The Lean Antibiotic Mantra

Sometimes Nothing Is Better Than Something

Neil Gaffin, MD; Brad Spellberg, MD


April 09, 2018

A major challenge in making an accurate diagnosis of pneumonia is that the causative pathogens are usually not known.[4] In older literature, Streptococcus pneumoniae was by far the most common cause of community-acquired pneumonia. However, multiple recent studies have found that despite extensive testing, 50%-60% of cases of community-acquired pneumonia in the United States lack a definable etiology or are caused by viruses.[6,7,8] This shift to viral pathogens probably reflects a decline in pneumococcal carriage rates in the era of vaccination.

In February 2017, the US Food and Drug Administration approved the blood infection marker procalcitonin for guiding antibiotic therapy in patients with acute respiratory infections. This test has been studied extensively as a biomarker of invasive bacterial respiratory tract infections. If the test is ordered 6-12 hours after the onset of illness, values < 0.5 ng/dL indicate that antibiotics may be safely discontinued (or withheld if they have not been started).

A recent meta-analysis of nearly 7000 patients from 26 studies, conducted in 12 countries, found that incorporating procalcitonin into therapeutic decision-making resulted in an ~30% reduction in duration of antibiotic therapy while reducing antibiotic-related side effects by 32%, and significantly reduced mortality from 10% to 9%.[9] The survival advantage is probably due to avoidance of the harm events that occur from antibiotic exposure, while limiting antibiotic therapy to patients with invasive bacterial infections.

For this patient, the respiratory pathogen test was negative and his procalcitonin result 24 hours later was 0.07 ng/mL (a level < 0.5 ng/mL indicating that antibiotics could be withheld safely). Antibiotic therapy ended, and the patient did well. [9,10]

A Woman With a Painful Left Hand

An 86-year-old woman who resides in a long-term care facility came to the ED with a report of 10 days of progressively worsening redness, swelling, and pain over the dorsum of the left hand after sustaining a fall. There was no history of fever. Amoxicillin/clavulanic acid was started 2 days before the ED visit for possible cellulitis. Her medical history was notable for dementia, rheumatoid arthritis, chronic kidney disease, and diabetes mellitus.

In the ED, the patient was afebrile. The dorsum of the left hand was warm, red, and swollen, particularly over the second metacarpophalangeal joint (Figure 2). The WBC count was 13,000 cells/µL. The BUN and creatinine levels were 101 mg/dL and 2.9 mg/dL, respectively (54 and 1.8 mg/dL the previous month). Hand x-ray revealed no fractures.

The tentative diagnosis was cellulitis and tenosynovitis, and the patient was started on vancomycin and cefazolin in the ED.

Figure 2. The patient's left hand on the day of admission.


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