Resistant S. sonnei found spreading among people experiencing homelessness
Key takeaways:
- S. sonnei infections increased to 56.5 per year following the start of the COVID-19 pandemic.
- The population experiencing infections shifted from men who have sex with men to people experiencing homelessness.
Researchers found a large increase in resistant Shigella sonnei infections during the COVID-19 pandemic, noting that it spread primarily among people experiencing homelessness, according to a study.
“Starting in 2021, we observed an increase in infections and hospitalizations due to multidrug-resistant Shigella sonnei among people experiencing homelessness in downtown Vancouver,” Aleksandra Stefanovic, MD, clinical professor in the department of pathology and laboratory medicine at the University of British Columbia, told Healio.
This prompted Stefanovic and colleagues to assess the wider epidemiology and genomics of S. sonnei infections.
To do so, the researchers conducted a retrospective review of 163 patients with S. sonnei infections between 2015 and 2022. According to the study, they divided the reported cases into two time periods — the historical period running from 2015 to 2020, and the recent period running from 2021 to 2022.
Overall, the study showed that S. sonnei infections rose from 8.3 cases per year during the historical period to 56.5 cases per year during the recent period. The authors wrote that no cases of S. sonnei were detected in 2020, which they attributed to public health measures put in place during the COVID-19 pandemic.
As these measures began lifting, however, there was an increase in the number of multidrug-resistant Shigella infections, with a significant increase taking place in 2022 (17 cases in 2021 to 96 in 2022). They noted that a dominant strain of multidrug-resistant S. sonnei emerged with resistance to all first- and second-line agents yet with susceptibility to ceftriaxone. Additional data showed that there were more cases of severe shigellosis in the recent period vs. the historical period (61% vs. 14%; P < .001).
Researchers also observed an “epidemiological shift” in affected populations across the two study periods. Specifically, they found that affected populations shifted from being largely men who have sex with men who accounted for 98% of cases to being predominantly people experiencing homelessness who accounted for 77% of cases.
Based on the findings of the investigation, Stefanovic reiterated that Shigella spreads among high-risk populations, “raising concerns for other urban centers with overlapping at-risk communities.”
Because of this, she said, individuals experiencing homelessness face heightened risks of infection due to environmental contamination, increased exposure and limited access to sanitation and hygiene facilities.
“The underlying vulnerabilities of the underhoused individuals can lead to an increase in disease severity. Increased awareness, effective detection strategies and targeted prevention measures are essential to mitigate the spread of these infections,” she said. “We emphasize the urgent need for the accelerated development of vaccines and new antibiotics to combat the rising infections due to multidrug-resistant Shigella strains.”
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Stefanovic A, et al. Clin Infect Dis. 2024;doi:10.1093/cid/ciae575.