Los Angeles County (LAC) Health authorities issued a national biorisk warning today. The warning comes after identifying a patient infected with the mcr-1 pathogen. The patient apparently contracted the pathogen while travelling internationally.
Mcr-1 is an incredibly dangerous bacterium for several reasons. First, it is 100% drug-resistant. That means that as of today, we have no known drugs to combat the infection. The only defense we have is preventing an outbreak and that means understanding the pathogen.
Bacteria become drug resistant when infections are over-treated with antibiotics. In the case of mcr-1, an older drug suddenly became popular for treating infections. Colistin has been in use since 1959, however, due to the problems it can cause with kidneys, it was often only used as a last resort.
That was what made it so helpful when doctors began coming across more and more resistance to all the other options. So, with no alternatives, they turned to colistin and began using it regularly. You already know how that story ends.
In an added twist, because colistin is old, it is also cheap, making it attractive for large-scale use. Farmers have been using the drug to feed to animals to boost growth and protect them. China has the market cornered on colistin. Of the top ten largest producers of the drug for veterinary use, one is Indian, one is Danish, and eight are Chinese.
Scientists first reported the emergence of the mcr-1 gene in a Pennsylvania female patient with a urinary tract infection in November 2015.
A worldwide biorisk warning was issued at that time. This warning sent scientists all over the world to digging to see if they could find any trace of the bacteria in their own samples. Which brings us back to China.
English and Chinese microbiologists found almost 100 instances of the biorisk gene. With some of the frozen samples going back over five years, Chinese researchers indicated that mcr-1 resistance may be more widely distributed than expected.
Their findings included;
78 of 523 (15%) samples of raw pork and chicken meat.
166 of 804 (21%) pigs in slaughterhouses.
16 of 1,322 (1%) samples from hospital patients with infections.
As you can see by the numbers, China’s wide use in animals has led to a large number of cases turning up in slaughterhouses. From there, it is only a short trip to a person’s dinner plate and the infection being spread.
That is the other reasons mcr-1 is so dangerous, scientists discovered that the bacteria is zoonotic, which means it can be transferred from humans to animals or vice versa.
After it was first determined that seagulls may carry mcr-1, health officials realized that the gene could be subject to airborne transmission; transmission through animal interactions; through handling infected meat; and by drinking animal-contaminated water.
With so many ways for it to be transmitted, it is only a matter of time before it begins turning up in more places.
So far, Los Angeles County is reporting no evidence of spread in the local healthcare community. While that is good news, it could simple mean that others haven’t been found yet. Jerry Brown’s state will need help from the national scientific community to make sure this is accurate
The bulletin from L.A also reveals that since the patient in Pennsylvania, the “mcr-1” gene has been reported in human specimens from five additional states and in animal specimens from two states.
With this new find, hospitals and doctors will be following protocol set forth by the Los Angeles County Department of Public Health (DPH). Due to California’s shaky economic status, it is unknown if they actually have the means of following through with all this.
The guidelines include;
- Infection Prevention: Healthcare providers should follow Standard Precautions for any patient who is suspected to be infected with mcr-1 positive organisms pending mcr-1 confirmation, OR any patient confirmed to be infected with mcr-1 positive organisms.
- Laboratory Testing: Isolates should be tested for the presence of mcr-1. If hospital mcr-1 confirmatory testing cannot be performed, contact LAC DPH Acute Communicable Disease Control (ACDC).
- Reporting: All mcr-1 positive isolates identified in LAC residents and at LAC health care facilities must be reported within one working day (24 hours).
Mcr-1 is different from other drug resistant bacteria we have seen due to its role in agriculture. The problem is two-fold. First, thousands to millions of animals are getting the colistin drug, which exponentially expands the opportunities that favor resistance. And second, projects such as the Chinese one that allowed the new gene to be discovered are rare; so colistin resistance could begin moving, from animals and into people, without being noticed.
It may actually be on the move already. The European Molecular Biology Laboratory received five submissions of bacterial data that appeared to contain the MCR gene. The samples did not come from China but from Malaysia.
Unfortunately it may be days, weeks, or even months before we hear more. If this truly is an isolated case, hopefully it will be even longer. If more patients turn up positive then we may start seeing more widespread warnings or precautions.