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.