A single institutional review of pediatric Bacillus spp. bloodstream infections demonstrates increased incidence among children with cancer

Background: Bacillus species are known to cause severe infection in immunocompromised hosts. The incidence of Bacillus bloodstream infections and characteristics of infection among children with cancer or indication for hematopoietic cell transplant (HCT) is unknown.

Methods: We performed a retrospective medical record review of all cases of Bacillus bacteremia between January 1, 2005, and December 31, 2014, at Boston Children's Hospital. We report average incidences from 2012 to 2014. We performed a detailed review of infections among children with cancer or undergoing HCT and a case-control study to evaluate whether neutropenia at diagnosis caries higher risk of Bacillus infection for children with acute lymphoblastic leukemia (ALL).

Results: One hundred fourteen children developed Bacillus bacteremia during the study period, with an estimated incidence of 0.27/1,000 patients. Among children treated for cancer or undergoing HCT, there were 37 bloodstream infections (2.0/1,000 patients). Of the 37 oncology/HCT patients, oncologic diagnoses included ALL (18), acute myeloid leukemia (3), myelodysplastic syndrome (1), solid tumors (8), and 7 children were undergoing HCT. The incidence of infection among children with ALL was 34/1,000 patients and all central nervous system (CNS) infections (6) and deaths (3) occurred in this population. Neutropenia at time of diagnosis in children with ALL was not associated with risk of infection (P = 0.17).

Discussion: We report the first hospital-wide analysis of Bacillus infection and found that immunocompromised children experience a significant proportion of Bacillus infections. Children with ALL have a high incidence of infection and are at higher risk of CNS involvement and death.