The kitten's owner and the director of the animal rescue group that supplied the kitten are being treated for the disease as a precaution, though it is not yet known if either person was infected.
The Prince George County health department is asking people to contact the agency if they came into contact with kittens at the Greenbelt store's adoption center.
The six kittens were in the PetSmart store May 14 to 19, said John Marsiglia, manager of the Greenbelt location. The suspension of pet adoptions involves 22 stores in Maryland and Virginia.
The store learned of the infection last week after the owner returned the kitten because it was lurching and unsteady, said Cindy Sharpley, director of Last Chance Animal Rescue. The kitten bit Sharpley on her hand when she tried to handle it.
The infected kitten and its five littermates were euthanized, she said. Even though pets are vaccinated before they are adopted, rabies has an incubation period in which it isn't detectable.
"It is a tragic incident, and there was nothing that anyone could have done to prevent this from happening," she said.
PetSmart has arranged more than 3 million adoptions in its 17-year history, and has only had one other rabies case, said Paul Amirault, district manager for PetSmart.