Brazilian Journal of Microbiology最新文献

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.

Flucytosine (FC) is currently used as an antifungal drug for the treatment of infectious diseases. However, due to the development of drug resistance, the monotherapy of FC is limited. Recently, nanoliposomes have been studied as promising approaches to overcome microbial resistance. In this study, we encapsulate FC in the nanoliposomes and investigate their physicochemical properties as well as antifungal activities against Candida glabrata and Candida albicans in-vitro. Various liposomal formulations of FC were prepared based on the modified freeze-drying of a monophase solution method. The nanoliposomes were characterized in terms of size, zeta potential, transmission electron microscopy image, encapsulation efficiency, stability, release, crystallography, and cytotoxicity. Also, the minimum inhibitory concentration and minimum fungicidal concentration were determined against C. glabrata and C. albicans. The size and zeta potential of the selected nanoliposomes were 147.33 ± 23.25 nm and - 31.20 ± 9.05 mV, respectively. Encapsulation efficiency was 46.7 ± 7.5% in the selected formulation. TEM results revealed that the nanoliposomes were nano-sized and spherical. Release results indicated that the nanoliposomes had a slow-release rate of FC. The fungal eradication of nanoliposomal FC was at least two times higher than that of the free drug for C. glabrata and C. albicans. Cytotoxicity studies demonstrated no significant toxicity at effective concentrations of nanoliposomal FC. The stability of the nano-formulation was temperature-dependent, and the refrigerator showed the best condition for long-term storage. Nanoliposomal FC prepared using the modified freeze-drying of a monophase solution method seems promising and may be used to overcome the fungal resistance relative to FC.

To improve the direct diagnosis of bovine tuberculosis (bTB) in lesions from carcasses condemned at slaughterhouses - the primary method for identifying infected farms within the Surveillance System - two qPCR assays were evaluated against the gold standard: culture and identification of Mycobacterium bovis. A total of 167 lesion samples were collected by inspection services in Mato Grosso and Santa Catarina. Samples were homogenized and analyzed using culture and qPCR targeting the IS1081 sequence (for the M. tuberculosis complex) and the RD4 region (specific to M. bovis). Both qPCR assays demonstrated acceptable sensitivity and specificity, confirming the diagnostic value of these targets. The IS1081 qPCR showed a sensitivity of 0.80 [95% CI: 0.69-0.89] and specificity of 0.79 [95% CI: 0.70-0.87]. The RD4 qPCR yielded a sensitivity of 0.74 [95% CI: 0.61-0.84] and specificity of 0.84 [95% CI: 0.76-0.91]. Agreement between the two qPCR assays was high (K = 0.89 [95% CI: 0.82-0.96]). When using the parallel results of culture and IS1081 qPCR as gold standard, the RD4 assay achieved a sensitivity of 0.74 [95% CI: 0.64-0.83] and specificity of 1.00 [95% CI: 0.96-1.00]. In conclusion, both assays produced comparable results. The RD4 qPCR, due to its specificity for M. bovis, shows promise as a replacement for classical bacteriology and conventional PCR in bTB surveillance, offering operational advantages.

Chickpea (Cicer arietinum L.) is a vital legume crop, but its productivity is often limited by poor soil fertility. This study aimed to assess the nodulation efficacy and plant growth-enhancing activities of six Mesorhizobium spp. strains in the chickpea cultivar Pusa 362 through the Leonard jar experiment and field trial. The strains, including two strains from ICRISAT (reference strains), were tested for solubilization of phosphate, potassium, and zinc, and production of Indole-3-Acetic Acid (IAA). Strain C5 excelled in phosphate solubilization (61.40 µg/ml), while C7 was superior in potassium (26.10 µg/ml) and zinc phosphate (69.15 µg/ml) solubilization; C17 showed the highest IAA production (25.75 µg/ml). In the Leonard jar experiment, inoculation of strains M. ciceri C5 and M. helmanticense C17 exhibited the highest nodule number and root dry weight, while treatments with M. ciceri C5 and M. helmanticense C7 inoculation recorded the maximum nodule dry weight and shoot dry weight. Field trials indicated significant improvements in nodulation, biomass, and nitrogen content in chickpeas inoculated with these strains. Treatment with strain C7 led to the highest increase in nodule number and root dry weight over the control, while strain C5 inoculation recorded maximum grain yield. Correlation analysis showed positive relationships between yield and several growth parameters. Nodule occupancy tests revealed that strain C7 had the highest occupancy (32.98%), followed by C5 (31.92%), indicating superior nodulation competitiveness under field conditions. These results suggest that inoculation with specific Mesorhizobium strains can significantly enhance chickpea productivity through improved nodulation and nitrogen fixation.

Salmonellosis poses a significant public health threat, potentially leading to severe complications, ranging from enteritis to life-threatening septicemia. Salmonella enterica ssp. enterica serovar Typhimurium has the ability to translocate from the intestine to the liver via the hepatic portal system, causing severe lesions in the organ. The development of new treatment strategies is crucial, due to clinical burden of this infection. In this context, probiotics have emerged as a promising therapeutic avenue due to their multifaceted mechanisms of action. The aim of this study was to investigate the probiotic potential of two strains of Limosilactobacillus reuteri (UN34 and UN41) in a murine model of salmonellosis. Although both strains demonstrated in vitro characteristics indicative of potential probiotics, only the UN41 strain improved the survival rate of mice infected with S. Typhimurium, highlighting that the probiotic effect is strain-specific. In the in vivo model, administration of UN41 also attenuated neutrophilic infiltration, reduced bacterial translocation to the liver, lowered AST levels, and mitigated liver injury. These findings underscore the potential of L. reuteri UN41 as a promising probiotic candidate for mitigating the impact of salmonellosis.