Type I fimbriae subunit fimA enhances Escherichia coli biofilm formation but affects L-threonine carbon distribution

Multidrug-Resistant Uropathogens in Companion Animals: A Comprehensive Study from Clinical Cases and a Genomic Analysis of a CTX-M-14-Producing Escherichia coli ST354, a Leading Cause of Urinary Tract Infections

Urinary tract infections (UTIs) are common in small animals, posing significant clinical challenges due to their recurrence and discomfort. This study investigated the bacterial causes and antimicrobial resistance patterns of UTIs in dogs and cats presented to an important Veterinary Teaching Hospital in São Paulo, Brazil, the largest city in Latin America. Samples were collected from 31 dogs and 9 cats via ultrasound-guided cystocentesis. Bacterial cultures were performed, species identification was accomplished with matrix-assisted laser desorption ionization-time of flight mass spectrometry, and antimicrobial susceptibility testing was done using the Kirby-Bauer method. Escherichia coli was the most frequently isolated pathogen, accounting for 27.9% of cases, followed by Staphylococcus pseudintermedius, Proteus mirabilis, and Klebsiella pneumoniae. Ampicillin resistance was observed in 70.4% of enterobacteria, with many E. coli strains exhibiting multidrug resistance. Whole-genome sequencing of an extended-spectrum beta-lactamase-producing uropathogenic Escherichia coli strain from a feline patient was performed; it was identified as ST354, a leading cause of UTIs worldwide in humans and animals, carrying the blaCTX-M-14 gene and other resistance determinants. Phylogenetic analysis indicated genetic proximity between this strain and others from Brazilian poultry and environmental sources. These findings emphasize the need for antimicrobial resistance surveillance in veterinary UTIs and advocate for stricter antibiotic stewardship to inform diagnostic and therapeutic approaches within a One Health perspective.

Whole Genome Sequencing and Comparative Genomics Analysis of Goat-Derived Klebsiella oxytoca

Background: This research aims to enhance the genomic database of Klebsiella oxytoca by identifying virulence genes through the whole genome sequencing and comparative analysis of a goat-derived K. oxytoca (KOHN1) strain, while clarifying the relationship between its genetic evolution and virulence, ultimately providing a theoretical foundation for clinical prevention and diagnosis. Methods: Third-generation Oxford Nanopore Technologies (ONT) sequencing and second-generation Illumina sequencing were used to sequence the strain and analyze the database annotations. Screening for 10 virulence genes was conducted using PCR. Comparative genomic analyses of the strain KOHN1 with four human-derived K. oxytoca model strains were performed using collinearity analysis, taxonomy classification through ANI analysis, and gene function family analysis. Results: The genome size of the KOHN1 strain was 5,817,806 bp, and the GC content was 55.14%. It contained 5227 predicted coding genes, including 25 rRNA genes, 85 tRNA genes, and 53 sRNA genes. A total of 14 type VI secretion system effector proteins and 146 virulence factor-related genes were annotated. Additionally, eight virulence genes-fimA, fimH, entB, mrkD, clpV, rmpA, vgrG, and hcp-were detected through PCR identification. The strain has 448 drug resistance genes, mainly against β-lactams and fosfomycins. Comparative genomic analysis indicated that its closest relation is the human isolate ASM338647. Conclusions: In this study, the whole genome sequence of a goat-derived K. oxytoca (KOHN1) strain was obtained, revealing its evolutionary relationship with domestic and foreign isolates and providing a reference for future studies on the mechanisms of antimicrobial resistance and the pathogenicity of K. oxytoca.

Effects of Heat-Killed Probiotic Strains on Biofilm Formation, Transcription of Virulence-Associated Genes, and Prevention of UTIs in Mice

