A new meta-analysis finds alarming increases in colistin resistance among Acinetobacter baumannii and Pseudomonas aeruginosa across Africa, threatening the effectiveness of one of the last-resort antibiotics.
The growing threat of antimicrobial resistance has taken a concerning turn in Africa, where new research highlights rising resistance to colistin among two high-priority pathogens: Acinetobacter baumannii and Pseudomonas aeruginosa. These Gram-negative bacteria are well known for causing severe hospital-acquired infections and are increasingly resistant to multiple antibiotics, leaving clinicians with limited treatment options.
Colistin has long been considered a last-resort antibiotic, used when other therapies fail. However, this comprehensive meta-analysis, which reviewed studies from databases including PubMed, Scopus, ScienceDirect, and Google Scholar, reveals that its effectiveness is steadily eroding. The study analyzed data from 25 studies on A baumannii and 17 on P aeruginosa, focusing on clinical isolates across Africa and applying standardized susceptibility criteria.
The findings are striking. The pooled prevalence of colistin resistance was estimated at 13.75% for A baumannii and 14.42% for P aeruginosa. While these figures alone are concerning, the data also showed extremely high variability between studies, suggesting that resistance patterns differ widely depending on location and context.
Geographic differences were particularly notable. In A baumannii, resistance rates reached 18.26% in Egypt and 10.89% in South Africa, with regional variation showing the highest prevalence in East Africa at over 20%. Similarly, P aeruginosa exhibited the highest resistance in East Africa at 20.73%, compared to lower rates in North and Southern Africa.
Colistin resistance in A baumannii and P aeruginosa is rising significantly across Africa, undermining a key last-resort treatment.
Resistance rates vary widely by region, with East Africa showing the highest prevalence in both pathogens.
Urgent action—including antimicrobial stewardship, infection control, and enhanced surveillance—is needed to slow the spread of resistance.
Perhaps most alarming is the trend over time. Resistance in A baumannii nearly tripled, rising from 5.64% between 2010 and 2017 to 16.45% from 2018 to 2023. Even more dramatic, P aeruginosa resistance surged from just 2.26% to more than 30% over the same period. These increases suggest that resistance is accelerating, not stabilizing.
The implications for public health are significant. As colistin becomes less reliable, treatment options for severe infections caused by these organisms may become increasingly limited, leading to higher morbidity and mortality. The findings underscore the urgent need for coordinated efforts to address antimicrobial resistance across the continent.
Experts emphasize that robust antimicrobial stewardship programs are essential to preserve the effectiveness of existing drugs. In addition, strengthened infection prevention and control measures in healthcare settings can help reduce the spread of resistant organisms. The study also highlights the importance of expanding molecular surveillance to better understand the mechanisms driving resistance and to track its evolution over time.
Without immediate and sustained intervention, the rise of colistin resistance in these critical pathogens could mark the beginning of a post-antibiotic era in which even routine infections become difficult to treat.
