The Clock Running Against Us

Antibiotics occupy a strange position in medicine. Almost every other drug works about as well on its ten millionth prescription as on its first. Antibiotics do not. Every course, everywhere, applies pressure that favors the bacteria able to survive it. The drug erodes its own future simply by being used. This is what makes antimicrobial resistance one of the largest slow-moving problems in medicine, and one of the least dramatic to report.

Why resistance moves faster than you would expect

Bacteria reproduce in minutes rather than years, so mutations accumulate quickly. But the more important mechanism is one that has no equivalent in humans. Bacteria can hand resistance genes sideways to completely unrelated bacteria, carried on small loops of DNA called plasmids that move freely between cells1. A resistance gene that arises in one species can appear in a completely different one without any shared ancestry.

This is why intuitions borrowed from ordinary evolution understate the speed of the problem. Resistance does not merely descend through generations. It circulates.

The best possible new antibiotic is one almost nobody is allowed to use.

The pipeline problem is economic, not scientific

A drug for a chronic condition is taken daily, perhaps for decades. An antibiotic is taken for a week. Worse, a genuinely powerful new antibiotic will be deliberately held in reserve and used as rarely as possible, precisely to delay resistance. Good stewardship and commercial return point in opposite directions, and the result is that large pharmaceutical companies have largely left the field. The scientific difficulty is real, but the incentive structure is the deeper reason the pipeline thinned.

Genuinely new classes, finally

Against that background, the recent arrivals matter. Gepotidacin, approved in March 2025 for uncomplicated urinary tract infections, is the first approved member of a new chemical class. It jams the same bacterial enzymes that fluoroquinolones target, the older family that includes drugs like ciprofloxacin, but grips them at a different point, which lets it work on bacteria that have already learned to resist those drugs. Approved4 In December 2025 it was joined by zoliflodacin, a single-dose oral treatment for gonorrhea, an infection where resistance has been closing off options for years.

Further back in development, zosurabalpin represents something rarer still: an entirely new class that works by blocking the transport of lipopolysaccharide, a material the bacterium needs to build its outer wall. In trials Its target is Acinetobacter baumannii, a hospital pathogen the World Health Organization ranks at its highest priority level and which resists nearly everything currently available.

Buying time, not winning

A review of the antibiotics approved between 2017 and 2025 found that resistance mechanisms had already emerged against them, frequently by repurposing genetic machinery the bacteria already had. This is the pattern rather than the exception. New drugs extend the timeline; they do not end the problem. That is why stewardship, rapid diagnostics that avoid unnecessary prescriptions, infection control, and surveillance are not secondary to drug discovery. They are what determines how long each new drug lasts.