Prevalence of colistin resistance in non-clinical Pseudomonas aeruginosa isolates: A systematic review and meta-analysis

Background Pseudomonas aeruginosa is a significant opportunistic pathogen responsible for a wide range of infections. The growing prevalence of antimicrobial resistance in clinical settings has led to a greater reliance on last-resort agents such as colistin. Notably, such antibiotics have long been used in veterinary practices, possibly playing a role in the emergence of resistance. However, despite the growing concern over colistin resistance, no previous systematic review and meta-analysis has estimated the global prevalence of colistin-resistant P. aeruginosa in non-clinical samples. This study aimed to assess the global prevalence of colistin resistance in P. aeruginosa isolates from non-clinical sources through a systematic review and meta-analysis. Methods A comprehensive literature search was conducted in PubMed, Web of Science, and Scopus for studies published up to January 2025. Eligible studies reporting colistin resistance in P. aeruginosa from environmental, animal, or food-related samples were included. A random-effects meta-analysis was used to estimate the pooled prevalence of resistance. Subgroup analyses were performed based on publication year, continent, country, testing guidelines, antimicrobial susceptibility testing methods, and sample source. Results A total of 70 studies were included. The pooled global prevalence of colistin resistance in non-clinical P. aeruginosa isolates was 5% (95% CI: 1–10%), with substantial heterogeneity (I 2 = 97%). Subgroup analyses revealed significant variations: the highest resistance was observed in milk samples (47%, 95% CI: 3–94%), in North America (18%, 95% CI: 0–69%), and in Turkey (30%, 95% CI: 0–100%). Resistance increased over time from 7% in 2013 to 21% in 2024 (a 14% increase). No significant publication bias was detected (Egger’s test p = 0.54). Conclusion The rising prevalence of colistin resistance in non-clinical P. aeruginosa isolates underscores the urgent need for enhanced antimicrobial surveillance. Standardizing susceptibility testing methods and restricting colistin use in veterinary settings are essential steps to preserve its efficacy and limit the spread of resistance.