Urinary tract infections (UTIs) pose a substantial healthcare challenge, exacerbated by the biofilm-forming abilities and antibiotic resistance of uropathogens. This study investigated the inhibition of biofilm formation (anti-biofilm) and dispersion of pre-established biofilm properties of 18 heat-killed probiotics and their supernatants against four antibiotic-resistant uropathogens: UPEC, Klebsiella pneumoniae (KP), Methicillin-resistant Escherichia coli (MREC), and Methicillin-resistant Staphylococcus pseudintermedius (MRSP). Supernatants from 14 probiotic strains significantly (P < 0.001) inhibited UPEC biofilm formation, reducing it by 20-80%, and also showed promise in removing existing biofilms by 10-60% (P < 0.001). Eight strains significantly (P < 0.05 to < 0.001) inhibited MREC biofilm formation, with four strains achieving 50-80% dispersion. Seventeen strains of heat-killed probiotics directly inhibited UPEC biofilm formation by 10-60% (P < 0.05 to < 0.001), but were less effective against MREC and MRSP (10-50% reduction; P < 0.05 to < 0.001) and had limited impact on KP (10% reduction; P < 0.05 to < 0.001). Notably, heat-killed probiotic like LGA, LGC, LGD, TP-8, and TP-4 showed the most significant inhibitory and dispersion of biofilm activity. RT-qPCR analysis further revealed these inactivated probiotics downregulated genes associated with pili and biofilm formation (fimA, csgA) and upregulated genes linked to quorum sensing (luxS, qseBC, sdiA). Therefore, these findings suggest that paraprobiotic treatment could inhibit the formation of pili and biofilms and promote biofilm dispersion. In an animal model, mice given paraprobiotic formulations I (16 strains) and II (a specific mixture) for 2 weeks showed reduced urinary bacterial load (P < 0.05). Paraprobiotic I notably reduced morbidity from bacteriuria (> 105 CFU/ml) by 5 to 30% within the first 5 days post-infection compared to placebo. These findings highlight the potential of specific heat-killed probiotics in combating biofilms and preventing UTIs.

Microbial Biofilm Inhibition Using Magnetic Cross-Linked Polyphenol Oxidase Aggregates

Microbial biofilm accumulation poses a serious threat to the environment, presents significant challenges to different industries, and exhibits a large impact on public health. Since there has not been a conclusive answer found despite various efforts, the potential green and economical methods are being focused on, particularly the innovative approaches that employ biochemical agents. In the present study, we propose a bio-nanotechnological method using magnetic cross-linked polyphenol oxidase aggregates (PPO m-CLEA) for inhibition of microbial biofilm including multidrug resistant bacteria. Free PPO solution showed only 55-60% biofilm inhibition, whereas m-CLEA showed 70-75% inhibition, as confirmed through microscopic techniques. The carbohydrate and protein contents in biofilm extracellular polymeric substances (EPSs) were reduced significantly. The m-CLEA demonstrated reusability up to 5 cycles with consistent efficiency in biofilm inhibition. Computational work was also done where molecular docking of PPO with microbial proteins associated with biofilm formation was conducted, resulting in favorable binding scores and inter-residual interactions. Overall, both in vitro and in silico results suggest that PPO interferes with microbial cell attachment and EPS formation, thereby preventing biofilm colonization.

Type 1 fimbriae-mediated collective protection against type 6 secretion system attacks

Bacterial competition may rely on secretion systems such as the type 6 secretion system (T6SS), which punctures and releases toxic molecules into neighboring cells. To subsist, bacterial targets must counteract the threats posed by T6SS-positive competitors. In this study, we used a comprehensive genome-wide high-throughput screening approach to investigate the dynamics of interbacterial competition. Our primary goal was to identify deletion mutants within the well-characterized E. coli K-12 single-gene deletion library, the Keio collection, that demonstrated resistance to T6SS-mediated killing by the enteropathogenic bacterium Cronobacter malonaticus. We identified 49 potential mutants conferring resistance to T6SS and focused our interest on a deletion mutant (∆fimE) exhibiting enhanced expression of type 1 fimbriae. We demonstrated that the presence of type 1 fimbriae leads to the formation of microcolonies and thus protects against T6SS-mediated assaults. Collectively, our study demonstrated that adhesive structures such as type 1 fimbriae confer collective protective behavior against T6SS attacks.IMPORTANCEType 6 secretion systems (T6SS) are molecular weapons employed by gram-negative bacteria to eliminate neighboring microbes. T6SS plays a pivotal role as a virulence factor, enabling pathogenic gram-negative bacteria to compete with the established communities to colonize hosts and induce infections. Gaining a deeper understanding of bacterial interactions will allow the development of strategies to control the action of systems such as the T6SS that can manipulate bacterial communities. In this context, we demonstrate that bacteria targeted by T6SS attacks from the enteric pathogen Cronobacter malonaticus, which poses a significant threat to infants, can develop a collective protective mechanism centered on the production of type I fimbriae. These adhesive structures promote the aggregation of bacterial preys and the formation of microcolonies, which protect the cells from T6SS attacks.