(CBS Local)– A nationwide outbreak stemming from pet adoptions has caused more than 100 people to get sick – and it all has to do with a common bacteria.

Puppies are what the Centers for Disease Control and Prevention said has led to the illnesses in at least 18 states, as far west as Utah.

The cause is campylobacter bacteria — which can trigger diarrhea, stomach pains and fever — and it’s often resistant to antibiotics.

A CDC investigation found that puppies from six pet store chains from January 2017 through February 2018 caused the outbreak.

No deaths have been reported, but at least 26 people have been hospitalized.

Samples taken from each patient showed the bacteria was resistant to all antibiotics used to treat it.

According to the CDC, “dog-associated Campylobacter outbreaks have been reported previously, but those outbreaks involved fewer illnesses, and the isolates were not multidrug-resistant.”

Most people can usually recover from campylobacter bacteria infection in about five days without treatment.

Ninety-nine percent of the patients observed by the CDC said they had direct contact with a dog, and 95 percent said what they touched was a pet store puppy — most of which had been treated with antibiotics themselves.

Despite all of this, the CDC said to just use common sense when around new animals. Wash or sanitize your hands before and after handling them.