimed to investigate ozonation conditions using a plug flow reactor (PFR) to achieve effective pathogen removal/inactivation while minimizing bromate and N-Nitrosodimethylamine (NDMA) formation. The pilot scale study was conducted using three doses of ozone (0.7, 1.0 and 1.4 ozone/total organic carbon (O3/TOC) ratio) to determine the disinfection performance using actual reclaimed water. The disinfection efficiency was assessed by measuring total coliforms, Escherichia coli (E. coli), Pepper Mild Mottle Virus (PMMoV), Tomato Brown Rugose Fruit Virus (ToBRFV) and Norovirus (HNoV). The ozone CT values ranged from 1.60 to 13.62 mg min L-1, resulting in significant reductions in pathogens and indicators. Specifically, ozone treatment led to concentration reductions of 2.46-2.89, 2.03-2.18, 0.46-1.63, 2.23-2.64 and > 4 log for total coliforms, E. coli, PMMoV, ToBRFV, and HNoV, respectively. After ozonation, concentrations of bromate and NDMA increased, reaching levels between 2.8 and 12.0 µg L-1, and 28-40.0 ng L-1, respectively, for average feed water bromide levels of 86.7 ± 1.8 µg L-1 and TOC levels of 7.2 ± 0.1 mg L-1. The increases in DBP formation were pronounced with higher ozone dosages, possibly requiring removal/control in subsequent treatment steps in some potable reuse applications.

Estimating taxonomic and functional structure along a tropical estuary: linking metabolic traits and aspects of ecosystem functioning.

Microbial life forms are among the most ubiquitous on Earth, yet many remain understudied in Caribbean estuaries. We report on the prokaryote community composition of the Urabá Estuary in the Colombian Caribbean using 16S rRNA gene-transcript sequencing. We also assessed potential functional diversity through 38 metabolic traits inferred from 16S rRNA gene data. Water samples were collected from six sampling stations at two depths with contrasting light-penetration conditions along an approximately 100 km transect in the Gulf of Urabá in December 2019. Non-metric multidimensional scaling analysis grouped the samples into two distinct clusters along the transect and between depths. The primary variables influencing the prokaryote community composition were the sampling station, depth, salinity, and dissolved oxygen levels. Twenty percent of genera (i.e., 58 out 285) account for 95% of the differences between groups along the transect and among depths. All of the 38 metabolic traits studied showed some significant relationship with the tested environmental variables, especially salinity and except with temperature. Another non-metric multidimensional scaling analysis, based on community-weighted mean of traits, also grouped the samples in two clusters along the transect and over depth. Biodiversity facets, such as richness, evenness, and redundancy, indicated that environmental variations-stemming from river discharges-introduce an imbalance in functional diversity between surface prokaryote communities closer to the estuary's head and bottom communities closer to the ocean. Our research broadens the use of 16S rRNA gene transcripts beyond mere taxonomic assignments, furthering the field of trait-based prokaryote community ecology in transitional aquatic ecosystems.IMPORTANCEThe resilience of a dynamic ecosystem is directly tied to the ability of its microbes to navigate environmental gradients. This study delves into the changes in prokaryote community composition and functional diversity within the Urabá Estuary (Colombian Caribbean) for the first time. We integrate data from 16S rRNA gene transcripts (taxonomic and functional) with environmental variability to gain an understanding of this under-researched ecosystem using a multi-faceted macroecological framework. We found that significant shifts in prokaryote composition and in primary changes in functional diversity were influenced by physical-chemical fluctuations across the estuary's environmental gradient. Furthermore, we identified a potential disparity in functional diversity. Near-surface communities closer to the estuary's head exhibited differences compared to deeper communities situated farther away. Our research serves as a roadmap for posing new inquiries about the potential functional diversity of prokaryote communities in highly dynamic ecosystems, pushing forward the domain of multi-trait-based prokaryote community ecology.

Diversity of endophytic bacteria with antimicrobial potential isolated from marine macroalgae from Yacila and Cangrejos beaches, Piura-Peru.

