In nearly all cases involving mcr-1 worldwide, the gene is carried on a plasmid, a mobile piece of DNA that easily can transfer the gene to other bacteria.
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In this case, although the girl’s bacterial infection was resistant to colistin, it was not resistant to all antibiotics, according to the CDC report.
The Connecticut case “points to a food-borne acquisition as the most probable cause”, said Moraya Walters, a CDC epidemiologist. When the girl got better, the bacteria that contained the gene disappeared within a week of her recovery, Walters said. She developed fever and bloody diarrhea on June 12, two days before returning to the United States. The fear is that mcr-1, combined with other forms of antibiotic resistance, will give rise to bacteria that can not be successfully treated with antibiotics. So far, it hasn’t gone from person to person, she added. An investigation by state and federal health officials found that the strain of E. coli is not what made her sick.
Although the strain discovered in the child was resistant to colistin, a last resort antibiotic for drug-resistant bacteria, it was not resistant to all antibiotics.
Although the mcr-1 gene was found, it wasn’t producing toxins.
Antibiotic resistance has become a global concern. The child is a 2-year-old girl, and the detection was an incidental finding, the Washington Post reported, citing CDC officials.
“The concern is that it could move into bacteria that are already highly resistant and could render them resistant to all antibiotics, but we have not seen this in the USA”, she said. It has also been found in hospitals, so it might be transmitted in that setting.
Two people in the U.S. who were infected by a superbug this year have recovered, and no new case of the infection has been reported so far. The woman, who had been hospitalized multiple times in the time leading up to the discovery, was being evaluated for a possible urinary tract infection.
The gene spreads among the human body by being carried on a plasmid, which is a DNA piece capable of transfering genes to bacteria.
Investigators said they don’t know how she got the superbug.
If this were to happen, researchers have stated the gene would become an invincible superbug unable to be treated with any modern antibiotic. This was the first reported case of the gene in U.S soil, which made experts fear a future outbreak. She had no worldwide travel for one year, no exposure to livestock and a “limited role in meal preparation with store-bought groceries”, the CDC found. They are from the state’s health department and the CDC.
The E coli bacteria containing the mcr-1 gene have been found in farm animals, but it isn’t clear how people get the bacteria, Walters said. In addition, no colistin-resistant organisms were found among more than 50 samples of a serious drug-resistant bacteria collected from the four medical facilities to which she was admitted during 2016.
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After the case was reported, experts investigated the patient’s environment, food ingestions and tested her whole environment but couldn’t found the source of infection. Taken together, the findings suggest that the transmission risk-even among high-risk contacts-from a colonized patient may be relatively low, the group wrote.
