U.S – The U.S. Centers for Disease Control and Prevention (CDC) have employed whole genome sequencing (WGS) to identify a persistent, drug-resistant strain of Escherichia coli O157:H7. and linked it to multiple foodborne illness outbreaks.
The strain, REPEXH01, is classified as “persistent” because it has already been linked to numerous outbreaks and cases of foodborne disease in the United States.
The majority of bacteria recovered from sick people’s samples were resistant to tetracycline, trimethoprim-sulfamethoxazole, streptomycin, chloramphenicol, and sulfisoxazole.
The first E. coli O157:H7 REPEXH01 infection was reported to the CDC’s PulseNet in 2017. Since then, 634 REPEXH01 illnesses have been reported, and 14 foodborne illness outbreak investigations involving the strain have been conducted.
The CDC was able to pinpoint two verified causes and three suspected sources of the outbreaks of foodborne illnesses using WGS.
Epidemiological, traceback, or laboratory findings implicated confirmed sources, which also include romaine lettuce and recreational water.
Only epidemiologic data was used to identify the suspected sources, which in two cases involved ground beef and in a third involved leafy greens.
According to WGS, the bacteria in REPEXH01 are within 21 allele differences of one another, demonstrating the genetic diversity of this strain.
As a result, REPEXH01 has a wider genetic diversity than typical multistate foodborne outbreaks, where bacteria are typically only 10 alleles apart.
WGS also revealed that the strain contains two significant genetic subclusters, each of which has been connected to at least two outbreaks in various geographic and source regions.
Researchers are still looking at potential causes for the variations among genomic subclusters.
To find out if any genetic subclusters are connected to particular foods, animal populations, or geographical areas, more research is required.
Information on E. coli O157:H7 REPEXH01’s antibiotic resistance can be obtained from the National Antimicrobial Resistance Monitoring System (NARMS) surveillance system.
NARMS is a national public health surveillance system that tracks antimicrobial resistance for certain intestinal bacteria from sick people (CDC), retail meats (FDA), and food animals (USDA) in the United States.
The NARMS program helps protect public health by providing information about emerging antimicrobial resistance, how resistance is spread, and how resistant infections differ from susceptible infections.
Increased Shigellosis incidents
The CDC has also issued a health warning on extensively drug-resistant (XDR) Shigella infections.
The National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS) has documented an increase in the incidence of XDR shigellosis, which the CDC has been tracking.
Shigella illnesses caused by XDR strains that were reported to the CDC increased from 0% in 2015 to 5% in 2022, according to the CDC.
Azithromycin, ciprofloxacin, ceftriaxone, trimethoprim-sulfamethoxazole (TMP-SMX), and ampicillin are all examples of typical empiric and substitute antibiotics that the CDC identifies as being ineffective against XDR Shigella bacteria.
The antibiotic therapy of XDR shigellosis is not currently recommended due to a lack of clinical data to support it.
Shigella bacteria are very contagious, and human instances of the disease are frequently brought on by consuming tainted food or drink.
Shigella XDR strains can also transfer genes for antibiotic resistance to other intestinal bacteria.
CDC is reminding healthcare providers that shigellosis is a nationally notifiable disease. Cases of XDR Shigella infection should be reported to local or state health departments.