Sickle Cell Disease: Salmonella Is the New Leading Cause of Bacterial Infections

Jim Kling

June 02, 2021

Among children with sickle cell disease who have not undergone hematopoietic stem cell transplant, Salmonella is now the leading cause of invasive bacterial infection (IBI), according to a new retrospective study (BACT-SPRING) conducted in Europe. Streptococcus pneumoniae was the second most common source of infection, marking a shift from years past, when S. pneumoniae was the most common source. The epidemiology of IBI in Europe has been altered by adoption of prophylaxis and the introduction of the pneumococcal conjugated vaccine (PCV13) in 2009.

Previous studies of IBI have been single center with small sample sizes, and few have been conducted since 2016, said Jean Gaschignard, MD, PhD, during his presentation of the study at the annual meeting of the European Society for Paediatric Infectious Diseases, held virtually this year.

Gaschignard is head of pediatrics at Groupe Hospitalier Nord Essonne in Longjumeau, France.

The study produced some unexpected results. "We were surprised," said Gaschignard, by results indicating that not all children aged under 10 years were undergoing prophylaxis. Instead, the figures were closer to 80% or 90%. Among children over 10, the rate of prophylaxis varies between countries. "Our study is a clue to discuss again the indications for the age limit for prophylaxis against pneumococcus," said Gauschignard, during the question-and-answer session following his talk.

The data give clinicians an updated picture of the epidemiology in this population following introduction of the PCV13 vaccine. "It was very important to have new data on microbiology after this implementation," said Marie Rohr, MD, who is a fellow in pediatric infectious diseases at the University Hospitals of Geneva. Rohr moderated the session where the study was presented.

Rohr noted the shift from the dominant cause of IBI after the introduction of the PCV10/13 vaccine, from S. pneumoniae to Salmonella. The researchers also found a preponderance of bacteremia and osteoarticular infections. "The mortality and morbidity are still considerable despite infection preventive measures," said Rohr.

The results should also prompt a second look at prevention strategies. "Even if the antibiotic prophylaxis is prescribed for a large [proportion of children with sickle cell disease] under 10 years old, the median age of invasive bacterial infection is 7 years old. This calls into question systematic antibiotic prophylaxis and case-control studies are needed to evaluate this and possibly modify antibiotic prophylaxis recommendations in the future," said Rohr.

The BACT-SPRING study was conducted between Jan. 1, 2014, and Dec. 31, 2019, using online data. It included 217 IBI episodes from 26 centers in five European countries. Just over half were from France, while about a quarter occurred in Spain. Other countries included Belgium, Portugal, and Great Britain. Participants were younger than 18 and had an IBI confirmed by bacterial culture or PCR from normally sterile fluid.

Thirty-eight episodes occurred in children who had undergone hematopoietic stem cell transplantation (HSCT), and 179 in children who had not undergone HSCT. The presentation focused exclusively on the latter group.

Among episodes in children without HSCT, the mean age was 7. Forty-eight patients had a history of acute chest syndrome, 47 had a history of ICU admission, 29 had a history of IBI, and 27 had a history of acute splenic sequestration. Thirteen underwent a splenectomy. Almost half of children had none of these characteristics, while about one-fourth had two or more.

In the HSCT group, 141 children were on prophylaxis at the time of the infection; 74 were on hydroxyurea, and 36 were currently or previously on a transfusion program. Sixty-eight cases were primary bacteremia and 55 were osteoarticular. Other syndromes included pneumonia empyema (n = 18), and meningitis (n = 17), among others. In 44 cases, the isolated bacteria was Salmonella, followed by S. pneumoniae in 32 cases. Escherichia coli accounted for 22. Haemophilus influenza was identified in six episodes, and group A Streptococcus in three.

The study is the first large European epidemiologic study investigating IBI in children with sickle cell disease, and one of its strengths was the strict inclusion criteria. However, it was limited by its retrospective nature.

Gaschignard and Rohr have no relevant financial disclosures.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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