Microbial pathogenesis最新文献

This study aims to isolate and identify both diseased and healthy fish pathogens of Ctenopharyngodon idella, Labeo rohita and Oreochromis niloticus and assess their antibacterial and biofilm supressing activities against fish pathogens. It explores their potential to inhibit and degrade biofilms, serving as an alternative to antibiotics in aquaculture while enhancing fish health and disease resistance. Furthermore, the research endeavors to assess the biofilm degradation potential of antibiotics and probiotics, both individually and in combination. The biofilm-forming potential of pathogens was assessed both qualitatively and quantitatively using the Congo red assay, cover slip, and test tube methods. Additionally, genomic sequencing through 16S rRNA ribotyping revealed the species level identification of four pathogenic and twelve probiotic strains. Three pathogens, Staphylococcus sciuri, Pseudomonas aeruginosa, and Staphylococcus xylosus, showed significant biofilm formation at day 5, while the pathogen Niallia circulans expressed maximum biofilm formation on day 7. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of antibiotics were evaluated against pathogenic strains. Antibiotic susceptibility testing revealed significant inhibition zones. MIC and MBC values ranged from 0.10 mg/ml to 85.00 mg/ml, with the agar well and disk diffusion methods demonstrating strong inhibitory effects against the pathogenic strains. Notably, fish probiotics either alone or in combination with antibiotics exhibited significant inhibition and anti-biofouling activity across three different concentrations (1/2 MIC, 1MIC, 2XMIC). The biofilm eradication values were statistically significant (p < 0.005). The findings affirm the effectiveness of the antibiotics (ampicillin, levofloxacin, kanamycin and oxytetracycline) and probiotics (Bacullus altitudinis, Bacillus pumilus, Mammaliicoccus sciuri) employed in preventing and dispersing biofilms formed by isolated fish pathogens (S. sciuri, P. aeruginosa and N. circulans). The current study explores the use of probiotics to enhance fish immunity, reduce disease risk without promoting antibiotic resistance, and disrupt pathogenic biofilms to control infections. Unlike antibiotics, probiotics are biodegradable and eco-friendly, minimizing harm to aquatic ecosystems and beneficial microbes.

Bacterial diseases are the most common diseases in aquaculture worldwide, resulting in severe economic losses in the aquaculture industry. However, bacterial pathogens usually lead to non-specific clinical symptoms and are difficult to diagnose in clinical samples. Therefore, specific, sensitive, and time-saving detection methods are crucial for earlier prevention and accurate treatment of bacterial pathogens. This study developed a TaqMan probe-based multiplex real-time PCR method for simultaneous detection and quantification of four bacterial pathogens, including Edwardsiella piscicida, Photobacterium damselae subsp. piscicida, Vibrio rotiferianus, and Pseudomonas fluorescens. The conserved regions of the intra-species and the specific regions of the inter-species were targeted using specific primers and Taqman probes to ensure specificity. Sensitivity analysis showed that the four bacteria were simultaneously detected in the multiplex real-time PCR assay, with detection limits of 32-76 copies/reaction, which is 100 times higher than that of the conventional PCR assay. Furthermore, the assay had good reproducibility, with intra- and inter-group coefficients of variation below 1%. A total of 63 clinical samples were analyzed using this established assay, of which either single or mixed infection samples could be correctly detected. These findings indicate that this multiplex qPCR assay can serve as a quick, specific, sensitive diagnostic tool for E. piscicida, P. damselae subsp. piscicida, V. rotiferianus, and P. fluorescens detection, thus can be utilized to monitor these bacteria in single or co-infected clinical samples.

