Should intensivists prescribe fewer antibiotics?

And in whose interests should we ask the question?

Antibiotics are easier to start than stop, especially in the ICU. Critically ill patients have a high prevalence of infection on presentation, which is usually impossible to identify or rule out definitively at first.

What is the indication for broad-spectrum antibiotics, someone asks you? “Empiric,” which translates roughly as “I don’t know, and don’t ask me about it again until Tuesday.”

As active infection appears less likely, standard practice includes “de-escalation” of antibiotics. This is an odd choice of phrase, one that’s more commonly used to describe efforts to prevent a tense conflict from boiling over into violence. No one should care about MIC tables and antibiograms that much.

In the ICU, where antibiotics have typically already been nearly maximized, “de-escalation” is not the goal; narrowing and stopping them is.

But returning to first principles for a moment: why?

Physicians Have No Duty to Reduce Antibiotic Use

Physicians have a fiduciary duty to their patients, treated individually. In today’s complex, corporately managed healthcare systems, it’s easy to lose sight of that foundational principle.

In the context of antimicrobial use, this implies prescribing the best agent(s) available at doses and durations that the physician considers maximally beneficial, balanced against the competing risks of harm to the patient from adverse reactions or other negative consequences (e.g., emergence of resistant organisms in the patient herself).

It is true that this sets up a “tragedy of the commons” problem in which antibiotic resistance may emerge and harm other patients. It is frequently asserted that physicians therefore also have an ethical duty to limit antibiotic use to reduce the development of resistance at a local or ecological level.

This is based on tenuous and indirect reasoning that tends to reduce the primacy of the physician’s primary duty to the patient.

If the indications to select, start, and stop antibiotics were so clear-cut as to eliminate the need for physician judgment, this framework might have strong plausibility. However, they aren’t, and it doesn’t.

A physician’s duty to her patient outweighs any hypothesized duty to “society” to such an overwhelming degree that the goal of reducing the emergence of local or wider antibiotic resistance should not influence prescribing decisions in practical terms.

When narrowing or stopping antibiotics is determined to be in the patient’s interests, this should be done, and the resulting reduction in selective pressure for resistance is a welcome secondary outcome. But physicians have no duty to attempt to reduce antibiotic resistance, and to assert or believe otherwise risks distracting from their primary duty to the patient.

“Overuse” of Antibiotics May Have Hidden Benefits

Early indiscriminate use of broad-spectrum antibiotics in mechanically ventilated patients appears to reduce the risk of subsequent systemic infections, and possibly mortality, by reducing the bacterial load in the digestive system.

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This is not an endorsement of that approach, but rather a recognition of the fact that bacterial ecology and the emergence of nosocomial infections are complex phenomena that do not necessarily hew to stewardship policies or conventional medical practice.

Almost certainly, one of the largest causes of sepsis death prior to the turn of the twenty-first century (and possibly still today) has been medical educators’ inculcation of a dangerous antimicrobial conservatism for acutely ill patients. This culturally transmitted teaching is epitomized by the pushback phrase invoked by thousands of residents (including myself) treating hundreds of thousands of patients deteriorating from occult infection over decades: “But I don’t know what I’m treating!”

The answer to that question is easy: you’re treating sepsis. Empirically. Until at least Tuesday.

Clinical Uncertainty Begets Ethical Uncertainty

Roughly half of presumptive infections are uncorroborated by positive cultures. Patients with simmering infections often have clinically ambiguous manifestations, while many uninfected patients have positive “sepsis criteria” by whichever rubric prevails contemporaneously and locally.

In this morass of endemic uncertainty, no one knows the ideal duration of empiric antibiotics for any particular patient. An honest physician feels doubtful and unsure, and is thus more susceptible to influence by a colleague (or internal voice) urging antibiotic discontinuation that may or may not be in a patient’s interest.

Intuition seems too thin a justification, but in many cases, subjective clinical impression is all we have, and may well be the best discriminator available.

But Okay, Yes, Fine. We Do Overprescribe Antibiotics

While the use of broad-spectrum antibiotics is almost always justifiable in the first 24 or 48 hours of critical illness, even if (let’s say) the risk of infection is only 5-10%, their extended use can be wasteful or outright harmful.

By the principle of parsimony and avoidance of adverse effects, antibiotics should be narrowed, limited, and stopped as soon as this is appropriate.

Doing so will also incidentally serve the common good by limiting antibiotic exposure overall.

Antibiotic Stewardship Is A Good Thing, When Someone Else Does It

Reminders and respectful dialogue initiated by a designated colleage (e.g., a pharmacist or stewardship committee representative) can be excellent methods to bring a physician’s cognitive focus to the ideal antibiotic course for a particular patient, avoiding unhelpful extended durations that result from inattention or “autopilot”.

Is There A Practical Framework For This?

Numerous observational and some randomized trials have attempted to establish a method for safely narrowing and stopping antibiotics in the ICU.

This post was originally conceived to detail some of those, and we’ll get to them, but these other issues seemed important to emphasize first.

The TL;DR, though, is that owing to the practical and ethical necessities of trial design, along with the related issue of protean clinical variability among patients and their infections, no heuristic or algorithm can or should replace clinical judgment in antibiotic “de-escalation.”

Conclusions

Because of the co-prevalence of life-threatening illness and occult infection in the ICU, intensivists prescribe broad-spectrum antibiotics to more patients for longer periods than is strictly necessary or beneficial.

There may be effective methods of reducing total antibiotic exposure in the ICU without putting patients at risk, and a future post will address some of those.

But first, it’s important to know who you are taking care of: the patient in the bed in front of you, not imaginary others.

To remember who is responsible for forming a thoughtful care plan for a potential infection: you, not the hospital or its antibiotic stewardship committee.

And to feel the confidence—or its appropriate absence—arising from the fact that no method has been shown to be better than your own best clinical judgment.

Armed with that knowledge, using the available tools—while recognizing their particular advantages and and limitations—will become more coherent and purposeful.

Like everything else we do, it’s about the patient.