Johns Hopkins Children’s Center specialists report they have successfully treated and put in remission a 2-year-old, now age 5, with a highly virulent form of tuberculosis known as XDR TB, or extensively drug-resistant TB. The case, researchers say, provides the first detailed account of a young child in the United States diagnosed and treated for XDR TB.

The bug’s resistance to most known TB drugs render it particularly challenging to treat in anyone but even more so in children, the Johns Hopkins team says, with only a handful of cases of children younger than 5 described in the medical literature worldwide.

Despite the successful outcome, the Johns Hopkins experts say the child’s case underscores the shape-shifting nature of a bacterium increasingly resistant to drugs, and the serious challenges of monitoring and treating pediatric TB.

“We are thrilled that our patient is doing so well,” says Johns Hopkins Children’s Center pediatrician and TB expert Sanjay Jain, MD. “But at the same time, this is a wake-up call to the realities of TB.”

In an account of the case, published online Nov. 16 in The Lancet Infectious Diseases, the Johns Hopkins team describes the hurdles they faced throughout the child’s treatment along with several “pearls” of clinical wisdom gleaned from it.

Mycobacterium tuberculosis, the bacterium responsible for TB, is estimated to cause almost 10 million new cases of TB disease worldwide each year, with strains impervious to drug therapies rapidly spreading. Experts estimate that a million children develop TB each year, but the real number may be higher given the difficulty of confirming the diagnosis in a child.

“Drug-resistant TB is a daunting disease to diagnose and treat in anyone, but in a child, it is infinitely more so,” says Nicole Salazar-Austin, MD, co-author on the report and a fellow in pediatric infectious disease at the Johns Hopkins University School of Medicine.