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Updated: Jan 14, 2026
Author Spotlight: Advancements in Understanding and Combatting Shigella Infections
Published on: February 9, 2024
Genomic and epidemiological characteristics of Shigella boydii in Australia, 1991-2022
Aaliya F Ibrahim1,2, Danielle J Ingle3,4, Jessica R Webb3,4,5
1National Centre for Epidemiology and Population Health, Australian National University, Canberra, Australia.
Abstract:
Shigellosis is a leading cause of diarrheal mortality worldwide. Shigella boydii is one of four Shigella species that contributes to this burden, however studies on S. boydii are limited. Here we combined epidemiological and genomic data to better understand S. boydii circulating both in Australia and globally. Between 1991 and 2019, there were 294 cases of S. boydii infections notified to the National Notifiable Diseases Surveillance System by Australian states and territories, with an increasing trend in notifications observed from 2013. Of cases whose place of acquisition was known, 54% (111/206) were acquired overseas, mainly from South-East Asia (57%; 63/111). Our genomic analysis included 250 S. boydii isolates: 44 from Victoria, Australia spanning 22 years (2001-2022) and 206 international isolates spanning 91 years (1930-2020). Phylogenomic analyses identified five major S. boydii phylogenetic lineages circulating globally. The Australian isolates were distributed across all five lineages, but the highest proportion was in Lineage 3. Antimicrobial resistance was common in both international and Australian isolates with > 60% of isolates classified as multi-drug-resistant. Resistance to the main clinically relevant antimicrobials was rare in S. boydii. Ciprofloxacin resistance was detected in seven S. boydii, however reduced susceptibility to ciprofloxacin was detected in 56 isolates and found in both Australian and international data. Importantly, resistance mechanisms to third-generation cephalosporins and macrolides were also detected. This study is the largest genomic analysis of S. boydii to date, providing insights into the population structure, epidemiology and emerging AMR threats in this neglected Shigella species.
Insights
This study reveals increasing Shigella boydii infections in Australia, often acquired overseas. Genomic analysis identified five global lineages and common antimicrobial resistance, highlighting emerging threats in this neglected pathogen.
Area of Science:
- Microbiology and Infectious Diseases
- Genomics and Epidemiology
- Antimicrobial Resistance Surveillance
Background:
- Shigellosis, a severe diarrheal disease, causes significant global mortality.
- Shigella boydii is a key contributor, yet remains understudied compared to other Shigella species.
- Understanding S. boydii epidemiology and genetic diversity is crucial for public health.
Purpose of the Study:
- To investigate the population structure and epidemiology of Shigella boydii in Australia and globally.
- To characterize antimicrobial resistance patterns in S. boydii isolates.
- To identify emerging threats associated with S. boydii infections.
Main Methods:
- Combined epidemiological data from Australia's National Notifiable Diseases Surveillance System (1991-2019).
- Conducted phylogenomic analysis on 250 S. boydii isolates (44 Australian, 206 international) spanning up to 91 years.
- Assessed antimicrobial resistance profiles, including multi-drug resistance and specific drug resistance mechanisms.
Main Results:
- Observed an increasing trend of S. boydii notifications in Australia from 2013, with over half of cases acquired overseas, primarily from Southeast Asia.
- Identified five distinct global phylogenetic lineages of S. boydii, with Australian isolates distributed across all lineages, predominantly in Lineage 3.
- Found high rates of multi-drug resistance (>60%) in both Australian and international isolates, with emerging resistance to third-generation cephalosporins and macrolides detected.
Conclusions:
- This comprehensive genomic study provides the largest analysis of S. boydii to date.
- Findings illuminate the global population structure and epidemiological dynamics of S. boydii.
- Highlights the urgent need for enhanced surveillance of antimicrobial resistance in this neglected pathogen.
