What's Happening?
A novel strain of extensively drug-resistant (XDR) Shigella sonnei has been identified in Los Angeles, according to a case report published in Antimicrobial Stewardship & Healthcare Epidemiology. The strain was
isolated from two patients with no known epidemiological connection, a year apart. The patients included a 34-year-old man with advanced HIV and a 33-year-old immunocompromised woman with high-grade B-cell lymphoma. Both isolates were resistant to several oral antibiotics typically used to treat shigellosis, a highly infectious gastrointestinal condition. Molecular analysis revealed the presence of the bla DHA-1 gene, conferring resistance to beta-lactam antibiotics, and the bla CTX-M-15 gene, which has been associated with XDR strains in men who have sex with men (MSM). This discovery is significant as it suggests the emergence of a new strain spreading beyond high-risk populations.
Why It's Important?
The identification of this novel XDR Shigella strain is concerning for public health due to its resistance to multiple antibiotics, which complicates treatment options. The Centers for Disease Control and Prevention (CDC) has previously warned about the rising cases of XDR Shigella in the U.S., with the percentage of resistant isolates increasing from 0% in 2015 to 5% in 2022. The broader spread of this strain could lead to more treatment failures, as it is resistant to all oral drugs, necessitating the use of last-resort intravenous treatments like carbapenem antibiotics. This situation underscores the need for vigilant monitoring and genomic surveillance to prevent widespread transmission and manage potential outbreaks effectively.
What's Next?
The report's authors emphasize the importance of continuous genomic surveillance to track the spread of this novel XDR Shigella strain. Public health officials may need to implement targeted interventions to control its transmission, especially in vulnerable populations. Healthcare providers should be aware of the potential for treatment failures and consider alternative therapeutic strategies. The situation may prompt further research into developing new antibiotics or treatment protocols to address the growing challenge of antibiotic resistance.