Endophytic bacteria found in marine macroalgae have been studied for their potential antimicrobial activity, consequently, they could serve as a valuable source of bioactive compounds to control pathogenic bacteria, yeasts, and fungi. Algae endophytic bacteria were isolated from Caulerpa sp., Ulva sp., Ahnfeltiopsis sp., and Chondracantus chamissoi from Yacila and Cangrejo Beaches (Piura, Peru). Antimicrobial assays against pathogenic bacteria were evaluated using cross-culture, over-plate, and volatile organic compound tests. Afterward, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of selected crude extracts were determined, also ITS molecular analysis, antifungal activity, and PCR of iturin, fengycin, and surfactin genes were performed for bacteria strains exhibiting better activity. Forty-six algae endophytic bacteria were isolated from algae. Ten strains inhibited gram-positive pathogenic bacteria (Enterococcus faecalis, Staphylococcus epidermidis, S. aureus, and Listeria monocytogenes), and 12 inhibited gram-negative bacteria (Escherichia coli and Salmonella enteric sv typhimurium). Bacteria with better activity belong to Bacillus sp., Kluyvera ascorbata, Pantoea agglomerans, Leclercia adecarboxylata, and Enterobacter sp., which only four showed antifungal activities against Candida albicans, C. tropicalis, Colletotrichium sp., Fusarium sp., Fusarium oxysporum, and Alternaria sp. Furthermore, K. ascorbata YAFE21 and Bacillus sp. YCFE4 exhibited iturin and fengycin genes. The results indicate that the algae endophytic bacteria found in this study, particularly K. ascorbata YAFE21, Bacillus sp. YCFR6, L. adecarboxylata CUFE2, Bacillus sp. YUFE8, Enterobacter sp. YAFL1, and P. agglomerans YAFL6, could be investigated as potential producers of antimicrobial compounds due to their broad activity against various microorganisms.

Treatment of multidrug-resistant Gram-negative bloodstream infections in critically ill patients: an update.

PURPOSE OF REVIEW: This review describes the latest information in the management of bloodstream infections caused by multidrug-resistant Gram-negative bacilli (MDRGNB) in critically ill patients. RECENT FINDINGS: The prevalence of bloodstream infections due to MDRGNB is high, and they pose a significant risk in critically ill patients. Recently, novel antimicrobial agents, including new ß-lactam/ß-lactamase inhibitor combinations and cefiderocol, have been introduced for treating these infections. Concurrently, updated guidelines have been issued to aid in treatment decisions. Prompt diagnosis and identification of resistance patterns are crucial for initiating effective antibiotic therapy. Current studies, especially with observational design, and with limited sample sizes and patients with bacteremia, suggest that the use of these new antibiotics is associated with improved outcomes in critically ill patients with MDRGNB bloodstream infections. SUMMARY: For critically ill patients with bloodstream infections caused by MDRGNB, the use of newly developed antibiotics is recommended based on limited observational evidence. Further randomized clinical trials are necessary to determine the most effective antimicrobial therapies among the available options.

In vitro assessment of NaF/Chit supramolecular complex: Colloidal stability, antibacterial activity and enamel protection against S. mutans biofilm.

OBJECTIVES: This study assessed the effect of NaF/Chit suspensions on enamel and on S. mutans biofilm, simulating application of a mouthrinse. METHODS: The NaF/Chit particle suspensions were prepared at molar ratio [NaF]/Chitmon]≈0.68 at nominal concentrations of 0.2 % and 0.05 % NaF and characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering and zeta potential. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured. The S. mutans biofilm was formed for 7 days on eighty human enamel blocks that were divided into eight groups (n = 10/group): i) 0.05 % NaF solution; ii) 0.31 % Chit solution; iii) NaF/Chit(R=0.68) suspension at 0.05 % NaF; iv) 1.0 % HAc solution (Control); v) 0.2 % NaF solution; vi) 1.25 % Chit solution; vii) NaF/Chit(R=0.68) suspension at 0.2 % NaF; viii) 0.12 % chlorhexidine digluconate. The substances were applied daily for 90 s. S. mutans cell counts (CFU/mL) were performed, and the Knoop microhardness (KHN) of enamel samples were measured before and after biofilm formation. The KHN and CFU/mL data were analyzed by repeated measure ANOVA and Tukey's test (α = 0.05). RESULTS: Interactions between NaF and Chit were evidenced in solid state by FTIR spectra. The NaF/Chit complexes showed spontaneous microparticle formation and colloidal stability. The MIC and MBC ranged from 0.65 to 1.31 mg/mL. The NaF/Chit(R=0.68) suspension at 0.2 %NaF Group showed lower CFU/mL values than other groups. The NaF/Chit(R=0.68) suspensions Groups had the highest KHN values after biofilm formation. CONCLUSIONS: The NaF/Chit(R=0.68) complexes exhibited an antibacterial effect against S. mutans biofilm and reduced the enamel hardness loss. CLINICAL SIGNIFICANCE: The NaF/Chit(R=0.68) suspensions showed potential to be used as a mouthrinse for caries prevention.

