Procalcitonin level accurate biomarker for invasive bacterial infection

A retrospective study in more than 1,000 well-appearing infants aged younger than 3 months with fever without a source (FWS_ found that procalcitonin (PCT) performs better than C-reactive protein (CRP) in identifying patients with invasive bacterial infections (IBIs), which are positive bacterial cultures of cerebral spinal fluid (CSF) or blood, and seems to be the best marker for ruling out IBIs.

The study was conducted in infants admitted to 7 Spanish and Italian pediatric emergency departments in which standard protocol for such infants included urine dipstick (UD) testing, measurement of CRP and PCT levels, white blood count (WBC), and obtaining blood and urine cultures.

A total of 289 infants (26%) were diagnosed with a definite serious bacterial infection (positive bacterial culture of CSF, blood, urine, or stool) and 23 (2.1%) with an IBI. Previously identified risk factors were compared in patients with and without IBI, including specified levels of PCT and CRP, WBC, and absolute neutrophil count. Only PCT 0.5 ng/mL or higher was found to be an independent risk factor for IBI. Investigators also conducted a separate analysis in infants with fever of recent onset and a normal UD, which showed that PCT level was the best marker for identifying IBIs in these patients (Gomez B, et al. Pediatrics. 2012;130[5]:815-822).

Commentary

Is procalcitonin readily available in the hospital or emergency room where you see patients? If so, I suggest a trial inclusion of this test in your evaluation of certain patients. Procalcitonin is not a perfect test, but after 10 years of studies, it seems to be the best we have for now. It may have a role in how we answer the age-old question in pediatrics: Is this febrile child “sick” or “not sick”?  -Michael Burke, MD