Mycobacterium abscessus is a fast-growing nontuberculous mycobacterium that is naturally resistant to many drugs and hard to treat. Infections outside the lungs have been linked to medical tourism. This CDC report describes three patients infected after stem cell injections in Mexico in 2022.
Three patients
| Patient | Treatment | Where and when | Infection |
|---|---|---|---|
| A — Colorado woman, 30–39 | donor embryonic stem cells injected into the spinal fluid for multiple sclerosis | a clinic in Baja California, October 2022 | meningitis, with headaches and fevers; M. abscessus grew from her cerebrospinal fluid |
| B — Arizona man, 60–69 | donor embryonic stem cell injections for psoriatic arthritis | a different Baja California clinic, April 2022 | bone and joint infection of the right elbow |
| C — Colorado man, 60–69 | donor embryonic stem cell injections into both knees for osteoarthritis | a clinic in Guadalajara, October 2022 | infections in both knees |
Patient A was treated at two Colorado hospitals in November–December 2022, and infectious diseases doctors at one of them identified patients B and C in spring 2023. As of March 28, 2024, all three were still in treatment.
One clone, two distant clinics
The original bacterial isolates could be obtained only for patients A and B. Whole genome sequencing showed they were the same clone of M. abscessus subspecies massiliense, differing by a single genetic letter (single nucleotide polymorphism) — a result confirmed by regrowing and resequencing the isolates — and unlike the most common known circulating clones. Yet the two patients were treated at clinics 167 miles (269 km) apart.
Genomic comparison of the patients' isolates with known dominant circulating clones. CDC figure.
The investigation
The doctors notified their state health departments. Colorado interviewed patients A and C and Arizona interviewed patient B; Colorado searched for similar cases in Colorado and other states with CDC's help, and as of March 28, 2024 found none.
Because isolates from distant clinics were one clone, investigators suspect a common contaminated source — possibly the stem cell product, reagents or equipment. Colorado's attempts to identify the product or learn how it was given had failed; the clinics did not respond. Work with Mexican health authorities was under way.
Next steps: sequence bacteria from new samples from patient C, share the genomic data with the National Center for Biotechnology Information so future cases can be compared, and search for more cases.
The lesson
Stem cell treatments have been linked to bacterial infections before, and medical tourism carries known procedure-related risks. Health care providers and public health agencies should be aware of the risk of M. abscessus infection from stem cell treatments for uses not approved by the Food and Drug Administration, watch for similar cases, and offer guidance to people considering medical treatment abroad.
Sources
- Nguyen MH, Hasan NA, Calado Nogueira De Moura V, et al. "Notes from the Field: Potential Outbreak of Extrapulmonary Mycobacterium abscessus subspecies massiliense Infections from Stem Cell Treatment Clinics in Mexico — Arizona and Colorado, 2022." Morbidity and Mortality Weekly Report 73(18), Centers for Disease Control and Prevention.
Licence: CC0 1.0 (public domain) · Adapted from www.cdc.gov
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