Study: Is imaging always needed in Staphylococcus aureus bacteremia?

The answer is "no," according to investigators who studied if children with uncomplicated Staphylococcus aureus bacteremia (SAB) can be distinguished from those with deep-seated infections.

The retrospective case-control study was conducted on all children with SAB admitted to a tertiary-care pediatric center in Cleveland from 1992 to 2006. Of 298 children, 249 (84%) had one or more underlying conditions, most often immunocompromised status, prematurity, or known congenital heart disease. Almost 75% of the 298 had at least one study performed-64% an echocardiogram, 39% abdominal imaging, and 35% bone imaging. Fifty-six children (19%) had all three.

Whereas 219 subjects (81%) had uncomplicated SAB, the remaining 58 (19%) showed evidence of deep-seated infection. Of the latter group, most either had congenital heart disease or indications of infection at presentation, with osteomyelitis the most common diagnosis. Only 11 subjects (3.7%) had unsuspected deep-seated infections, with no symptoms or no preexisting structural heart abnormalities.

Commentary:

Testing, it seems, is not necessary in all patients, but may be indicated in some. Based on this study, when faced with a blood culture positive for S aureus, I would screen first with a physical exam focused on heart, bone, and abdomen. If that is normal, I would screen children with prematurity, known congenital heart disease, and, particularly, those with a second positive blood culture.

In this study, about 16% of the SAB was caused by methicillin-resistant S aureus (MRSA). How many had community-acquired MRSA is not clear. I wonder if the same study begun today would show more of this type of MRSA, and if that would change the results. It seems to me that staph bacteremia is more common now, even in seemingly normal hosts.

DR. BURKE, section editor for Journal Club, is chairman of the department of pediatrics at Saint Agnes Hospital, Baltimore. He is a contributing editor for Contemporary Pediatrics. He has nothing to disclose in regard to affiliations with, or financial interests in, any organization that may have an interest in any part of this article.