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S. pneumoniae prominent among bloodstream infections in sickle cell disease
Despite widespread availability of penicillin prophylaxis and pneumococcal vaccines, Streptococcus pneumoniae was observed to account for the largest percentage of bacterial pathogens in bloodstream infections among children with sickle cell disease.
Previous studies have identified S. pneumoniae and Haemophilus influenzae as the leading pathogens responsible for invasive bacterial infections among the pediatric sickle cell disease population. However, after the introduction of penicillin prophylaxis and conjugated Haemophilus influenzae type b and pneumococcal vaccines, the incidence of bacterial infections in the pediatric sickle cell disease population has significantly decreased.
“Given the reported decline in the incidence of invasive S. pneumoniae and H. influenzae type b infections in the United States, new data are needed to determine the organisms responsible for [bloodstream infections] in this population,” Angela M. Ellison, MD, MSc, and colleagues at The Children’s Hospital of Philadelphia wrote. “This information would help to fine tune existing recommendations pertaining to empiric antibiotic administration in patients with [sickle cell disease] presenting with fever and reassess the effectiveness of current prophylactic strategies and to plan for future preventive strategies.”
To determine the predominant organisms responsible for contemporary bloodstream infections and associated primary infection in a pediatric sickle cell disease population after the introduction of the 7-valent pneumococcal conjugate vaccine (Prevnar, Wyeth), Ellison and colleagues performed a retrospective review of children with sickle cell disease from 2000 to 2010.
The researchers calculated the annual incidence of true bloodstream infections caused by all pathogens for each year of the study from 2001 to 2010.
In evaluating the incidence, Ellison and colleagues defined the numerator as the number of patients with a true bloodstream infection who visited the sickle cell clinic at least once during the studied year, whereas the denominator included the total number of patients who had at least one visit to the sickle cell center clinic. The incidence was reported in units of bloodstream infection episodes/1,000 clinic patients/year.
According to the review, of the 52 pathogens recovered, the most commonly isolated pathogens were S. pneumoniae (23%), coagulase-negative Staphylococcus (15%) and Salmonella species (11%).
All S. pneumoniae isolates were observed to be susceptible to ceftriaxone, whereas only 10 of the 12 isolates were susceptible to penicillin. Antibiotic susceptibility testing results were available for seven of the eight coagulase-negative Staphylococcus isolates — only one was susceptible to oxacillin. One of the five S. aureus isolates was methicillin-resistant. All Staphylococcus isolates were susceptible to vancomycin. The Salmonella species isolates all exhibited susceptibility to ampicillin and ceftriaxone.
“Progress has been made in reducing the incidence of bloodstream infections caused by virulent organisms in pediatric patients with [sickle cell disease] in the post-PCV7 era,” Ellison and colleagues wrote. “However, we expect that bloodstream infections will continue to occur because of factors such as serotype replacement, suboptimal adherence and/or effectiveness of penicillin prophylaxis and the more recent use of [central venous access devices] in the [sickle cell disease] population. Continued use of empiric, broad-spectrum antibiotics in sickle cell disease patients with fever or suspected infection is warranted.”
Disclosure: The researchers reported no relevant financial disclosures.
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