A Systematic Review of the Utility of Procalcitonin in Bacterial Meningitis

Purpose/Objective: To review the utility of procalcitonin (PCT) in the management of bacterial meningitis (BM). Methods: An English-language MEDLINE search from 1964 through June 20, 2018 was completed using the following search terms: calcitonin, calcitonin gene-related peptides, meningitis: bacterial/diagnosis, and meningitis, bacterial/blood. Primary literature that evaluated the diagnostic value of PCT in adult patients for separating BM from viral or aseptic meningitis and studies comparing PCT with other biomarkers were included. Studies that did not consider antibiotic pretreatment as an exclusion criterion were excluded. Results: A total of 15 studies were identified for inclusion in this review. Ten studies evaluated the utility of PCT in distinguishing BM from non-bacterial meningitis (NBM) in a total of 1022 patients. Eight of these were prospective studies and two were retrospective. All 10 studies showed that PCT is significantly elevated in cases of BM compared to NBM, with the average elevation ranging from 0.5 ng/mL to 4.714 ng/mL in the serum and 0.2 ng/mL to 1.88 ng/mL in the cerebrospinal fluid (CSF). Three studies compared the diagnostic value of serum PCT versus non-serum PCT. All three studies were prospective clinical studies and included a total 502 patients. Two studies showed that serum PCT had a higher diagnostic value compared to CSF PCT and only one showed that CSF PCT is superior. Finally, no studies reviewed the use of PCT in guiding antibiotic de-escalation and no studies reviewed whether to use PCT in parallels or in series. However, two studies considered the use of PCT in guiding antibiotic usage and one study examined the use of PCT in conjunction with lactate. These studies showed that there are higher levels of CSF PCT in patients with gram-negative infections compared to those with gram-positive infections and explored the possibility of using PCT in addition to glucose to guide antibiotic therapy. Lastly, one study showed that there is higher specificity when using PCT with lactate in series and higher sensitivity when used in parallel. Conclusions: PCT is a useful biomarker in identifying cases of BM and serum PCT may be better than CSF PCT in identifying BM. However, larger studies are necessary to confirm these results and identify a standardized threshold. Additionally, more studies are necessary to explore the best way to utilize PCT and in diagnosing BM and the utility of PCT in guiding antibiotic therapy for BM.