PURPOSE OF THE STUDY.
To describe a new infectious disease phenotype in patients who inherit mutations in the interleukin 12 (IL-12) signaling pathway.
In this report the authors documented sepsis with Klebsiella pneumoniae in 2 unrelated patients with complete defects in the IL-12 receptor β1.
This was a chart review with case reports.
The first patient was born to unrelated parents and developed BCGitis after BCG vaccination in infancy followed by nontyphoidal salmonellosis. Both infections were difficult to treat despite multiple appropriate antimicrobial agents administered over 26 months. This was followed by development of disseminated Mycobacterium bovis infection, which also responded poorly to multidrug antimicrobial agents along with interferon γ therapy. The patient's condition worsened, and he developed systemic infection with Candida albicans and with K pneumoniae, which ultimately proved to be fatal despite aggressive and appropriate antimicrobial therapy. The second patient was born to consanguineous parents and did not receive the BCG vaccine, but at the age of 14 months she developed multiple adenopathies that stained for Nocardia nova; she also developed a positive blood culture for K pneumoniae. The initiation of appropriate antimicrobial agents and interferon γ resulted in resolution of her infections.
Klebsiella infections should be considered in patients with IL-12 receptor β1 deficiency. In addition, IL-12 receptor β1 should be considered in patients with unexplained klebsiellosis.
This is another example of the expanding range of microbial pathogens that can be observed in patients with defects that affect the IL-12 pathway. The historical observation that these patients primarily are affected by mycobacterial and salmonella infections needs to be modified to include mucocutaneous disease with C albicans seen in up to 25% of these patients and now also Klebsiella infection. This again points out that clinicians should be wary of not considering a specific defect caused by an infectious organism that does not fit with the initial or “classical” description of infections associated with a genetic defect. These disorders should be considered a “work in progress” in terms of the clinical phenotype. As with all rare diseases, it is best to consult with an experienced clinical immunologist when a child presents with an unusually severe or persistent infection.
- Copyright © 2011 by the American Academy of Pediatrics