Brazilian Journal of Microbiology最新文献

Due to the limitations in antiviral treatments for viral infections, the search for natural compounds with biocompatible and antiviral activities has gained importance. In this study, we investigated the antiviral efficacy of a unique formulation (DEO/TA-mix, Uluvir^®) at the stages of viral replication, adsorption, penetration, repeated doses, and direct inactivation of the selected model virus, Bovine coronavirus (BCoV). In the presence of DEO (from Anethum graveolens L.)/ TA (Quercus infectoria extract) mix, 99.94% inhibition was observed in the mean viral titer values of BCoV at the 48th h of replication, while the inhibition activity stopped at the 96th h. With the addition of DEO/TA-mix every 48 h after virus inoculation, viral replication was inhibited by 98.79% at the 120th h. Treatment of BCoV with DEO/TA-mix showed 99.58% inhibition at the adsorption stage and 43.77% inhibition at the penetration stage in the viral titer. In the direct inactivation efficacy of DEO/TA-mix on BCoV, the mean viral titers decreased by 0.5 to 3.0 log in a time-dependent manner. The antiviral activity of DEO/TA-mix is predicted to be more effective in the early stages of BCoV replication. In addition, an additional dose of DEO/TA-mix every 48 h during the viral replication phase increases and prolongs the inhibition rates on viral titers. This study has demonstrated that DEO/TA-mix shares high antiviral activity and may be evaluated as a potential drug for virus infections.

Bovine tuberculosis is a disease of importance for animal and public health, as it causes chronic infection in both animals and humans, leads to reduced milk and meat productivity, and may generate embargoes on the trade of products from affected herds. The Brazilian National Program for the Control and Eradication of Brucellosis and Tuberculosis (in Portuguese, PNCEBT) classifies the Brazilian states according to the level of risk for bovine brucellosis and tuberculosis determined by the prevalence of outbreaks of these diseases. The present study aimed to: determine the prevalence of outbreaks and cattle with tuberculosis in the State of São Paulo; locate the origin of animals microbiologically and molecularly positive for Mycobacterium bovis; establish microbiological differential diagnoses of inflammatory lesions found in slaughtered animals; and map areas of attention for the occurrence of M. bovis. The territory analyzed was divided into 15 administrative regions, and samples of tissues and organs were collected from 301 bovines from slaughterhouses registered at the São Paulo State Inspection Service (in Portuguese, SISP). Samples were subjected to microbiological culture in selective Stonebrink-Leslie medium, and conventional blood agar and MacConkey media. Colonies isolated in conventional media were analyzed by Matrix Assisted Laser Desorption Ionization (MALDI-TOF), and colonies isolated in Stonebrink-Leslie were subjected to Polymerase Chain Reaction (PCR) with primers from region of difference 4 (RD4) for confirmation of M. bovis. Data on cattle movement into and out of tuberculosis foci were geoprocessed in the QGIS software, version 3.28.1, to map the cities that could be involved. Samples from eight bovines (2.65%; CI 95% = 1,15% - 5,17%) showed mycobacteria in Stonebrink-Leslie medium and were confirmed as M. bovis. The prevalence rates of tuberculosis in cattle and in foci in rural properties were 2.65% and 5.94%, respectively. Mass spectrometry identified the most frequent bacteria in the samples analyzed: Trueperella pyogenes (10/301 = 3.32%), Macrococcus caseolyticus (9/301 = 2.99%), Escherichia coli (8/301 = 2.65%), Macrococcus canis (5/301 = 1.66%), Moraxella osloensis (4/301 = 1.32%), Lactococcus garvieae (3/301 = 0.99%), and Proteus hauseri (3/301 = 0.99%). The animal transportation forms (in Portuguese, GTAs) of animals positive for M. bovis indicated six rural properties with outbreaks. Geoprocessing showed 28 municipalities considered attention zones. The identification of M. bovis and other microorganisms in cattle reinforces the importance of slaughterhouses as sites for surveillance and traceability of infectious diseases, and emphasizes their role in ensuring the safety of animal products intended for human consumption.

