Seattle: Genomic methods aid study of 2017-2022 Shigella outbreak


A genomic study of an ongoing multidrug-resistant shigellosis outbreak in Seattle has enabled scientists to recover its origin and spread. Further analysis of the gut pathogen and its modes of transmission helped guide approaches to testing, treatment, and public health responses.


Genomic reconstruction of the 2017-2022 outbreak and review of patient care and public health interventions used reported on January 30. The Lancet Infectious Diseases.

The Seattle researchers note, “The aim of the study is to understand community transmission of Shigella the spread of antimicrobial resistance in our population, and the treatment of these multidrug-resistant infections more effectively.”

Shigella Outbreaks of the disease are more frequent in countries that lack adequate public health and sanitation resources. But the researchers called Shigella An opportunistic pathogen that can also appear in areas of high-income countries when conditions permit.

They explained that it would continue Shigella The outbreak of the disease in urban areas poses a major public health challenge for the population trying to adapt to the harsh living conditions and lack of hygiene facilities.

The lead authors of this paper are Dr Gianola S. Tansarli of the Department of Laboratory Medicine and Pathology, and Dr. Dustin R. Medicine.

Senior author and reporter is Dr. Viric C. Fang, professor of laboratory medicine, pathology, and microbiology at the University of Washington School of Medicine. He directs the Clinical Microbiology Laboratory at Harborview Medical Center and conducts basic science research on how bacteria cause disease. He was assisted by his University of Washington medical colleague Dr. Stephen J. Salibant, MD, a molecular genetic pathologist and expert in next-generation DNA sequencing technologies.

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Shigellosis causes it Shigella Bacteria, which can produce inflammation in the lining of the intestine. Its symptoms include fever, stomach cramps, diarrhea, and in the worst cases, dysentery and dehydration. Some people infected with shigellosis become very ill and require hospitalization. Shigellosis is highly contagious. It is enough for a few bacteria to pass through to cause disease.

From 2017 to 2022, all cases Shigella Identified by the clinical laboratories at Harborview Medical Center and UW Medical Center characterized by species identification, susceptibility testing, and whole-genome sequencing. For the study, the researchers retrospectively examined the demographics and clinical outcomes of affected patients.

Of the 178 cases, 78, or 45.6%, were among men who have sex with men, and 88, or 51.5%, were of people experiencing homelessness. about half Shigella The isolates were resistant to many antibiotics.

The researchers also had data on 143 patients who received antimicrobial therapy. Despite the high presence of drug resistance ShigellaApproximately 70 percent of patients were found to have received appropriate antimicrobial therapy Shigella infection. The researchers added that rapid diagnosis and culture of the bacteria for patients seeking care for acute diarrhoea, along with assessment of risk factors and a detailed local understanding of the affected population, led to higher rates of appropriate treatment. The approach to care has improved over time, as doctors have gained more experience with the disease.

The genomic analysis portion of the study revealed sequenced outbreaks of several distinct strains of two species of C ShigellaAnd S. flexneri And S. Sonney. Various populations are found to be at risk Shigella from different strains with different drug resistance traits. This information has helped clinicians develop effective treatment guidelines.

how did you do this Shigella An outbreak appears in Seattle? The researchers’ genetic findings indicate that it originally came from international travelers from regions where Shigella was common. It then spreads locally and rapidly among vulnerable groups.

The researchers explained that multidrug resistance Shigella It has become a growing global health concern with many outbreaks around the world. Most of these cases affected men who have sex with men. A variety of gut pathogens can be passed between men in this way.

However, in the past few years, outbreaks of shigellosis have also occurred among people experiencing homelessness in West Coast cities of the United States and Canada.

Whole genome sequencing enabled the researchers to identify this novelty S. Sonney And S. flexneri The Strains first appeared in Seattle among MSM. Transmission among the local population of people experiencing vagrancy quickly followed. This is evidenced by the significant increase in shigellosis after 2020 in the Seattle King County area among this population.

The outbreak was worse in the winter, which is a seasonal feature Shigella Which may be caused by overcrowding in shelters and other places during cold weather. Dr. Fang noted that cases of shigellosis have a different cause S. Sonney The strain is now being encountered in Seattle this winter.

The outbreaks in Seattle followed patterns characteristic of those previously reported in other countries.

Several public health measures have been put in place to limit the spread Shigella. The first is to check potential sources of contracting Shigella. Signs have been put up to discourage people from drinking water from the ornate fountains in downtown Seattle. Local homeless service providers received prevention resources and guidance. Outreach teams visited camps and overnight shelters to provide health education and improve the availability of clean water, latrines, hand-washing stations and other sanitation measures.

Many public facilities, such as bathrooms, sinks, and drinking fountains, have closed as part of the response to the COVID-19 pandemic. Public health officials have requested the early reopening of these facilities near campsites and areas where people live on the streets. They also increased environmental cleaning of alleyways in downtown Seattle that were used in place of restrooms.

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