Detection of Mycobacterium tuberculosis transrenal DNA in urine samples among adults in Peru.

Diagnosis of pulmonary tuberculosis (TB) relies on a sputum sample, which cannot be obtained from all symptomatic individuals. Mycobacterium tuberculosis (Mtb) transrenal DNA (trDNA) has been detected in urine, an easily obtainable, noninvasive, alternative sample type. However, reported sensitivities have been variable and likely depend on collection and assay procedures and aspects of trDNA biology. We analyzed three serial urine samples from each of 75 adults with culture-confirmed pulmonary TB disease in Lima, Peru for detection of trDNA using short-fragment real-time PCR. Additionally, we examined host, urine, and sampling factors associated with detection. Overall per-sample sensitivity was 38 % (95 % Confidence Interval [CI] 30-45 %). On an individual level (i.e., any of the three samples positive), sensitivity was 73 % (95 % CI: 62-83 %). Sensitivity was highest among samples from patients with smear-positive TB, 92 % (95 % CI: 62-100 %). Specificity from a single sample from each of 10 healthy controls was 100 % (95 % CI: 69-100 %). Adjusting our assay positivity threshold increased individual-level sensitivity to 88 % (95 % CI: 78-94 %) overall without affecting the specificity. We did not find associations between Mtb trDNA detection and individual characteristics or urine sample characteristics. Overall, our results support the potential of trDNA detection for TB diagnosis.

Factors influencing fumonisin B1 contamination in maize: insights from two production regions in Costa Rica.

Maize (Zea mays L.) is an important cereal crop worldwide. Contaminated maize kernels pose a significant mycotoxin exposure risk for humans in Latin America. Fumonisins, the most prevalent mycotoxin in maize, typically occur during pre-harvest conditions leading to significant economic losses. Various factors, including weather conditions, may influence this contamination. This study aimed to determine the association between fumonisin B1 (FB1) contamination, prevalence of Fusarium verticillioides, weather conditions and kernel quality in the two primary maize production areas in Costa Rica (Brunca and Chorotega). All maize samples (100%) showed FB1 contamination, with higher concentrations in samples from Brunca region, consistent with the presence of F. verticilliodes. Weather conditions appeared to play an important role in this contamination, since Brunca region had the highest mean temperature and relative humidity after maize silking (R1) and the total monthly rainfall in this region was significantly higher during the last two months of maize cultivation (grain-filling and physiological maturity stages R3 to R6). Interestingly, this study found a negative correlation between grain damage and kernel contamination with FB1 and F. verticillioides. The concentration of mineral nutrients in kernels from both regions was largely similar. Most nutrients in kernels exhibited a negative correlation with FB1, particularly nitrogen. Zinc and phosphorus were the only nutrients in kernels showing a positive correlation with FB1 in samples from the Brunca region. The results highlight elevated levels of FB1 contamination in maize and contribute to a better understanding of pre-harvest factors influencing FB1 contamination in tropical conditions.

Loop-Mediated Isothermal Amplification for the Diagnosis of Sporotrichosis by Sporothrix brasiliensis.

