NEWPORT, Ore. The $15 billion ornamental fish industry faces a global problem with antibiotic resistance, a new study concludes, raising concern that treatments for fish diseases may not work when needed and creating yet another mechanism for exposing humans to antibiotic-resistant bacteria.
The risk to humans is probably minor unless they frequently work with fish or have compromised immune systems, researchers said, although transmission of disease from tropical fish has been shown to occur. More serious is the risk to this industry, which has grown significantly in recent years, and is now a $900 million annual business in the United States.
There are few regulations in the U.S. or elsewhere about treating ornamental fish with antibiotics, experts say. Antibiotics are used routinely, such as when fish are facing stress due to transport, whether or not they have shown any sign of disease.
"We expected to find some antibiotic resistance, but it was surprising to find such high levels, including resistance in some cases where the antibiotic is rarely used," said Tim Miller-Morgan, a veterinary aquatics specialist with Oregon State University. "We appear to already have set ourselves up for some pretty serious problems within the industry."
In the new study, 32 freshwater fish of various species were tested for resistance to nine different antibiotics, and some resistance was found to every antibiotic. The highest level of resistance, 77 percent, was found with the common antibiotic tetracycline. The fish were tested in Portland, Ore., after being transported from Colombia, Singapore and Florida.
Findings of the study were reported in the Journal of Fish Diseases.
The bacterial infections found in the fish included Aeromonas, Pseudomonas, Staphylococcus and others, several of which can infect both fish and humans.
"The range of resistance is often quite disturbing," the scientists wrote in t
|Contact: Tim Miller-Morgan|
Oregon State University