Methodological heterogeneity in mushroom extract antimicrobial research (2012-2025): a structured narrative evidence...

Mushroom (Basidiomycete) extracts have been investigated for over two decades as candidate natural antimicrobial agents amid rising concern over antimicrobial resistance, yet the comparability of this evidence base remains unresolved because assay type, solvent system, concentration units, and inoculum standardization vary widely across studies. This structured narrative evidence gap analysis maps post-2012 primary and review literature on mushroom extract antimicrobial activity, assesses whether methodological heterogeneity continues to prevent quantitative pooling, and proposes a tiered reporting framework to guide future standardization. A single-reviewer, AI-assisted search was conducted between 15 January and 30 June 2025 across major databases and Philippine institutional journal platforms, supplemented by two-generation forward and backward citation snowballing from two anchor reviews. This exercise is positioned as a preliminary gap analysis rather than a completed systematic or scoping review; no dual-reviewer screening, licensed database export, or formal risk-of-bias appraisal was performed. Eleven sources met eligibility criteria: three narrative reviews and eight primary in vitro studies. Susceptibility patterns for Gram-positive versus Gram-negative bacteria were inconsistent across the primary studies. Among studies that directly compared solvents, polar organic extracts showed greater antimicrobial activity than aqueous extracts in each of the three studies making a direct within-study comparison, though this pattern rests on a small, species- and method-heterogeneous sample and should not yet be generalised. Outcome units were not interchangeable, and reporting of replicates, inoculum density, and strain identifiers was inconsistent. The standardization gap identified over a decade earlier persists; quantitative meta-analysis is not currently supportable. A two-tier reporting framework is proposed to improve comparability and prepare future primary studies for pooled analysis, pending validation through a broader dual-reviewer systematic review with full database access.