PHILADELPHIA (CBS) — The Delaware State Health Department says a resident there has the first known U.S. case of NDM-producing carbapenem-resistant Pseudomonas aeruginosa, a drug-resistant bacterial infection first reported in Serbia.

The 81-year-old New Castle county resident, who’s hospitalized and receiving treatment, had underlying medical conditions.

The Pennsylvania Health Department confirms with Eyewitness News there is a second confirmed case in Pennsylvania.

Both individuals had been hospitalized at the same location in Pennsylvania.

The infection is mainly a concern for people who are hospitalized with weakened immune systems.  Pseudomonas bacteria can cause a variety of health care-associated infections, most commonly infections in the lungs and urinary tract and bloodstream.

The CDC along with the state health departments are investigating.