Oral or intravenous-to-oral antibiotic switch therapy for treating patients with community-acquired pneumonia.

In this issue of The American Journal of Medicine, Castro-Guardiola et al. (1) report a study of patients with severe and nonsevere community-acquired pneumonia. The results of the study give additional support to greater use of oral antimicrobial therapy for communityacquired pneumonias. The most common pathogens causing community-acquired pneumonia are bacterial; Streptococcus pneumoniae and Moraxella catarrhalis are responsible for about 85% of cases, whereas about 15% are caused by nonzoonotic atypical organisms, such as Legionella, Mycoplasma pneumoniae, or Chlamydia pneumoniae. Typical pathogens may be differentiated from atypical pathogens on a clinical basis, but most clinicians cover both groups of pathogens with appropriate monotherapy (2). In the study reported in this issue of the Journal, a two-step approach was used, treating patients with betalactam antibiotics initially and adding a macrolide or quinolone if atypical pathogens were suspected (1). Outcomes might have been even better (and less expensive) had the investigators used monotherapy that was effective against both typical and atypical organisms, such as doxycycline or a “respiratory quinolone” (e.g., levofloxacin or gatifloxacin) (3). Monotherapy is as effective as combination therapy and is less complicated and expensive. Moreover, the likelihood of drug side effects and interactions are minimized with monotherapy. Siegel et al. (4) have reported the effectiveness of intravenous-to-oral switch programs for patients with community-acquired pneumonia. They demonstrated that 2 days of parenteral therapy followed by 12 days of oral therapy was equivalent to 14 days of parenteral therapy. Traditionally, physicians have thought that intravenous therapy was preferred to oral antimicrobial therapy. Parenteral antibiotic therapy is necessary for critically ill patients or for those unable to take oral medications. Ideal antibiotics for switch programs are those with a high bioavailability ( 90%) of the same class, such as doxycycline, levofloxacin, gatifloxacin, trimethoprimsulfamethoxazole, linezolid, metronidazole, clindamycin, or chloramphenicol. Some oral antibiotics have no parenteral equivalent, and many parenteral antibiotics, including aminoglycosides, monobactams, and carbapenems, have no oral formulations. There has been some reluctance to use oral switch therapy for patients with severe pneumonia or bacteremic pneumococcal pneumonia. However, pneumococcal bacteremia does not affect response to switch therapy (5,6). The advantages of switch therapy include patient compliance, decreased phlebitis, fewer infections associated with intravenous lines, and shorter length of stay. Oral therapy is always less expensive than equivalent parenteral therapy. Not only is the acquisition cost of oral antibiotics less than that of their parenteral counterparts, but also the costs of the intravenous administration fee are eliminated; for example, levofloxacin costs about $17 for a 500-mg intravenous dose plus about a $10 daily administration cost, whereas the cost of the same dose administered orally is approximately $5.50. Moreover, an early switch to oral antibiotics reduces phlebitis and intravenous-line infections and permits earlier hospital discharge (7,8). Some clinicians have been concerned about the need to observe patients in the hospital after the intravenous-tooral switch. It has been shown, however, that patients may be discharged on an oral therapy regimen as soon as the transition is made if there are no other medical reasons to continue hospitalization (9). Many infectious disease clinicians, including myself, have long used oral therapy for patients with mildly to moderately severe pneumonia. Some would even argue that if oral therapy is used, patients may not need hospital admission. Many patients are admitted for other reasons, however, such as the need for oxygen supplementation or because of comorbid conditions that require care. Thirdparty payers should realize that oral antibiotic therapy is not a contraindication to hospitalization, but is a less expensive yet equally effective way to treat patients. Patients should no longer be treated with intravenous therapy unless they are critically ill or unable to take oral medications. The goal of effective antimicrobial therapy should be to eradicate the infection, which is equally effective with appropriate oral or intravenous antibiotic therapy. This is the era of oral antibiotic therapy. Parenteral antibiotic therapy is essential as initial therapy for critically ill patients with pneumonia or other infectious disAm J Med. 2001;111:412– 413. From the Infectious Disease Division, Winthrop-University Hospital, Mineola, New York; and State University of New York School of Medicine, Stony Brook, New York. Requests for reprints should be addressed to Burke A. Cunha, MD, Infectious Disease Division, Winthrop-University Hospital, Mineola, New York 11501.