Two dogs treated at a veterinary hospital in New Jersey last year have tested positive for a rare, drug-resistant strain of bacteria linked to a fatal outbreak blamed on now-recalled eye drops that had been used in humans, a CDC investigator said Friday.
The animals were infected by a bacteria known as carbapenemase-producing carbapenem-resistant Pseudomonas aeruginosa, found in swabs of the lung and ear of two dogs from different owners at the hospital.
Testing of the bacteria from the dogs found it to be "highly genetically related" to the germs behind an outbreak last year that ultimately sickened 81 human patients across 18 states. By the end of that outbreak, 14 patients lost their vision and four died.
Germs that produce carbapenemase are especially worrying to health officials in part because they can break down carbapenem antibiotics, a class of drugs typically reserved for infections resistant to other treatments, and can easily spread their resistance genes to other pathogens.
"So now that this bacteria has been introduced into the U.S. from the artificial tears, this resistance could spread," the CDC's Emma Price said Friday, presenting her team's findings at a conference of the agency's Epidemic Intelligence Service.
The annual conference of the CDC is described as a gathering of the agency's emerging "disease detectives," where they share updates on their various investigations and studies.
According to Price, one of the dogs was swabbed during a visit to the hospital to help diagnose a chronic cough, while veterinarians were trying to identify the cause of a persistent ear infection in the other dog.
Swabs from the dogs were sent to an academic veterinary laboratory in Pennsylvania, which detected unusual signs of resistance in the germs. The genetic sequence of the strain was then uploaded to a national database, triggering an investigation by the CDC and state health authorities.
"Thanks to a grant and the presence of a veterinary microbiologist at the laboratory, thorough analysis was conducted and the results were uploaded. This is how we were alerted, as the strain matched the outbreak strain," Price explained.
At the same time, the outbreak of eye drops in humans led to a crackdown by the Food and Drug Administration throughout the industry. This resulted in millions more bottles of over-the-counter brands being removed from shelves and banned from importation.
The initial outbreak was attributed to contaminated eye drops produced at a factory in India where inspectors from the Food and Drug Administration ultimately discovered unclean equipment and a long list of shortcuts in hygiene procedures. Other factories have also revealed concerning issues, ranging from barefoot workers to falsified records.
The FDA this year issued a warning.
"The adverse event was in a cat that developed an eye infection after being treated with the drops. However, testing was not able to conclusively prove that the eye drops caused the infection," an FDA spokesperson told CBS News in March, after the warning.
Interviews with the two pet owners did not provide any obvious explanations for how the drug-resistant germs entered their dogs. Neither pet had traveled internationally or visited human hospitals.
"Neither dog owner recalled using the eye drops, although we do acknowledge the difficulty of recalling over the past year," said Price.
Both pets eventually recovered and are now in good health, according to Price. However, their findings raised concerns among investigators, who identified gaps in the animal hospital's infection prevention protocols. These gaps could have facilitated the spread of germs from staff or other pets.
Staff at the hospital had "limited" options for hand hygiene, not meeting the recommendations to provide hand sanitizer in every treatment area.
In a recent investigation, it was found that there was a lack of use of personal protective equipment, particularly gloves, in a veterinary setting. According to Price, shared equipment among staff showed visible soiling and dust accumulation, and supposedly clean supplies were stored in areas prone to contamination.
Price emphasized that these findings are not unique to this particular hospital but reflect a broader issue of inadequate emphasis on infection prevention and control in veterinary settings.
Furthermore, one of the dogs in question lives with three other pets at home, raising concerns about the potential long-term colonization of drug-resistant bacteria in the dog and the risk of transmission to other animals. The CDC notes that human patients can be colonized by infections such as Pseudomonas aeruginosa for extended periods.
Although the owners of the pets were not immunocompromised, Price advised them to be vigilant about potential transmission and to inform their healthcare providers. She also recommended keeping the dogs separated from other animals in the future, acknowledging the challenges associated with this precaution.
