RESUMEN
OBJECTIVES: Clostridium difficile is a major global human pathogen divided into five clades, of which clade 3 is the least characterized and consists predominantly of PCR ribotype (RT) 023 strains. Our aim was to analyse and characterize this clade. METHODS: In this cohort study the clinical presentation of C. difficile RT023 infections was analysed in comparison with known 'hypervirulent' and non-hypervirulent strains, using data from the Netherlands national C. difficile surveillance programme. European RT023 strains of diverse origin were collected and whole-genome sequenced to determine the genetic similarity between isolates. Distinctive features were investigated and characterized. RESULTS: Clinical presentation of C. difficile RT023 infections show severe infections akin to those seen with 'hypervirulent' strains from clades 2 (RT027) and 5 (RT078) (35%, 29% and 27% severe CDI, respectively), particularly with significantly more bloody diarrhoea than RT078 and non-hypervirulent strains (RT023 8%, other RTs 4%, p 0.036). The full genome sequence of strain CD305 is presented as a robust reference. Phylogenetic comparison of CD305 and a further 79 previously uncharacterized European RT023 strains of diverse origin revealed minor genetic divergence with >99.8% pairwise identity between strains. Analyses revealed distinctive features among clade 3 strains, including conserved pathogenicity locus, binary toxin and phage insertion toxin genotypes, glycosylation of S-layer proteins, presence of the RT078 four-gene trehalose cluster and an esculinase-negative genotype. CONCLUSIONS: Given their recent emergence, virulence and genomic characteristics, the surveillance of clade 3 strains should be more highly prioritized.
Asunto(s)
Clostridioides difficile/clasificación , Clostridioides difficile/patogenicidad , Infecciones por Clostridium/microbiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Técnicas de Tipificación Bacteriana , Niño , Preescolar , Infecciones por Clostridium/epidemiología , Estudios de Cohortes , Diarrea/microbiología , Femenino , Secuenciación de Nucleótidos de Alto Rendimiento , Hospitales/estadística & datos numéricos , Humanos , Lactante , Masculino , Persona de Mediana Edad , Tipificación de Secuencias Multilocus , Países Bajos/epidemiología , Filogenia , Ribotipificación , Vigilancia de Guardia , Adulto JovenRESUMEN
The diarrheal pathogen Clostridium difficile consists of at least six distinct evolutionary lineages. The RT017 lineage is anomalous, as strains only express toxin B, compared to strains from other lineages that produce toxins A and B and, occasionally, binary toxin. Historically, RT017 initially was reported in Asia but now has been reported worldwide. We used whole-genome sequencing and phylogenetic analysis to investigate the patterns of global spread and population structure of 277 RT017 isolates from animal and human origins from six continents, isolated between 1990 and 2013. We reveal two distinct evenly split sublineages (SL1 and SL2) of C. difficile RT017 that contain multiple independent clonal expansions. All 24 animal isolates were contained within SL1 along with human isolates, suggesting potential transmission between animals and humans. Genetic analyses revealed an overrepresentation of antibiotic resistance genes. Phylogeographic analyses show a North American origin for RT017, as has been found for the recently emerged epidemic RT027 lineage. Despite having only one toxin, RT017 strains have evolved in parallel from at least two independent sources and can readily transmit between continents.
Asunto(s)
Clostridioides difficile/clasificación , Clostridioides difficile/genética , Infecciones por Clostridium/microbiología , Infecciones por Clostridium/veterinaria , Variación Genética , Filogenia , Ribotipificación , Animales , Clostridioides difficile/aislamiento & purificación , Infecciones por Clostridium/epidemiología , Genoma Bacteriano , Salud Global , Humanos , Epidemiología Molecular , Reacción en Cadena de la Polimerasa , Análisis de Secuencia de ADNRESUMEN
Clostridium difficile remains the leading cause of nosocomial diarrhea worldwide, which is largely considered to be due to the production of two potent toxins: TcdA and TcdB. However, PCR ribotype (RT) 017, one of five clonal lineages of human virulent C. difficile, lacks TcdA expression but causes widespread disease. Whole-genome sequencing was applied to 35 isolates from hospitalized patients with C. difficile infection (CDI) and two environmental ward isolates in London, England. The phylogenetic analysis of single nucleotide polymorphisms (SNPs) revealed a clonal cluster of temporally variable isolates from a single hospital ward at University Hospital Lewisham (UHL) that were distinct from other London hospital isolates. De novo assembled genomes revealed a 49-kbp putative conjugative transposon exclusive to this hospital clonal cluster which would not be revealed by current typing methodologies. This study identified three sublineages of C. difficile RT017 that are circulating in London. Similar to the notorious RT027 lineage, which has caused global outbreaks of CDI since 2001, the lineage of toxin-defective RT017 strains appears to be continually evolving. By utilization of WGS technologies to identify SNPs and the evolution of clonal strains, the transmission of outbreaks caused by near-identical isolates can be retraced and identified.
Asunto(s)
Clostridioides difficile/clasificación , Infecciones por Clostridium/epidemiología , Infección Hospitalaria/epidemiología , Diarrea/epidemiología , Brotes de Enfermedades , Enterotoxinas/deficiencia , Ribotipificación , Toxinas Bacterianas , Clostridioides difficile/genética , Clostridioides difficile/aislamiento & purificación , Infecciones por Clostridium/microbiología , Análisis por Conglomerados , Infección Hospitalaria/microbiología , Diarrea/microbiología , Genoma Bacteriano , Humanos , Londres/epidemiología , Epidemiología Molecular , Filogenia , Reacción en Cadena de la Polimerasa , Polimorfismo de Nucleótido Simple , Análisis de Secuencia de ADNRESUMEN
Clostridium difficile is a Gram-positive, spore-forming, human and animal pathogen that is the major cause of antibiotic-associated diarrhoea worldwide. The past decade has seen the rapid emergence of the hypervirulent PCR ribotype (RT) 027 complex, which has been associated with increases in the incidence and severity of disease and mortality. In this review, we describe the potential virulence factors that have been reported in strains from the RT 027 complex. We review the emergence, population structure, dissemination and evolution of this lineage.