Acinetobacter baumannii

Acinetobacter baumannii earned the nickname 'Iraqibacter' during the Iraq War, when it caused devastating wound infections in military personnel. But this bacterium's rise reflects broader healthcare dynamics: the creation of hospital environments where antibiotic pressure, immunocompromised patients, and invasive devices create perfect conditions for resistant pathogens. Like Pseudomonas aeruginosa, A. baumannii excels at biofilm formation on medical equipment and has acquired resistance to virtually every antibiotic class.

A. baumannii's survival strategy centers on persistence. The bacterium can survive desiccation on hospital surfaces for months—far longer than most bacteria. This environmental hardiness, combined with biofilm formation on ventilators, catheters, and other devices, creates reservoirs for ongoing transmission. Once established in an ICU, A. baumannii is extraordinarily difficult to eradicate. Outbreaks have forced entire unit closures for deep cleaning, yet the organism often returns.

The bacterium's resistance acquisition demonstrates genomic plasticity rivaling any species. A. baumannii genomes contain 'resistance islands'—large chromosomal regions packed with antibiotic resistance genes acquired through horizontal transfer. Some strains carry over 40 different resistance mechanisms, creating pan-resistant organisms untreatable with any available drug. This genetic hoarding appears to incur little fitness cost, allowing resistant strains to persist even without antibiotic pressure. A. baumannii thus represents the endpoint of hospital adaptation: an organism optimized for survival in the very environments designed to eliminate pathogens.