MEXICO CITY — The U.S. Centers for Disease Control and Prevention issued a report Thursday about three cases of infections apparently linked to stem-cell treatments American patients received in Mexico.

The CDC issued the report Thursday on infections of Non-Tuberculous Mycobacteria (NTM), which it described as “difficult-to-treat” and “intrinsically drug-resistant” and “rapidly growing.”

All three patients detected at two Colorado hospitals remain in treatment. The infections were apparently acquired during stem-cell injections carried out at two different clinics in the Mexican border state of Baja California located 167 miles apart.

In the past, Americans and Mexicans have been infected apparently because some doctors in Mexico were taking multiple doses of anesthetics from a single vial due to shortages or other problems, though it was not clear if that was a possible cause in the most recent outbreak reported Thursday.

The first case was reported in late 2022, in a woman who had embryonic stem-cell treatment in October 2022 for multiple sclerosis.

In spring 2023, two male patients in Colorado were found to have infections in their joints after receiving stem-cell treatments in Baja California for forms of arthritis.

The CDC report said “vigilance for similar cases and guidance for persons considering medical tourism are advised.”

In the past, local problems with the availability of morphine and fentanyl led some anesthesiologists in Mexico to acquire their own supplies, carry the vials around with them, and administer multiple doses from a single vial to conserve their supply.

In 2022, anesthetics contaminated by those practices caused a meningitis outbreak in the northern state of Durango that killed about three dozen people, many of whom were pregnant women given epidurals. Several Americans died because of a similar outbreak after having surgery at clinics in the Mexican border city of Matamoros in 2023.