Controlling aflatoxin M₁ (AFM₁) in milk and dairy products is of critical importance due to its persistent global threat to public health and significant economic impact on the dairy industry. This study aimed to evaluate the effect of nano-chitosan and clay bentonite on AFM₁ in spiked UHT cow's milk and their impact on its sensory attributes and composition. The AFM₁ concentration was reduced by 64.5%, 76.3%, and 80.2% at 0.25%, 0.5%, and 1.0% concentrations of nano-chitosan, respectively. Regarding bentonite, the AFM₁ concentration was reduced by 21.7%, 34.2%, and 38.6% at 0.25%, 0.5%, and 1.0% concentrations, respectively. Results indicated significant differences (p < 0.05) in AFM₁ reduction among different concentrations of nano-chitosan and bentonite. This study provides the first reported data on the sensory profile of milk (flavor, color, and appearance) following detoxification with nano-chitosan and bentonite. No significant difference (p > 0.05) was detected in the sensory parameters of the milk samples treated with either nano-chitosan or bentonite. Milk protein (3.8%), fat (3.1%), lactose (4.3%), solids not-fat (8.2%), ash (0.6%), titratable acidity percentage (0.15%), and pH (6.6%) were significantly unaffected. This in vitro study demonstrates the significant efficacy of nano-chitosan, and to a lesser degree bentonite, for adsorbing AFM₁ from UHT milk without altering its sensory properties. Efficacy in spiked milk warrants validation in naturally contaminated samples to confirm practical applicability.

The genus Corynebacterium comprises several valid species, yet most studies focus on Corynebacterium diphtheriae. Infections by non-diphtherial species are increasingly reported, despite limited genomic and pathogenicity data. Corynebacterium hesseae was recently described and isolated from clinical samples, warranting further investigation into its phenotypic characteristics and potential clinical significance. In the context, this study aimed to investigate the first reported case of systemic infection caused by C. hesseae in an elderly patient from south-central Brazil. The study focused on identifying the isolate using genomic tools, characterizing its antimicrobial resistance (AMR) profile, and assessing its virulence through phenotypic and genomic analyses. The isolate, misidentified as Corynebacterium aurimucosum by MALDI-TOF MS, was confirmed as C. hesseae through genomic analyses (ANI: 96.36%, dDDH: 84.9%). The genome (2.8 Mb, 60.84% G + C content) revealed virulence genes (sapD, srtB, fagBCD) and AMR genes (ermX, tetA, tetW, aph(3')-Ia, aph(6)-Id, and cmx). The strain exhibited multidrug resistance (MDR) to penicillin, clindamycin, ciprofloxacin, and tetracycline, with resistance linked to AMR genes and gyrA mutations. Biofilm assays showed strong adhesion, and Galleria mellonella testing demonstrated 70% mortality, confirming pathogenicity. Further studies are needed to elucidate penicillin resistance mechanisms. This study confirms C. hesseae as an emerging pathogen with MDR and significant virulence potential. The misidentification by MALDI-TOF MS emphasizes the importance of genomic tools for accurate pathogen identification and characterization. The findings underscore the critical need for enhanced genomic monitoring, updated microbial identification databases, and continued surveillance of MDR pathogens. These efforts are essential to mitigate the rising threat of AMR and improve infection control strategies, particularly in healthcare settings managing emerging pathogens like C. hesseae.

The study investigates the efficacy of nanoencapsulated antifungal formulation (Ne-CIM) against the growth and zearalenone toxin production by Fusarium graminearum with a detailed mechanism of action. Antifungal and zearalenone toxin inhibitory effects of individual essential oils (EOs) (Carum carvi, and Illicium verum), methyl anthranilate, and their combination (CIM; 1:1:0.5) were recorded in terms of minimum inhibitory concentration (MIC) at (0.80, 0.50, 0.70 and 0.50 µl/ml) and (0.60, 0.40, 0.60 and 0.40 µl/ml) respectively. The antifungal formulation CIM was nanoencapsulated inside the chitosan nanogel and characterized using FTIR, DLS, and XRD. The result revealed that Ne-CIM exhibited elevated antifungal and zearalenone toxin inhibition at 0.40 and 0.30 µl/ml respectively which was found to be superior over the individual EOs and mixture formulation. Further, the mechanism of action of Ne-CIM was also explored by targeting the membrane ergosterol, ion leakage, 260/280 absorbing material, antioxidant enzymes, and carbon source utilization level. The result reveals the remarkable impairment in test biochemical parameters over to control. In addition, the practical applicability of Ne-CIM was investigated using in-situ experiments with inoculated toxigenic F. graminearum in raw material from Withania somnifera. The result revealed that at MIC value Ne-CIM protects 70% of fungal growth and 100% of zearalenone toxin, with remarkable protection from lipid peroxidation. The study recommends the Ne-CIM as a novel green antifungal agent for sustainable management of toxigenic F. graminearum.

