Serum Procalcitonin in Culture-Confirmed Melioidosis: A Systematic Review and Meta-Analysis with Narrative Evaluation of Clinical and Prognostic Implications

Background: Procalcitonin (PCT) is a biomarker of bacterial infection and sepsis severity, but its role in melioidosis remains unclear. This study aimed to synthesize available evidence on serum PCT levels in culture-confirmed melioidosis and explore associations with disease severity and mortality. Methods: We conducted a systematic review following PRISMA guidelines and registered the protocol with PROSPERO (CRD420251166979). PubMed, Embase, and Scopus were searched up to 30 October 2025. Observational studies reporting serum PCT levels in microbiologically confirmed melioidosis were included. Study quality was assessed using the Newcastle–Ottawa Scale (NOS) for observational studies. Random-effects models were used to calculate pooled mean PCT levels, with heterogeneity assessed by I2. Sensitivity analyses were performed to explore the influence of historical and small-sample studies. Results: Seven studies comprising 284 patients with culture-confirmed melioidosis were included. The pooled mean PCT level was 14.46 ng/mL (95% CI: 4.59–24.33), with substantial heterogeneity (I2 = 87.7%). Sensitivity analyses excluding the oldest study and the smallest sample size reduced heterogeneity but retained consistently elevated PCT levels across cohorts. Higher PCT concentrations were consistently observed among patients with septic shock, bacteremia, and fatal outcomes, although variability in definitions precluded quantitative synthesis of prognostic effect sizes. These findings were based on heterogeneous study-level comparisons and could not be synthesized quantitatively. Conclusions: PCT is markedly elevated in melioidosis and reflects the severity of systemic infection, supporting its potential role as an adjunctive biomarker for early risk stratification. However, substantial heterogeneity and limited sample sizes prevent the establishment of a melioidosis-specific prognostic threshold. Standardized, prospective, multicenter studies are required to clarify the independent prognostic value of PCT in melioidosis management. This study establishes a pooled estimate of serum PCT levels in melioidosis and demonstrates that these values are comparable to those observed in severe bacterial sepsis, supporting its interpretation as a marker of systemic inflammatory burden rather than a disease-specific biomarker.