Pseudomonas putida is one of the emerging pathogens responsible causing mastitis in lactating animals. This study investigated the prevalence, antimicrobial resistance (AMR), genetic diversity and virulence factor genes (VFGs) to highlight the pathogenic potentials of P. putida strains isolated from milk, feces and farm soil of bovine clinical mastitis (CM). A total of 110 samples were collected and analyzed, revealing an overall prevalence of P. putida in dairy farms at 40.90%, with specific prevalence rates of 42.22% in milk, 26.67% in feces, and 31.11% in farm soil. In vitro antimicrobial assays demonstrated that 76.0% P. putida isolates exhibited multidrug resistance (MDR, resistance to ≥ 3 antibiotics), particularly showing high resistance to oxacillin, ampicillin, nalidixic acid, and aztreonam. Conversely, P. putida isolates showed the highest susceptibility against imipenem. The genome analysis of three MDR P. putida strains 11CM-M1 (milk), 11CM-F1 (feces) and 11CM-S1 (farm soil), showed a close evolutionary relationship with different strains of Pseudomonas spp. isolated from bovine mastitis milk and feces samples, human stool, and the hospital environment. The assembled genomes of three P. putida strains encoded nine antibiotic resistance genes (ARGs), 36 VFGs, and 367 metabolic subsystems, highlighting a complex functional profile and potential for pathogenicity. The detailed analysis of these ARGs and VFGs demonstrated that P. putida strains employ distinct mechanisms of resistance (e.g., efflux pumps), biofilm formation, and virulence factors, including adhesins, secreted toxins, and lipopolysaccharides, which contribute to their pathogenic potential. Given the lack of reports linking P. putida strains to bovine mastitis in Bangladesh, the increasing trend of AMR, along with the presence of significant ARGs and VFGs in the studied strains, underscores the need for more intensive research, including animal model experiment, to better elucidate the pathogenesis and inform treatment decisions for mastitis in dairy animals.

Background: Multidrug-resistant Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) are emerging in large numbers, while the rapid development of antimicrobial nanomaterials offers new opportunities to combat bacterial infections and antimicrobial resistance OBJECTIVES: We employed the nanomaterial MIL-101(Fe) as a carrier loaded with Patchouli alcohol (PA) to form the complex MIL-101(Fe)-PA. and to investigate the inhibitory activity of MIL-101(Fe)-PA against S. aureus and E. coli.

Methods: According to the literature,we prepared MIL-101(Fe)-PA by solvent method. Characterization of MIL-101(Fe)-PA was carried out using scanning electron microscopy(SEM) , Fourier transform infrared(FT-IR) spectroscopy,X-ray diffractometer (XRD) and Brunauer-Emmett-Teller (BET) adsorption analysis. In the bacteriostatic experiments,its bacteriostatic effect was investigated by Minimal inhibitory concentration (MIC) experiments,cell proliferation,and growth curves of bacteria. Then its cytotoxicity was explored by cytotoxicity experiments.

Results: The characterization results indicated that we successfully prepared the complex MIL-101(Fe)-PA,which showed significant bacteriostatic effects against S. aureus and E. coli at 2 mg/mL. The inhibitory effect was stronger than that of MIL-101(Fe) as well as PA.

Conclusion: It shows that MIL-101(Fe)-PA has excellent inhibitory effect on S. aureus and E. coli.

Mangroves are crucial for supporting coastal communities, benefiting both humans and animals. Their intricate root systems grasp the soil, mitigating erosion and dampening wave impact. As a result, they shield and fortify shorelines that would otherwise erode. This study focuses on the isolation of endophytic bacteria from the stem of Bruguiera gymnorrhiza. Molecular analysis using 16S rDNA gene sequencing identified the isolate as Bacillus subtilis (BG1). Its hydrolytic enzyme production capabilities were assessed, revealing its ability to produce cellulase, amylase, protease and L-asparaginase. The isolate also demonstrated various plant growth promoting traits including ammonia production, indole 3- acetic (IAA) production, hydrogen cyanide (HCN) production, phosphate solubilization, and ACC deaminase activity. IAA and organic acid production were quantified using Liquid Chromatography - Mass Spectrometry (LC-MS/MS), with B. subtilis producing 86.32 ± 0.64 μg mL^-1 of IAA, peaking at a retention time of 6.8 minutes. The endophyte also produced two different organic acids during phosphate solubilization with malic acid been the most abundant (398.79 ± 2.58 μg mL^-1). Additionally, B. subtilis was able to form biofilm and exhibited drug resistance towards Cefixime (5 μg). Biofilm was characterized using Fourier transform infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). Invitro antagonist studies demonstrated the significant effectiveness of B. subtilis against two pathogens, Staphylococcus aureus and Streptococcus mutans. This is the first study to successfully isolate and identify endophytic bacteria from B. gymnorrhiza, highlighting its plant growth promoting traits, biofilm forming potential, and antibacterial capabilities.