We aimed to develop and validate a Loop-mediated Isothermal Amplification (LAMP) assay to Sporothrix brasiliensis. LAMP reaction was developed using six primers designed based on calmodulin gene. In the LAMP reaction, we tested twenty isolates of S. brasiliensis from animals and humans, along with ten tissue samples extracted from the left footpad of mice that had been experimentally infected with S. brasiliensis. In addition, it included DNA samples from various other fungal species for specificity evaluation. All S. brasiliensis isolates yielded positive results in the LAMP, and the limit of DNA detection was 1 ng/µL. All murine samples were positive in the test while DNA from other fungal species were all negative, resulting in 100% of sensitivity and specificity of primers. LAMP diagnosis technique is a promising alternative to sporotrichosis diagnosis, in a simple and cost-effective way. Further studies are warranted to validate this technique using animal model samples obtained from both humans and animals.

Fusarium Keratitis: A Systematic Review (1969 to 2023).

BACKGROUND: Mycotic keratitis (MK) represents a corneal infection, with Fusarium species identified as the leading cause. Fusarium is a genus of filamentous fungi commonly found in soil and plants. While many Fusarium species are harmless, some can cause serious infections in humans and animals, particularly Fusarium keratitis, that can lead to severe ocular infections, prevalent cause of monocular blindness in tropical and subtropical regions of the world. Due to its incidence and importance in ophthalmology, we conducted a systematic analysis of clinical cases to increase our understanding of Fusarium keratitis by gathering clinical and demographic data. METHODS: To conduct an analysis of Fusarium keratitis, we looked through the literature from the databases PubMed, Embase, Lilacs, and Google Scholar and found 99 papers that, between March 1969 and September 2023, corresponded to 163 cases of Fusarium keratitis. RESULTS: Our analysis revealed the Fusarium solani species complex as the predominant isolate, with females disproportionately affected by Fusarium keratitis. Notably, contact lens usage emerged as a significant risk factor, implicated in nearly half of cases. Diagnosis primarily relied on culture, while treatment predominantly involved topical natamycin, amphotericin B, and/or voriconazole. Surprisingly, our findings demonstrated a prevalence of cases originating from the United States, suggesting potential underreporting and underestimation of this mycosis in tropical regions. This shows the imperative for heightened vigilance, particularly in underdeveloped regions with substantial agricultural activity, where Fusarium infections may be more prevalent than currently reported. CONCLUSION: Our study sheds light on the clinical complexities of Fusarium keratitis and emphasizes the need for further research and surveillance to effectively tackle this vision-threatening condition. Furthermore, a timely identification and early initiation of antifungal treatment appear to be as important as the choice of initial treatment itself.

Development and evaluation of a colorimetric LAMP based-assay targeting the Bacteroides HF183 marker for tracking sewage pollution in environmental waters.

Surface waters are vulnerable to contamination by human and animal feces, posing risks to human health due to potential exposure to enteric pathogens. This research developed a colorimetric loop-mediated isothermal amplification (cLAMP) assay to detect sewage associated Bacteroides dorei HF183/BacR287 (HF183) marker in wastewater and environmental water samples. The host sensitivity and host specificity of the assay were evaluated, and their performance was compared to the Bacteroides HF183 qPCR assay using control materials (gBlocks), environmental water samples seeded with untreated sewage, and ambient environmental water samples. In serial dilutions of control materials, qPCR produced quantifiable data across all dilutions, while cLAMP detected the marker down to 0.001 pg/µL of control materials, which was two orders of magnitude less sensitive than qPCR. All untreated sewage samples (n = 12) tested positive for HF183 by both the qPCR and cLAMP assays, demonstrating a host sensitivity value of 1.00 (maximum value of 1.00). The host specificity by analysing 70 non-human fecal nucleic acid samples revealed cLAMP's specificity value of 0.81 compared to qPCR's 0.64. When testing sewage-seeded environmental water samples, both methods detected HF183 for the lowest amount of sewage, indicating similar detection sensitivity. The application of cLAMP for tracking sewage pollution in environmental waters showed promising results, with moderate agreement between cLAMP and qPCR (κ = 0.510). However, cLAMP occasionally missed detections compared to qPCR, particularly in low-concentration samples. Overall, the cLAMP HF183 assay demonstrated promising potential as a rapid and sensitive method for detecting sewage pollution, offering a viable alternative to qPCR in certain environmental monitoring scenarios.