Salmonellosis in a Patient on Natalizumab for Ulcerative Colitis and Multiple Sclerosis - Abstract
Salmonella enterica is a gram negative enteric pathogen that is acquired via oral
ingestion of contaminated food or water. Diarrheal disease caused by non-typhoidal
Salmonella serovars (NTS) such as Salmonella enteritidis results in a colitis that mimics
ulcerative colitis (UC). While NTS in immune competent adults is typically self-limiting,
NTS in those who are immune suppressed can increase the risk of bacteremia and
mortality and requires treatment with antibiotics. The use of biologic therapy in patients
with inflammatory bowel disease can lead to relapsing Salmonella infection. However,
to our knowledge there are no reports of patients who develop Salmonella infection
while on selective adhesion molecule (SAM) inhibitor class therapy. A 49-year-old
woman with well-controlled left sided UC and an 11-year diagnosis of multiple sclerosis
(MS) presented with new onset abdominal cramping, non-bloody diarrhea, rash, and
pain in her joints with stool studies positive for Salmonella enteritidis. The patient was
treated with antibiotics but had recurring symptoms and multiple positive stool cultures
requiring temporary discontinuation of natalizumab (NTZ) and an extended course of
rifaximin. NTZ is a recombinant humanized IgG4 monoclonal antibody that blocks a4
integrin, a lymphocyte adhesion molecule. It prevents chemotaxis of inflammatory cells
from the bloodstream into inflamed tissues, and thus reduces the host’s ability to clear
salmonella. We report the first case of a relapsing NTS infection in a patient on SAM
therapy, suggesting that this therapy significantly impairs the function of the innate
immune system against Salmonella infections.