The story behind the paper

We recently published a paper on genomic surveillance of a diarrhoeal pathogen Shigella sonnei across Latin America which represented the culmination of over five years of collaboration, as well as training and development in the region

Graphical abstract

In collaboration with the Wellcome Trust Sanger Institute, the Pan American Health Organisation and PulseNet Latin America and Caribbean (PNLAC), we whole genome sequenced over 400 Shigella sonnei collected from nine countries over two decades. Shigella are the most important bacterial cause of moderate-to-severe childhood diarrhoeal disease in low to middle income nations, and countries in Latin America still experience endemic disease and explosive outbreaks. By sharing information on common pathogen subtypes through public health networks, like PNLAC, pathogens can be traced epidemiologically to facilitate early identification and intervention in disease outbreaks. Whole genome sequencing is transforming surveillance of bacterial pathogens, as it provides the highest resolution of pathogens subtypes and can also be used to explore other genetic factors of interest, like antimicrobial resistance. However, its cost precludes routine use in some areas, which are unfortunately some of those regions where the most Shigella disease is seen.

In this study, we sequenced approximately 50 isolates from nine countries in Latin America and use whole genome phylogenetics to reveal those sublineages that were responsible for most of the disease in the region. We identified a novel global lineage of Shigella sonnei, and by correlating the geography of where isolates came from to their evolutionary relationships, we could see international transmission of some sublineages and what the distribution of different sublineages was across the continent. Visit the microreact page to play with the data yourself.

We were also able to identify key determinants of antimicrobial resistance in the pathogens and how they were distributed among the different sublineages, providing key information for managing this important disease in the region.

In addition to constructing this invaluable regional framework for ongoing surveillance, this project helped build capacity for whole genome sequencing surveillance in the region. Over the course of the collaboration, the World Health Organisation sponsored the establishment of whole genome sequencing facility at the reference laboratory for PNLAC, ANLIS in Buenos Aires, Argentina (see photo). In the paper, we show how locally-generated sequencing data from this facility can be integrated into the regional surveillance framework to determine whether outbreaks were due to locally-circulating lineages or resulted from the importation of new sublineages.

In addition to laboratory capacity building, the collaboration involved training an ANLIS researcher (Josefina Campos – see photo – who now runs the genomics facility there) in bioinformatics, and conducting training courses (in conjunction with Wellcome Trust Advanced Courses) for medical, veterinary and public health professionals in the region, including courses in Argentina, Uruguay and Costa Rica (see picture).

There are 29 authors on our paper and every one of them worked hard on, and cared deeply about, the outcome of the study as well as the training programs and capacity building surrounding it. Every paper has a story behind it, and this one, like so many others, is so much more than it appears.

Photo: Top ANLIS in Buenos Aires, Argentina. Bottom (from right to left) ANLIS collaborator Josefina Campos and co-corresponding author Nicholas Thomson (WTSI) outside the Malbran (ANLIS) Institute; Genomics for Epidemiology and Surveillance of Bacterial Pathogens course instructors and participants held in February 2015 in San Jose, Costa Rica; co-corresponding author Kate Baker with bust of Carlos Gregorio Malbran, the ANLIS institute’s namesake.

Lay summary on Latin America.png

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