Clusters of cases of the fungal infection usually involve a hospital network, as opposed to a single facility, as patients transfer between long-term care facilities and acute care hospitals, according to an expert with Emory University School of Medicine.

Shigella causes shigellosis, an inflammatory diarrhea. The extensively drug-resistant strain is relatively uncommon overall, but it's being seen in more cases among adults.

EzriCare artificial tears are suspected to be the cause of an outbreak of the VIM-GES-CRPA strain of Pseudomonas aeruginosa, which the CDC said is the first outbreak of its kind in the U.S.