bioRxiv Science⌕ Search

Biology subjects

Barcellos, I. S.

Publications and source records attributed to Barcellos, I. S..

2 recordsLinked to original sources
bioRxiv2026

Virulence and antimicrobial resistance features among clades of Escherichia coli ST131 strains causing community-acquired urinary tract infection in Rio de Janeiro, Brazil

Urinary tract infection (UTI) is one of the most common community-acquired bacterial infections mainly caused by extraintestinal pathogenic Escherichia coli (ExPEC) strains. The high-risk Escherichia coli ST131 clone is a major global cause of this disease. The lineage rapid dissemination is associated to multidrug resistance (MDR), production of extended-spectrum beta-lactamase (ESBL), and multiple virulence-associated genes. Although we lack information about ExPEC high-risk clones in Latin America, we recently reported an increase in ST131 dissemination in Rio de Janeiro from 2015 to 2019. The present study aims to characterize virulence and resistance molecular and phenotypic features that may contribute to dissemination of E. coli ST131 in Rio de Janeiro, Brazil. We assessed a 133 E. coli ST131 strains collection obtained from urine of outpatients with suspected UTI, in 2019. We determined antimicrobial susceptibility, fluoroquinolones resistance genes, virulence factors associated genes and biofilm production of all strains and analyzed the frequencies by each clade or subclade. A higher incidence of women (92%) and elderly (65%) subjects was observed. Overall resistance to first- and second-line treatment for UTI antimicrobials ampicillin, ciprofloxacin and sulfamethoxazole-trimethoprim was detected in high rates (40%), with a major impact of subclade C2 strains that were resistant to almost all antimicrobials tested, 52% carry ESBL and 66% of strains harbor the aac(6)-Ib-cr ciprpofloxacin resistance gene. Clade B and subclade C2 showed higher virulence scores among the other clades. They present unique virulence profiles characterized by the presence of papGIII, sfa/focDE, and especially ibeA genes in clade B, and the afa/DrBC, papGII, hlyA, cnf1 genes in subclade C2. Over 50% of our strains are biofilm producers, characterized by weak (24%) and strong producers (32%). ESBL and MDR strains harbor mainly papA, papGII, hlyA, cnf1 and kpsMTII genes that plays a key role in ST131 colonization. Subclade C1 is the major biofilm producer (78%), despite its lower virulence score. We also detected higher incidence of papA (27%), hlyA (19%) genes and the RPAI(malX) marker (84%) in biofilm producer strains with a statistical association of sfa/focDE gene (9%). We can infer that Clade C strains might be responsible for ST131 dissemination and persistence in Rio de Janeiro.

microbiology↗
bioRxiv2026

ADHESION, BIOFILM, AND INVASION: INVESTIGATING THE VIRULENCE MECHANISMS OF Prevotella spp.

The Prevotella genus are strict anaerobic organisms associated with opportunistic infections in the vaginal, oral, and gastrointestinal cavities. During infection, virulence mechanisms such as adhesion to host tissues, invasion of cells and connective tissue, and evasion of the immune system are essential for bacterial establishment and host persistence. In the present study, we investigated the adhesion to human extracellular matrix proteins, biofilm formation, Matrigel invasion, and plasminogen activation of strains from the Prevotella species, including P. intermedia, P. melaninogenica, and P. nigrescens. The bacterial adhesion capacity was quantified by the interaction of these bacteria with extracellular matrix proteins, including fibronectin, collagen type IV, collagen type I, laminin type 1, and Matrigel, previously immobilized on glass slides. P. intermedia and P. nigrescens demonstrated adhesion to fibronectin, type IV collagen, and Matrigel. P. melaninogenica did not adhere to the substrates under the study conditions. To identify ligands in Prevotella and Fusobacterium, outer membrane protein extracts were purified from P. intermedia, P. nigrescens, and F. nucleatum and subjected to affinity chromatography using NHS-activated Sepharose columns containing immobilized laminin, fibronectin, and type IV and type I collagen. Eluted fractions containing potential ligands were sent for mass spectrometry analysis. In P. intermedia, six proteins were identified as potential laminin adhesins and 15 as potential type IV collagen adhesins. In P. nigrescens, five proteins were identified as potential laminin adhesins and three as potential type IV collagen adhesins. Biofilm experiments were also conducted in the presence and absence of Matrigel. Biofilm formation was reduced in the presence of this substrate in P. intermedia and P. melaninogenica, while no significant difference was observed in the other species tested. To analyze the biofilm architecture, scanning electron microscopy was performed. It was observed that, in the presence of Matrigel, the biofilm surface of the analyzed species was altered. P. melaninogenica did not form biofilm on the glass surface used for SEM. A transwell invasion assay was performed for all Prevotella species. It was observed that only P. melaninogenica was capable of crossing the Matrigel layer. Matrigel degradation assays using SDS-PAGE showed that P. melaninogenica degrade matrix proteins and plasminogen. To understand the interaction between species and plasminogen, a plasminogen activation kinetic assay was conducted, in which only P. melaninogenica activated this molecule, likely utilizing this strategy to destroy tissues. Understanding the mechanisms involved in virulence may help develop new strategies to prevent periodontitis and biofilm formation in the gingival sulcus.

microbiology↗