Nurse Practitioners wrote 5,364,113 antibiotic claims in 2023. Infectious Disease specialists wrote 271,821. That gap, nearly 20 to one, is the defining feature of outpatient antibiotic prescribing in Medicare today.

The comparison is not entirely fair on its face. There are 80,376 distinct NP antibiotic prescribers versus just 3,509 Infectious Disease specialists, so raw volume differences are expected. But the per-prescriber numbers still tell a striking story: NPs averaged 66.7 antibiotic claims each, while ID specialists averaged 77.5. The volume gap is almost entirely a function of workforce size, not individual prescribing intensity. And the workforce gap has been widening for a decade.

A Decade of Shifting Prescribing Authority

In 2013, Infectious Disease specialists accounted for 14.65% of combined NP-and-ID antibiotic claims. By 2022, that share had fallen to 6.85%, while NPs held 93.15%. Over the same period, NP antibiotic claims grew from 2,235,178 to 7,152,238.

That trajectory reflects two simultaneous forces: NPs gained broader prescribing authority across more states, and the Medicare-enrolled population aged into a demographic that sees primary care providers, not specialists, for most acute infections. The practical result is that the specialty with the deepest training in resistance patterns and treatment failure now writes a shrinking fraction of the antibiotic claims in the program.

For antibiotic stewardship, the math matters. Every percentage point of ID specialist share that transfers to less specialized prescribers represents thousands of prescribing decisions made without the same depth of pathogen-specific knowledge. Whether those decisions are clinically equivalent is a question the claims data cannot answer, but the scale of the shift means the answer has real consequences for resistance trends.

The Cost Signal Points in an Unexpected Direction

One number cuts against the simple narrative that NP prescribing is less careful: the average cost per antibiotic claim was $10.48 for Nurse Practitioners versus $30.68 for Infectious Disease specialists in 2023.

The cost difference almost certainly reflects case mix, not prescribing efficiency. ID specialists treat more complex infections, resistant organisms, and patients who have already failed first-line therapy. Those cases call for broader-spectrum or newer agents that carry higher price tags. NPs, by contrast, are more likely to be treating uncomplicated urinary tract infections, upper respiratory infections, and skin infections where amoxicillin or a generic fluoroquinolone is appropriate and cheap.

That case mix logic is also the strongest argument for the current distribution of prescribing. Routine infections should be handled in primary care. Specialists should be reserved for cases that need them.

Where the Stewardship Gap Actually Lives

The stewardship debate has centered on hospitals, where formulary controls, pharmacist review, and ID consultation are standard. Outpatient Medicare is a different environment. There are no automatic checks when an NP writes a tenth-day course of azithromycin for a patient with a viral upper respiratory infection. The volume is enormous and the oversight is thin.

ID specialists' share of combined NP-and-ID antibiotic claims fell from 14.65% in 2013 to 6.85% in 2022. That decline does not mean ID specialists are being bypassed on cases they should own. But it does mean that as NP prescribing volume grows, the proportion of antibiotic decisions made with specialist input keeps shrinking. At 5,364,113 NP claims per year, even a small rate of inappropriate prescribing represents a large absolute number of unnecessary antibiotic courses.

The question that the data raises but cannot resolve: as ID specialists' share of outpatient antibiotic prescribing continues to fall, does the Medicare program have any mechanism to distinguish the routine cases that NPs handle appropriately from the complex ones that warrant specialist involvement before a prescription is written?