Identification of bacteria present in the harvest and postharvest stages in medical cannabis (Cannabis sativa L.) grown in Colombia.

Henao-López M.; Ocampo-Nieto L.; Vargas-Alzate J.; Castro-Ríos K.; Montoya-Estrada C. · Anais da Academia Brasileira de Ciencias · 2026

**Background & Methods** This study characterized bacterial contamination in medical cannabis (Cannabis sativa L.) inflorescences from two commercial genotypes grown in Colombia during harvest and post-harvest stages. Cannabis samples were cultured on Luria Bertani agar, with bacterial isolates identified through macroscopic and microscopic analysis of axenic cultures, followed by molecular identification using 16S ribosomal region sequencing. **Key Findings** • Eleven bacterial isolates were recovered total: four during harvest (1 from Gen A, 3 from Gen B) and seven during post-harvest (5 from Gen A, 2 from Gen B), all identified as Gram-negative bacteria. • Pseudomonas sp. was the predominant bacterial genus, accounting for eight of eleven isolates (72.7%), indicating it as the most common contaminating organism across both genotypes and harvest stages. • Additional identified bacteria included members of the Enterobacteriaceae family, Stenotrophomonas panacihumi, and Agrobacterium tumefaciens complex, demonstrating diverse bacterial contamination profiles in medicinal cannabis samples from Colombian cultivation. **Dosage & Administration** Not reported. **Safety & Adverse Effects** Not reported. However, the identification of potentially pathogenic bacteria—particularly Pseudomonas sp., Enterobacteriaceae family members, and Agrobacterium tumefaciens—raises clinical concerns regarding microbial contamination in medicinal cannabis products intended for therapeutic use, as these organisms may pose risks to immunocompromised patients or cause respiratory infections if cannabis is inhaled. **Evidence Quality** This is a review-level study with significant limitations regarding clinical applicability. The research focuses solely on bacterial characterization without addressing clinical outcomes, infection rates, or pathogenic potential of identified organisms. The sample size appears limited (11 isolates from two genotypes), and no comparison with control samples or standard microbial safety thresholds is provided. Findings are specific to Colombian-grown cannabis and may not generalize to other geographic regions or cultivation practices. The study lacks information on cultivation conditions, storage parameters, or post-harvest processing methods that influence bacterial contamination. While the molecular identification methodology is sound, the absence of antimicrobial susceptibility testing, virulence factor analysis, or quantitative bacterial load data limits interpretation of actual clinical risk. This work contributes descriptive microbiological data but requires supplementation with clinical evidence and standardized safety assessments for actionable conclusions regarding medicinal cannabis safety.

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