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You are seeing a 2.5 month old baby who underwent a fever work-up yesterday and has been called back due to a positive blood culture growing gram positive cocci in clusters. The baby received the first set of immunizations at age 7 weeks. The baby is afebrile today and has been doing well and eating normally. The only treatments have been acetaminophen, last given 8 hours ago.
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October 30, 2019 at 5:17 am
C) Gram positive cocci in clusters makes it more likely that the culture is a contaminant
Occult bacteremia in high-risk febrile infants occurs at a rate of 0.7% or less in the post-Prevnar era. Conversely, approximately 2.8% of blood cultures obtained as part of occult bacteremia work-ups are false positives (contaminants). Over-treating as a response to these culture results can lead to unnecessary procedures, adverse effects, and healthcare costs. Gram positive cocci in clusters may be the pathogen Staph aureus, but is more likely to be coagulase negative staph, the most common blood culture contaminant in this scenario. Gram positive cocci in chains is likely to be streptococci, and strep pneumoniae is a common true pathogen in this scenario (group B strep is not as common by the age of 2.5 months). Cultures that are positive in < 24 hours are associated with a higher likelihood of being a true positive.