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Background: In 2014, two residents of a long-term care facility (LTCF) developed invasive group A streptococcal (iGAS) infections with identical typing (emm 11), resulting in one death. The second resident recovered but had a subsequent episode of emm 11 iGAS infection 10 months later. This second episode was linked to a third case, within 12 days, leading to a further outbreak investigation.Aim: To combine different techniques to establish whether this was a protracted outbreak, understand transmission pathways and inform appropriate control measures.Methods: Following a routine response to the first cluster, the second investigation included a care record review. This informed network analysis of case interactions with staff and visitors during 10 days prior to infection. These data were combined with post-outbreak whole-genome sequencing (WGS) using isolates from cases, and staff and resident screening (44 GAS isolates: 11 outbreak-related and 33 sporadic isolates).Findings: Two of the three confirmed iGAS cases died (one suffered two episodes). All iGAS cases, and six non-invasive isolates from 2015, were emm 11 (monophylogenetic WGS clade). Network analysis highlighted only indirect contact through staff-visitor interactions between iGAS cases in 2015. This suggested a common source and transmission propagation through carriage and/or environmental contamination over an 11-month period.Conclusions: This outbreak highlighted benefits of staff/resident screening and typing as part of routine response. Network analysis and highly discriminatory WGS clarified the protracted nature of the outbreak, supporting findings of hygiene and infection control issues and adding to our understanding of the epidemiology. [ABSTRACT FROM AUTHOR]

Background: Whole genome sequencing (WGS) of Streptococcus pyogenes linked to invasive disease has been used to identify and investigate outbreaks. The clinical application of WGS in real-time for outbreak control is seldom employed.Aims: A fatal case of bacteraemia at a national orthopaedic hospital prompted an outbreak investigation to identify carriers and halt transmission using real-time WGS.Methods: Retrospective surveillance was conducted to identify patients with Streptococcus pyogenes infections in the last year. Upon contact tracing, four patients and 179 staff were screened for Streptococcus pyogenes carriage. All isolates identified were emm-typed. WGS was performed in real-time on a subset of isolates.Findings: Twelve isolates of Streptococcus pyogenes from the index case, two patients and eight staff were identified. Six isolates were emm 1.0, including the index case and five staff isolates. The remaining isolates belonged to distinct emm types. WGS analysis was undertaken on the six emm 1.0 isolates. Five were indistinguishable by single nucleotide polymorphism (SNP) analysis, with 0 SNP distance, and one had one SNP difference, supporting the hypothesis of recent local transmission. All screen-positive healthcare workers were offered treatment with penicillin or clindamycin. No further cases were identified.Conclusion: The increased molecular discrimination of WGS confirmed the clustering of these cases and the outbreak was contained. This demonstrates the clinical utility of WGS in managing outbreaks of invasive Streptococcus pyogenes in real-time and we recommend its implementation as a routine clinical service. [ABSTRACT FROM AUTHOR]

Background: The clinical manifestations of group A streptococcus (GAS) (Streptococcus pyogenes) are diverse, ranging from asymptomatic colonization to devastating invasive disease. Maternity-related clusters of invasive GAS (iGAS) infection are complex to investigate and control, especially if recurrent.Aim: To investigate three episodes of emm 75 GAS/iGAS infection in maternity patients at one hospital site over a four-year period (two with monophyletic ancestry).Methods: The episodes are described, together with whole-genome sequence (WGS) isolate analyses. Single nucleotide polymorphism differences were compared with contemporaneous emm 75 genomes.Findings: Over the four-year study period, seven mothers had emm 75 GAS/iGAS and one mother had emm 3 iGAS (in year 4) (subsequently discounted as linked). Three (clinical/screening samples) of the seven babies of emm-75-positive mothers and three screened healthcare workers were positive for emm 75 GAS. WGS similarity suggested a shared ancestral lineage and a common source transmission, but directionality of transmission cannot be inferred. However, the findings indicate that persistence of a particular clone in a given setting may be long term.Conclusions: Occupational health procedures were enhanced, staff were screened, and antibiotic therapy was provided to GAS-positive staff and patients. The definitive source of infection could not be identified, although staff-patient transmission was the most likely route. The pattern of clonal GAS transmission over the four-year study period suggests that long-term persistence of GAS may have occurred. [ABSTRACT FROM AUTHOR]

Objectives Legionella pneumophila serogroup 1 (Lp1) sequence type 47 is the leading cause of legionellosis in north-western Europe, but, surprisingly, it is rarely isolated from environmental samples. Comparative genomics was applied to develop a PCR assay and to better understand the evolution of this strain. Methods Comparative analysis of 36 genomes representative of the Lp species was used to identify specific PCR targets, which were then evaluated in silico on 545 sequenced genomes and in vitro on 436 Legionella strains, 106 respiratory samples, and three environmental samples from proven ST47 sources. Phylogenetic analyses were performed to understand the evolution of ST47. Results The gene LPO_1073 was characterized as being 100% conserved in all 129 ST47 genomes analysed. A real-time PCR designed to detect LPO_1073 was positive for all 110 ST47 strains tested and agreed with culture and typing results previously obtained for 106 respiratory samples. The three environmental samples were also positive. Surprisingly, 26 of the 44 ST109 strains tested among 342 non-ST47 strains scored positive for LPO_1073. SNP-based phylogenetic analysis was undertaken to understand this result: the PCR-positive ST109 genomes were almost identical to ST47 genomes, with the exception of a recombined region probably acquired by ST47 from a ST62(-like) strain. Conclusion The genomic analysis allowed the design of a highly specific PCR assay for rapid detection of ST47 strains. Furthermore, it allowed us to uncover the evolution of ST47 strains from ST109 by homologous recombination with ST62. We hypothesize that this recombination generated the leading cause of legionellosis in north-western Europe. [ABSTRACT FROM AUTHOR]