Mycobacterium tuberculosis (Mtb) is the pathogen that causes tuberculosis (TB). This disease affects one-third of the world's population, mainly in its latent form. The use of reverse vaccinology and immunoinformatics stands out for the production of vaccines based on peptides or proteins, since they are more specific, safe, effective and economical. The present study evaluated the immunological potential of the proteins MPT83 and MPT51 for vaccine production, comparing them with MPT64. To do this, the sequences of these proteins from MTB H37Rv were downloaded and analyzed. The prediction of T and B cell epitopes was performed, and the adjuvant (50 S L7/L12) was included in the fusion of MPT83 and MPT51 to enhance the immune response. The allergenicity, antigenicity, solubility and physicochemical properties of the fused protein fragments were evaluated. Through different programs, a variety of bioinformatics tools were used to predict, analyze and validate the tertiary structure. The results of the in silico immunological simulation of the chimeric protein demonstrated that the best region for use as an epitope is the initial part of MPT83, consisting of 100 amino acid residues, and the final portion of MPT51, consisting of 99 amino acid residues, with a significant immunological response, excellent antigenicity (1.02) and no allergenicity. The secondary structure revealed that the majority of alpha-helices are in the initial part of the proteins, and the chimeric vaccine has 3 beta strands along its length. Finally, the chimeric vaccine candidate and MPT64 were efficiently cloned into the bacterial vector and successfully expressed in Escherichia coli thereby facilitating future in vivo studies with potentially promising results.

Salmonellosis linked to fish consumption is a significant public health concern. Salmonella often contaminates fish through polluted water or improper handling, with increasing antibiotic-resistant strains in aquaculture. This study evaluated the antimicrobial, antioxidant, and anti-biofilm activities of the cell-free culture supernatant (CFCS) of Limosilactobacillus reuteri against normal and stressed Salmonella Typhimurium in seawater microcosms over four years. The CFCS exhibited minimum inhibitory concentrations (MIC) ranging from 16.66% to 30% under acidic conditions, whereas stressed strains showed increased resistance, with MIC reaching up to 60% at neutral pH. Antioxidant activity reached 38% (DPPH assay), and CFCS significantly reduced biofilm formation and bacterial adhesion by up to 52% on the fish cell line (SAF-1). Additionally, L. reuteri CFCS modulated the expression of genes related to oxidative stress (cat, sod, gr) and immune response (il1b, il6, il8). These findings highlight the potential of L. reuteri CFCS as a natural antimicrobial and anti-virulence agent in marine aquaculture, helping to address antibiotic resistance issues.

Canine distemper (CD) is a severe infectious disease of dogs caused by the Canine Distemper Virus (CDV), a member of the genus Morbillivirus. This study aimed to investigate the circulation of CDV in dogs housed in two public kennels located in Belém in the Amazon region of Brazil. Fecal and rectal swab samples were collected between March 2019 and April, 2020. A one-step RT-PCR was initially standardized for CDV detection in fecal samples. Positive strains were partially sequenced using Sanger sequencing. A prevalence rate of 23.6% was observed, with 18.4% in healthy dogs and 46.7% in dogs with diarrhea. Phylogenetic analysis revealed that the samples were closely related to European strains and demonstrated the circulation of Brazilian strains belonging to the Europe 1/South America 1 lineage. This investigation successfully established a CDV diagnostic technique using RT-PCR in blood, feces, and urine samples. This study also verified the circulation of the virus in dogs from public kennels in an important city in the Brazilian Amazon.

Wild birds are an important source of viral infection since it is considered a reservoir for a number of viruses, such as Paramyxovirus and a range of Gammacoronavirus and Deltacoronavirus. Avian paramyxovirus 1 (APMV-1), the causative agent of Newcastle Disease (ND), poses significant threats to both wild and domestic avian populations. Gammacoronaviruses, such as the Infectious Bronchitis Virus (IBV), primarily affect poultry, leading to respiratory, enteric, reproductive, and neurological disorders. The aim of this study was to monitor the presence of paramyxovirus and coronaviruses in shorebirds in the middle coast of southern Brazil, between May and December of 2023, by analyzing fecal samples for the presence of viral genome. Two hundred and eighty-nine fresh fecal samples were collected monthly between May and December of 2023 in the middle coast of Rio Grande do Sul state, Brazil. RNA was extracted from the samples following the protocol of PREVIR and cDNA was synthesized. All samples were screened for APMV-1 M gene by qRT-PCR and for the RdRp gene of coronavirus by nPCR. Positive samples were confirmed by Sanger Sequencing. Five samples out of 289 (1.73%/100%) contained APMV-1 RNA, while all samples were negative for coronavirus RNA. APMV-1 RNA was detected in feces of the American Oystercatcher (Haematopus palliatus) (1/5) and Kelp Gulls (Larus dominicanus) (2/5). To our knowledge, this is the first report of APMV-1 infection in American Oystercatcher and Kelp Gulls. Although at a low frequency, we demonstrate the presence of APMV-1 in the coast of Brazil, posing a risk of infections in an area in South Brazil which is visited by thousands of wild birds each year during migration. These studies should continue in order to keep surveillance and anticipate outbreaks which could impact both wild and domestic birds health.