The XadA Trimeric Autotransporter Adhesins in Xylella fastidiosa Differentially Contribute to Cell Aggregation, Biofilm Formation, Insect Transmission and Virulence to Plants.

Surface adhesion strategies are widely employed by bacterial pathogens during establishment and systemic spread in their host. A variety of cell-surface appendages such as pili, fimbriae, and afimbrial adhesins are involved in these processes. The phytopathogen Xylella fastidiosa employs several of these structures for efficient colonization of its insect and plant hosts. Among the adhesins encoded in the X. fastidiosa genome, three afimbrial adhesins, XadA1, Hsf/XadA2, and XadA3, are predicted to be trimeric autotransporters with a C-terminal YadA-anchor membrane domain. We analyzed the individual contributions of XadA1, XadA2, and XadA3 to various cellular behaviors both in vitro and in vivo. Using isogenic X. fastidiosa mutants, we found that cell-cell aggregation and biofilm formation were severely impaired in the absence of XadA3. No significant reduction of cell-surface attachment was found with any mutant under flow conditions. Acquisition by insect vectors and transmission to grapevines were reduced in the XadA3 deletion mutant. While the XadA3 mutant was hypervirulent in grapevines, XadA1 or XadA2 deletion mutants conferred lower disease severity than the wild-type strain. This insight of the importance of these adhesive proteins and their individual contributions to different aspects of X. fastidiosa biology should guide new approaches to reduce pathogen transmission and disease development. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Detection of antimicrobial resistance genes in beta-lactamase- and carbapenemase-producing Klebsiella pneumoniae by patient surveillance cultures at an intensive care unit in Rio de Janeiro, Brazil / Detecção de genes de resistência a antimicrobianos em Klebsiella pneumoniae produtoras de betalactamases e carbapenemases por culturas de vigilância de pacientes em uma unidade de terapia intensiva no Rio de Janeiro, Brasil

ABSTRACT Introduction: The increasing incidence of multi-resistant microorganisms has been considered a public health problem. One of the routines included in hospital practice is the screening of colonized and/or infected patients. Objective: The aim of this study was to evaluate the genetic variability and clonal relationships of extended-spectrum beta-lactamase (ESBL)-producing K. pneumoniae, from surveillance cultures, at an intensive care unit, in Rio de Janeiro, Brazil. Material and methods: Seventy K. pneumoniae isolates were obtained from rectal swabs (March 2013 to March 2014). Antimicrobial susceptibility was assessed by VITEK 2 System. Resistant genes blaSHV, blaTEM, blaOXA-1, blaKPC, blaOXA-48, blaCTX-M-15, blaVIM, blaIMP and blaNDM were investigated by polymerase chain reaction (PCR); genetic diversity, by Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR). Results: Strains showed high resistance rates to cefepime (94%), ceftazidime (96%), ertapenem (61%), imipenem (54%) meropenem (43%) and ciprofloxacin (69%). The most prevalent genes were blaSHV (69%), blaTEM (63%), blaOXA-1 (60%), blaKPC (57%), blaCTX-M-15 (47%), blaOXA-48 (16%). Genes blaVIM, blaIMP and blaNDM were not detected. Twenty nine profiles of resistance genes were observed, with 23% carrying at least five genes. A great genetic diversity (68 ERIC profiles) was also observed among the strains. Conclusion: Although no clonal relationship was observed within the isolates, this study revealed alarming data on the antimicrobial resistance deficiently monitored for preventive purposes in Brazil. Our data allow us to conclude that the inclusion of surveillance cultures in health facilities is a recommended strategy aiming particularly at preventing the spread of resistance genes in the hospital environment and, consequently, reducing morbidity and mortality.

RESUMO Introdução: O aumento da incidência de microrganismos multirresistentes é considerado um dos principais problemas de saúde pública. Uma das rotinas incluídas na prática hospitalar é a busca de pacientes colonizados e/ou infectados. Objetivo: Avaliar a variabilidade genética e as relações clonais de K. pneumoniae produtoras de betalactamases de espectro estendido (ESBL) em culturas de vigilância de unidade de terapia intensiva (UTI) no Rio de Janeiro, Brasil. Materiais e métodos: Setenta isolados obtidos a partir de swab retal, (março/2013 a março/2014). O perfil de suscetibilidade a antibióticos foi avaliado pelo sistema VITEK 2. Foram pesquisados os genes de resistência: blaSHV, blaTEM, blaOXA-1, blaKPC, blaOXA-48, blaCTX-M-15, blaVIM, blaIMP e blaNDM pela reação em cadeia da polimerase (PCR). A diversidade genética foi avaliada por Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR). Resultados: Foram detectados altos percentuais de resistência a cefepime (94%), ceftazidima (96%), ertapenem (61%), imipenem (54%) meropenem (43%) e ciprofloxacino (69%). Os genes prevalentes foram: blaSHV (69%), blaTEM (63%), blaOXA-1 (60%), blaKPC (57%), blaCTX-M-15 (47%), blaOXA-48 (16%). Os genes blaVIM, blaIMP e blaNDM não foram detectados. Foram observados 29 perfis em relação aos genes de resistência, com 23% apresentando pelo menos cinco genes. Uma grande diversidade genética (68 perfis) foi observada entre as cepas. Conclusão: Embora não tenha sido observada relação clonal entre os isolados, este estudo revelou dados alarmantes quanto à resistência microbiana em monitoramento preventivo, abordagem ainda pouco adotada no Brasil. Nossos dados permitem concluir que a inclusão de culturas de vigilância nas unidades de saúde é uma estratégia recomendada, visando principalmente à prevenção da disseminação dos genes de resistência no ambiente hospitalar e, consequentemente, redução da morbimortalidade.