Establishing whole genome sequencing at the core of epidemiological surveillance
Over the last two decades, genome sequencing has become an important tool for understanding and tracking the spread of pathogens. Genomic epidemiology is now a preferred method of surveillance and recent years have seen pathogen sequencing at an unprecedented scale, pushing the underlying technologies to the limit. This has brought major innovations and opportunities to public attention, as well as identifying new research areas. However, major challenges remain in public health settings. These include: incorporating new sequencing technologies and data types for real-time surveillance; developing platforms and nomenclatures for genome-based typing and epidemiology; understanding pathogen evolution and the emergence of virulence and antimicrobial resistance; contextualizing knowledge of clinical microbiology with One Health ecological genomics. In this collection, we bring together recent studies that are establishing pathogen genomics as a major part of contemporary disease control efforts.
Collection Contents
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Genomic analysis of the initial dissemination of carbapenem-resistant Klebsiella pneumoniae clones in a tertiary hospital
More LessCarbapenem-resistant Klebsiella pneumoniae is a major cause of hospital-acquired infections and the fastest-growing pathogen in Europe. Carbapenem resistance was detected at the Consorcio Hospital General Universitario de Valencia (CHGUV) in early 2015, and there has been a significant increase in carbapenem-resistant isolates since then. In this study, we collected carbapenem-resistant isolates from this hospital during the period of increase (from 2015 to 2019) and studied how K. pneumoniae carbapenem-resistant isolates emerged and spread in the hospital. A total of 225 isolates were subjected to whole-genome sequencing with Illumina NextSeq. We characterized the isolates by identifying lineages and antimicrobial resistance genes and plasmids, especially those related to reduced carbapenem susceptibility. Our findings show that the initial carbapenem resistance emergence and dissemination at the CHGUV occurred during a short period of 1 year. Furthermore, it was complex, involving six different lineages of types ST307, ST11, ST101 and ST437, different resistance-determinant factors, including OXA-48, NDM-1, NDM-23 and DHA-1, and different plasmids.
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Genomic surveillance, characterization and intervention of a polymicrobial multidrug-resistant outbreak in critical care
More LessBackground. Infections caused by carbapenem-resistant Acinetobacter baumannii (CR-Ab) have become increasingly prevalent in clinical settings and often result in significant morbidity and mortality due to their multidrug resistance (MDR). Here we present an integrated whole-genome sequencing (WGS) response to a persistent CR-Ab outbreak in a Brisbane hospital between 2016–2018.
Methods. A. baumannii, Klebsiella pneumoniae, Serratia marcescens and Pseudomonas aeruginosa isolates were sequenced using the Illumina platform primarily to establish isolate relationships based on core-genome SNPs, MLST and antimicrobial resistance gene profiles. Representative isolates were selected for PacBio sequencing. Environmental metagenomic sequencing with Illumina was used to detect persistence of the outbreak strain in the hospital.
Results. In response to a suspected polymicrobial outbreak between May to August of 2016, 28 CR-Ab (and 21 other MDR Gram-negative bacilli) were collected from Intensive Care Unit and Burns Unit patients and sent for WGS with a 7 day turn-around time in clinical reporting. All CR-Ab were sequence type (ST)1050 (Pasteur ST2) and within 10 SNPs apart, indicative of an ongoing outbreak, and distinct from historical CR-Ab isolates from the same hospital. Possible transmission routes between patients were identified on the basis of CR-Ab and K. pneumoniae SNP profiles. Continued WGS surveillance between 2016 to 2018 enabled suspected outbreak cases to be refuted, but a resurgence of the outbreak CR-Ab mid-2018 in the Burns Unit prompted additional screening. Environmental metagenomic sequencing identified the hospital plumbing as a potential source. Replacement of the plumbing and routine drain maintenance resulted in rapid resolution of the secondary outbreak and significant risk reduction with no discernable transmission in the Burns Unit since.
Conclusion. We implemented a comprehensive WGS and metagenomics investigation that resolved a persistent CR-Ab outbreak in a critical care setting.
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Genomic surveillance of Escherichia coli and Klebsiella spp. in hospital sink drains and patients
More LessBede Constantinides, Kevin K. Chau, T. Phuong Quan, Gillian Rodger, Monique I. Andersson, Katie Jeffery, Sam Lipworth, Hyun S. Gweon, Andy Peniket, Graham Pike, Julian Millo, Mary Byukusenge, Matt Holdaway, Cat Gibbons, Amy J. Mathers, Derrick W. Crook, Timothy E.A. Peto, A. Sarah Walker and Nicole StoesserEscherichia coli and Klebsiella spp. are important human pathogens that cause a wide spectrum of clinical disease. In healthcare settings, sinks and other wastewater sites have been shown to be reservoirs of antimicrobial-resistant E. coli and Klebsiella spp., particularly in the context of outbreaks of resistant strains amongst patients. Without focusing exclusively on resistance markers or a clinical outbreak, we demonstrate that many hospital sink drains are abundantly and persistently colonized with diverse populations of E. coli , Klebsiella pneumoniae and Klebsiella oxytoca , including both antimicrobial-resistant and susceptible strains. Using whole-genome sequencing of 439 isolates, we show that environmental bacterial populations are largely structured by ward and sink, with only a handful of lineages, such as E. coli ST635, being widely distributed, suggesting different prevailing ecologies, which may vary as a result of different inputs and selection pressures. Whole-genome sequencing of 46 contemporaneous patient isolates identified one (2 %; 95 % CI 0.05–11 %) E. coli urine infection-associated isolate with high similarity to a prior sink isolate, suggesting that sinks may contribute to up to 10 % of infections caused by these organisms in patients on the ward over the same timeframe. Using metagenomics from 20 sink-timepoints, we show that sinks also harbour many clinically relevant antimicrobial resistance genes including bla CTX-M, bla SHV and mcr, and may act as niches for the exchange and amplification of these genes. Our study reinforces the potential role of sinks in contributing to Enterobacterales infection and antimicrobial resistance in hospital patients, something that could be amenable to intervention. This article contains data hosted by Microreact.
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Genomic survey of Clostridium difficile reservoirs in the East of England implicates environmental contamination of wastewater treatment plants by clinical lineages
More LessThere is growing evidence that patients with Clostridiumdifficile-associated diarrhoea often acquire their infecting strain before hospital admission. Wastewater is known to be a potential source of surface water that is contaminated with C. difficile spores. Here, we describe a study that used genome sequencing to compare C. difficile isolated from multiple wastewater treatment plants across the East of England and from patients with clinical disease at a major hospital in the same region. We confirmed that C. difficile from 65 patients were highly diverse and that most cases were not linked to other active cases in the hospital. In total, 186 C. difficile isolates were isolated from effluent water obtained from 18 municipal treatment plants at the point of release into the environment. Whole genome comparisons of clinical and environmental isolates demonstrated highly related populations, and confirmed extensive release of toxigenic C. difficile into surface waters. An analysis based on multilocus sequence types (STs) identified 19 distinct STs in the clinical collection and 38 STs in the wastewater collection, with 13 of 44 STs common to both clinical and wastewater collections. Furthermore, we identified five pairs of highly similar isolates (≤2 SNPs different in the core genome) in clinical and wastewater collections. Strategies to control community acquisition should consider the need for bacterial control of treated wastewater.
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