Follow-up blood cultures in Staph aureus bacteremia rarely positive

1. In children with S. Aureus bacteremia (SAB), follow up blood cultures (FUBCs) after two negative cultures were rarely positive.

2. Patients with osteomyelitis or endocarditis were more likely to have intermittent or prolonged positive blood cultures

Evidence Rating Level: 2 (Good)

Study Rundown: Staphylococcus aureus is a common and dangerous pathogen associated with bloodstream infections in children. There is no evidence-based consensus regarding how many negative blood cultures are required to show clearance of SAB. This study analyzed children with SAB who were hospitalized in the Texas Children’s Hospital network in 2018. Despite being limited by small sample size, it found that less than 5% of patients had intermittent positive cultures (defined as a positive culture that followed and preceded a negative blood culture) and only 1% percent of children had a positive result after two negative FUBCs. Furthermore, intermittent and prolonged (≥3 days) positive cultures were associated with more serious SAB complications such as osteomyelitis and endocarditis. These results show that two documented negative blood cultures likely suffice in proving bacterial clearance. Application of these findings would prevent unnecessary blood draws on children, reducing both hospital costs and trauma to patients.

Click to read the study in Pediatrics

Relevant Reading: Sending repeat cultures: is there a role in the management of bacteremic episodes

In-Depth [retrospective cohort]: This study analyzed medical records of 122 pediatric patients with documented SAB who were hospitalized at the Texas Children’s Hospital network between January 1st and December 31st, 2018. A median of 2 negative FUBC results were collected to document resolution of infection. Only 48 out of 122 patients had three or more FUBCs collected. Intermittent positive cultures were seen in 6 patients, with only 1 patient having a repeat positive blood culture after 2 documented FUBCs. All 6 of these patients had osteomyelitis or endocarditis (p= 0.04).

Early source control was shown to be a critical variable in determining the risk of having intermittent positive blood cultures. Every patient with SAB osteomyelitis and intermittent positive blood cultures (n = 4) had surgical debridement greater than 24 hours after the initial blood culture was drawn or required more than one debridement. In those with SAB osteomyelitis whose FUBCs remained negative (n = 33), only 2 patients had debridement > 24 hours after the initial blood cultures were drawn, and only 6 required > 1 debridement.

Image: PD

©2020 2 Minute Medicine, Inc. All rights reserved. No works may be reproduced without expressed written consent from 2 Minute Medicine, Inc. Inquire about licensing here. No article should be construed as medical advice and is not intended as such by the authors or by 2 Minute Medicine, Inc.