1323. Laboratory Abnormalities in Children Undergoing Outpatient Therapy for Staphylococcus aureus Acute Hematogenous Osteomyelitis: Should We Worry?


 
 
 Recent PIDS practice guidelines for acute hematogenous osteomyelitis (AHO) advocate for regular laboratory monitoring for adverse drug events. Data are limited however with respect to the frequency or clinical impact of antibiotic-related laboratory abnormalities (ARLA) in pediatric AHO. We reviewed the experience with ARLA in children undergoing treatment for S. aureus AHO.
 
 
 
 Cases of S. aureus AHO in children were reviewed from 2011-2020. Eligible cases were those 1) discharged to complete therapy at home (IV or oral), 2) with baseline complete blood count (CBC), creatinine and AST/ALT obtained during the hospitalization and 3) at least one CBC, creatinine, and/or AST/ALT measurement in the outpatient setting while receiving AHO therapy. Neutropenia, thrombocytopenia and AST/ALT elevation were defined using the NIH DAIDS pediatric toxicity grading system; acute kidney injury (AKI) was defined using pRIFLE.
 
 
 
 207 subjects met inclusion criteria. Outpatient CBC was obtained in 187 subjects, creatinine in 121 and AST/ALT in 63. Patients with and without ARLA were similar with respect to age and demographics. Neutropenia developed in 12 (6.4%) and thrombocytopenia in 5 (2.7%) at a median of 23 and 18 days of therapy, respectively (Figures 1). Outpatient hematologic abnormalities were more common among subjects with MRSA, history of inpatient ARLA and those receiving certain antibiotics, specifically vancomycin (Figures 2, 3). There was no clear relationship with hematologic abnormalities and vancomycin daily dose. Neutropenia prompted modification of therapy in 1 case. No infections or bleeding events were attributable to ARLA. Three cases of outpatient AKI occurred (2.1% [vancomycin, n=1; cefazolin, n=2]); one subject had therapy discontinued. Outpatient AST/ALT elevation occurred in six (9.5%), none of which were symptomatic. Patients with AST/ALT elevation were disproportionately treated with cefazolin (p=0.006).
 Panel A. The number of patients experiencing antibiotic-related laboratory abnormalities (ARLA). Panel B. Box plots depicting the timing of ARLA relative to initiation of antimicrobial therapy.
 
 
 
 ARLAs, particularly neutropenia, are common in patients receiving outpatient therapy for AHO after 2-3 weeks of therapy. However, the majority of ARLA are mild and do not result in symptoms or modification of therapy. Further study is necessary to appreciate how these findings might be applicable to all cause osteomyelitis.
 
 
 
 Jonathon C. McNeil, MD, Agency for Healthcare Research and Quality: Grant/Research Support|Allergan: Provided reagents for unrelated research|Nabriva: Site investigator for multicenter clinical trial Sheldon L. Kaplan, MD, MeMed: Grant/Research Support|Pfizer: Grant/Research Support.
