Brazilian Journal of Microbiology最新文献

Background: Bovine tuberculosis (bTB) is a chronic infectious disease caused primarily by infection with M. bovis, which belongs to the Mycobacterium tuberculosis complex. There are different diagnostic tests for the diagnosis of bovine tuberculosis, among which, determination of biomarkers plays a significant role. However, the biomarkers for the diagnosis of bTB in naturally infected cattle are limited.

Methods: In the present study, the gene expression profile of host immune-related genes (MCP-1, MMP-9, CCR5, iNOS, IFNγ, TNFα, and IL-23A) was studied. The aim of the study was to evaluate this set of immune-related genes for their potential use as diagnostic biomarkers of bTB infection in cattle. A total of 40 HF cross-breed cattle were grouped into two groups uninfected, and bTB infected, on the basis of results obtained by CITT, IS6100 PCR. The PBMCs from both groups were cultured and stimulated in vitro with bovine tuberculin PPD.

Results: In the results, the mRNAs (MCP-1, MMP-9, CCR5, iNOS, IFNγ, TNFα and IL-23A) were upregulated in bTB-positive animals relative to negative controls. The transcripts can discriminate between bTB-positives and uninfected controls, with AUC ranging from 0.8 to 1. The targeted genes showed promising results and further studies are needed to explore the potential of these highly expressed transcripts as the potential biomarker of bTB in naturally infected cattle.

Pseudomonas aeruginosa causes persistent infections largely through biofilm formation. In polymicrobial environments, it forms dual-species biofilms in which microbial interactions influence structure, virulence, and antibiotic response. Sub-inhibitory antibiotic concentrations may modulate these behaviors differently in single- versus dual-species settings. This study evaluated the effect of Tobramycin at ½ minimal inhibitory concentration (MIC) on biofilm formation and virulence gene expression (toxA, lipA) in P. aeruginosa under single- and dual-species biofilm conditions. Clinical isolates were tested for Tobramycin susceptibility, MIC determination, and biofilm production. Biofilm biomass was quantified by microtiter assays, and gene expression was assessed by qRT-PCR. Overall, 78% of isolates were resistant to Tobramycin, with most MICs at 32 µg/ml (37.3%) and 1024 µg/ml (11.8%). All isolates formed biofilms, predominantly at moderate levels (63.08%). Tobramycin at ½ MIC significantly reduced biofilm biomass in both single-species (median OD₆₃₀: 0.128 ± 0.08 to 0.077 ± 0.09; p < 0.0001) and dual-species biofilms (0.158 ± 0.037 to 0.106 ± 0.041; p = 0.0005). toxA expression decreased markedly in dual-species biofilms compared to single-species (0.003 ± 0.0002 vs. 0.05 ± 0.009; p = 0.0003), while lipA expression showed a nonsignificant decline. In conclusion, sub-MIC Tobramycin reduces P. aeruginosa biofilm biomass and downregulates virulence genes, with more pronounced effects in dual-species biofilms. These findings highlight the potential impact of low-level antibiotic exposure on biofilm-associated pathogenicity and may inform optimized dosing strategies for chronic polymicrobial infections.

Objective: The primary objective of this study was to assess the prevalence of Bordetella bronchiseptica infection in dogs of West Azerbaijan province, Iran through molecular techniques.

Methods: A total of 100 blood samples from dogs were collected, and information regarding their age, sex, breed, housing conditions, and Presence or absence of respiratory diseases signs was recorded. The identification of positive samples was accomplished through PCR and sequencing, with subsequent analysis of the gene sequences conducted using Oligo7 software.

Results: The results revealed that 17 of the blood samples tested positive for B. bronchiseptica. The highest rate of infection was recorded in brachycephalic dogs, at 41.17%, whereas the lowest rate was found in non-brachycephalic dogs, at 4.54%. Data analysis indicated that age, sex, and housing conditions did not have a significant association with B. bronchiseptica infection. However, the presence or absence of respiratory disease signs demonstrated a significant correlation with infection status. This study highlights a notable prevalence of B. bronchiseptica infection among dogs, suggesting that both kenneled and pet dogs may present a risk factor for human infections with B. bronchiseptica.

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.

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.

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 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.