130. increase in Multidrug Resistance (2011–2018) and the Emergence of Extensive Drug Resistance (2020) in shigella Sonnei in the United States

The increasing antimicrobial resistance of Shigella species among Iranian pediatrics: a systematic review and meta-analysis

BACKGROUND

Shigellosis remains one of the global causes of morbidity and mortality. However, the global emergence of antibiotic resistance has become the leading cause of treatment failure in shigellosis. This review aimed to provide an updated picture of the antimicrobial resistance rates in Shigella species in Iranian pediatrics.

METHODS

A comprehensive systematic search was performed on PubMed, Scopus, Embase, and Web of Science until 28 July 2021. The meta-analysis was performed by computing the pooled using a random-effects model with Stata/SE software, v.17.1. The discrepancy within articles was surveyed by the forest plot in addition to the I2 statistic. All statistical interpretations were reported on a 95% confidence interval (CI) basis.

RESULTS

Totally, of 28 eligible studies published between 2008 and 2021. The pooled prevalence rate of multidrug-resistant (MDR) was 63% (95% CI 50-76). Regarding suggested antimicrobial agents for Shigella species, the prevalence of resistance for ciprofloxacin, azithromycin, and ceftriaxone as first- and second-line treatments for shigellosis were 3%, 30%, and 28%, respectively. In contrast, resistance to cefotaxime, cefixime, and ceftazidime was 39%, 35%, and 20%. Importantly, subgroup analyses indicated that an increase in resistance rates during the periods (2008-2014, 2015-2021) was recognized for ciprofloxacin (0 % to 6%) and ceftriaxone (6% to 42%).

CONCLUSION

Our findings revealed that ciprofloxacin is an effective drug for shigellosis in Iranian children. The substantially high prevalence estimation proposes that the first- and second-line treatments for shigellosis are the major threat to public health and active antibiotic treatment policies are essential.

Clonal serotype 1c multidrug-resistant Shigella flexneri detected in multiple institutions by sentinel-site sequencing

Shigella flexneri is a major diarrhoeal pathogen, and the emergence of multidrug-resistant S. flexneri is of public health concern. We report the detection of a clonal cluster of multidrug-resistant serotype 1c (7a) S. flexneri in Singapore in April 2022. Long-read whole-genome sequence analysis found five S. flexneri isolates to be clonal and harboring the extended-spectrum β-lactamases bla_CTX−M−15 and bla_TEM−1. The isolates were phenotypically resistant to ceftriaxone and had intermediate susceptibility to ciprofloxacin. The S. flexneri clonal cluster was first detected in a tertiary hospital diagnostic laboratory (sentinel-site), to which the S. flexneri isolates were sent from other hospitals for routine serogrouping. Long-read whole-genome sequence analysis was performed in the sentinel-site near real-time in view of the unusually high number of S. flexneri isolates received within a short time frame. This study demonstrates that near real-time sentinel-site sequence-based surveillance of convenience samples can detect possible clonal outbreak clusters and may provide alerts useful for public health mitigations at the earliest possible opportunity.

Clinical and Genomic Investigation of an International Ceftriaxone- and Azithromycin-Resistant Shigella sonnei Cluster among Men Who Have Sex with Men, Montréal, Canada 2017-2019

Multidrug-resistant (MDR) Shigella sonnei have become prevalent among men who have sex with men and have become a global public health concern. From June 2017 to April 2019, 32 men were infected with MDR S. sonnei acquired locally, in Montréal, which was suggestive of an outbreak. Antimicrobial susceptibility testing, whole-genome sequencing (WGS), phylogenetic analysis, antimicrobial resistance and virulence characterization, and association to international clusters were performed. The outbreak strain was ceftriaxone- and azithromycin-resistant due to the acquisition of bla_CTX-M-27, and mphA and ermB genes, respectively, with reduced susceptibility to ciprofloxacin due to a single point mutation (gyrA S83L). One out of 27 patients treated with a fluoroquinolone experienced microbiological failure. Epidemiological evidence first supported by a rare unique MDR Shigella sonnei documented only in men in 2017 followed by similar pulsed-field gel electrophoresis profiles was confirmed by WGS. A core genome high-quality single-nucleotide variant (hqSNV)-based phylogeny found a median of 6 hqSNV differences among isolates. Virulence gene content was investigated, but no Shiga toxins were detected. An international cluster of highly related isolates was identified (PDS000019750.208) and belonged to the 3.7.29.1.4.1 S. sonnei genotype (Global III VN2.KH1.Aus). Genomic analysis revealed that this Montréal cluster was connected to other documented outbreaks in Australia, the United States, and the United Kingdom. This study highlights the urgent need for public health measures to focus on the prevention and the early detection of S. sonnei, since global transmission patterns of MDR strains is concerning and few antimicrobial treatment options are available.

IMPORTANCEShigella sonnei, an important foodborne pathogen, recently became a frequent sexually transmitted agent involved in large and persistent outbreaks globally among men who have sex with men. Most strains also harbor several multidrug-resistant (MDR) determinants of particular concern. This study characterizes an outbreak strain at the source of an important MDR cluster identified in Montréal in 2017. Associations were made to many high-profile international outbreaks, and the causative S. sonnei lineage of these clusters was identified, which was not evident in past reports. The worldwide occurrence of this strain is of concern since treatment with antimicrobials like ceftriaxone and azithromycin may not be effective, and rare microbiological failures have been documented in patients treated with ciprofloxacin. Our investigation highlights the threats of Shigella spp. infection and the necessity for antimicrobial susceptibility monitoring in order to mitigate S. sonnei’s impact on public health and to avoid transmission to other at-risk communities.