Klebsiella pneumoniae

Klebsiella pneumoniae has become the poster child for antibiotic resistance acquisition, demonstrating how horizontal gene transfer can outpace human pharmaceutical development. This bacterium collects resistance genes like a curator assembles a collection—methodically, comprehensively, and with devastating effectiveness. Some K. pneumoniae strains now carry resistance to virtually every available antibiotic, including last-resort drugs like carbapenems and colistin. These 'superbugs' didn't evolve this resistance through slow mutation; they acquired it through plasmid transfer from other bacteria.

The bacterium's success stems from its promiscuity in genetic exchange and its ability to maintain multiple large plasmids simultaneously. Where E. coli might carry one or two resistance plasmids, K. pneumoniae routinely harbors several, each encoding different resistance mechanisms. This genetic hoarding strategy provides redundancy—if one resistance mechanism fails, others remain. The bacterium also excels at biofilm formation, creating protected communities where horizontal gene transfer occurs at elevated rates and antibiotic penetration is limited.

K. pneumoniae's trajectory illustrates the Red Queen dynamic in accelerated form. As hospitals deploy new antibiotics, the bacterium acquires corresponding resistance genes, often within months of drug introduction. This arms race has fundamentally changed hospital infection control, transforming what was once a manageable pathogen into an existential threat for immunocompromised patients. The lesson for any competitive environment: when your opponent can acquire and integrate external innovations faster than you can develop new ones, competitive advantage becomes fleeting.