Colistin-resistance among Acinetobacter baumannii and Pseudomonas aeruginosa from clinical specimens in Africa: a systematic review and meta-analysis

Background Acinetobacter baumannii and Pseudomonas aeruginosa are multidrug-resistant Gram-negative pathogens increasingly resistant to colistin, a last-resort antibiotic. This study estimated the pooled prevalence of colistin resistance among clinical isolates of these bacteria in Africa. Methods Relevant studies were retrieved from PubMed, Scopus, ScienceDirect and Google Scholar. Eligible studies reported colistin resistance in A. baumannii and P. aeruginosa from clinical specimens in Africa using EUCAST or CLSI standards. Data were analysed in STATA 17 using a random-effects model. Heterogeneity was assessed with the I2 statistic, and publication bias with Egger’s test. Subgroup and sensitivity analyses explored heterogeneity sources. Results Twenty-five studies on A. baumannii and seventeen on P. aeruginosa were included. The pooled prevalence of colistin resistance was 13.75% (95% CI: 5.99%–21.51%), for A. baumannii and 14.42% (95% CI: 3.35%–25.48%) for P. aeruginosa, both showing high heterogeneity I2 > 99%. Resistance varied significantly across countries P ≤ 0.001. In A. baumannii, prevalence was 18.26% in Egypt and 10.89% in South Africa, with regional rates of 10.9%, 13.53% and 20.05% in Southern, North and East Africa, respectively. For P. aeruginosa, regional rates were 20.73% in East, 10.85% in North and 7.19% in Southern Africa. Resistance rose over time; from 5.64% to 16.45% in A. baumannii and from 2.26% to 30.54% in P. aeruginosa between 2010–2017 and 2018–2023. Conclusions Colistin resistance in A. baumannii and P. aeruginosa is rising across Africa, emphasizing the urgent need for robust antimicrobial stewardship, infection control and molecular surveillance.