title: Impact of antibiotic pretreatment on bone biopsy yield for children with acute hematogenous osteomyelitis.
abstract: OBJECTIVE
  Pediatric acute hematogenous osteomyelitis (AHO) is a relatively common reason for hospitalization, but many variables require additional study, including the impact of antibiotic treatment on bone biopsy culture yield.
  
  
  METHODS
  This was a retrospective study of children 60 days to 18 years old with AHO seen from 2011 to 2012 in whom bone biopsy cultures were obtained.
  
  
  RESULTS
  A total of 67 children had biopsies; median age was 7 years; 40 were pretreated with antibiotics. Microbiologic confirmation was obtained for 72%: in 34%, both blood and bone cultures were positive; in 33%, bone cultures alone were positive; and 4% had only positive blood cultures. There was no difference in bone biopsy cultures for children who did and did not receive antibiotics before biopsy (28/40 [70%] vs 17/27 [63%], odds ratio 1.37, 95% confidence interval 0.49-3.86). For pretreated patients, the mean duration of therapy was longer in children with negative cultures (79 vs 40 hours, P=.04). Bacteremia was seen in 26 (39%), and was more common in antibiotic-pretreated children (55% vs 15%, odds ratio 7, 95% confidence interval 2.1-24.1). Among the 41 nonbacteremic children, bone cultures provided the only microbiologic diagnosis for 22 (54%): 20 Staphylococcus aureus, 2 Streptococcus pyogenes.
  
  
  CONCLUSIONS
  In conclusion, although bone biopsy results were not affected by previous antibiotic administration, a longer duration of antibiotic therapy before bone biopsy was associated with lower culture yield. In one-third of children, only the bone biopsy resulted in an organism being isolated. As it may take longer to sterilize bone than blood, a bone biopsy/culture should be considered a crucial part of the AHO evaluation to increase diagnostic yield.
authors.affiliation: Sections of Hospital Medicine.
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Zhorne
authors.affiliation: Sections of Hospital Medicine.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Altobelli
authors.affiliation: Emergency Medicine, and Infectious Diseases, Department of Pediatrics, Baylor College of Medicine, Houston, Texas acruz@bcm.edu.
authors.forename: Andrea T
authors.initials: AT
authors.lastname: Cruz
mesh_terms: D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D019072:Antibiotic Prophylaxis / Q000706:statistics & numerical data*; D016470:Bacteremia / Q000150:complications / Q000517:prevention & control*; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010019:Osteomyelitis / Q000150:complications / Q000473:pathology*; D012189:Retrospective Studies
chemical_list: D000900:Anti-Bacterial Agents
keywords: antibiotic pretreatment; culture yield; osteomyelitis; pediatric