By Stan Deresinski, MD, FACP

Clinical Professor of Medicine, Stanford University

SYNOPSIS: The CDC and the American College of Physicians have provided advice on the best practice regarding the duration of antibiotic therapy for several common infections.

SOURCE: Lee RA, Centor RM, Humphrey LL, et al. Appropriate use of short-course antibiotics in common infections: Best practice advice from the American College of Physicians. Ann Intern Med 2021; Apr 6. doi: 10.7326/M20-7355. [Online ahead of print].

The CDC and the American College of Physicians have provided best practice advice addressing the duration of antibiotic therapy for several infections commonly encountered in primary care. These include acute bacterial exacerbations of COPD, community-acquired pneumonia, uncomplicated urinary tract infections, and non-purulent cellulitis. Their recommendations:

  • Acute bacterial exacerbations of COPD: five days. The authors refer to this entity as acute bronchitis in adults with COPD and describe clinical signs of bacterial infection. These are listed as “increased sputum purulence in addition to increased dyspnea and/or increased sputum volume.”
  • Community-acquired pneumonia: five days. This recommendation refers to non-immunocompromised adults who achieve clinical stability and follows the Infectious Diseases Society of America/American Thoracic Society guideline.
  • Uncomplicated bacterial cystitis in nonpregnant adult women: nitrofurantoin for five days, trimethoprim-sulfamethoxazole for three days, or fosfomycin as a single dose.
  • Uncomplicated pyelonephritis in nonpregnant adults: depending on susceptibility test results, a fluoroquinolone for five to seven days, or trimethoprim-sulfamethoxazole for 14 days.
  • Non-purulent cellulitis in all adults: an antibiotic active against streptococci for five to six days.


This best practice advisory is useful, but some of its recommendations are perhaps more conservative than necessary. One important example is illustrated by a recently published randomized trial that showed three days of antibiotic therapy was noninferior to eight days in hospitalized patients with moderately severe community-acquired pneumonia who achieved clinical stability after three days of therapy.1 On the other hand, the recommendation for the FDA-approved use of fosfomycin as a single dose may be insufficient in women with uncomplicated lower urinary tract infection, as shown in a recent randomized trial demonstrating this to be significantly less effective than a five-day course of nitrofurantoin.2

This advisory serves as a good starting point in convincing clinicians to shorten unnecessarily prolonged durations of antibiotic therapy, thus reducing the selective pressure leading to the evolution of antimicrobial resistance. However, there is a long way to go. 


  1. Dinh A, Ropers J, Duran C, et al; Pneumonia Short Treatment (PTC) Study Group. Discontinuing β-lactam treatment after 3 days for patients with community-acquired pneumonia in non-critical care wards (PTC): A double-blind, randomised, placebo-controlled, non-inferiority trial. Lancet 2021;397:1195-1203.
  2. Huttner A, Kowalczyk A, Turjeman A, et al. Effect of 5-day nitrofurantoin vs single-dose fosfomycin on clinical resolution of uncomplicated lower urinary tract infection in women: A randomized clinical trial. JAMA 2018;319:1781-1789.