| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Guest Access | Sign In via User Name/Password
|
|
|
|||||||
Guest Access | Sign In via User Name/Password |
|||||||||
Springfield, MA
Dr. Brown is Chief, Infectious Disease Division, Baystate Medical Center, Springfield; and Professor of Medicine, Tufts University School of Medicine, Boston, MA.
Correspondence to: Richard B. Brown, MD, FCCP, Chief, Infectious Disease Division, Baystate Medical Center, 759 Chestnut St, Springfield, MA 01107; e-mail: richard.brown{at}bhs.org
It has been almost 2 decades since landmark studies demonstrated the presence and importance of a previously undescribed organism causing pneumonia.12 Within several years the etiology, epidemiology, diagnosis, and treatment became better understood, and the importance of species of Legionella other than Legionella pneumophila became recognized. Coincident with this was the demonstration of Legionella in clinical situations other than community-acquired lower respiratory infection. It became appreciated as a cause of nosocomial pneumonia,3 and became associated with illness outside of the lower respiratory system that included but were not limited to surgical site infections, pericarditis, and intraocular infection.4
Pneumonia continues to be the most common and important manifestation of infection with Legionella. Historically, pneumonia caused by this organism was generally considered to be moderate to severe, with mortality 10 to 15%, and higher if appropriate therapy was delayed.5 Reasons for this degree of severity remain incompletely understood, but are likely to include the following: (1) testing only in patients hospitalized with serious illness, and (2) the increasingly recognized feature of legionellosis coexisting with other bacteria (eg, Streptococcus pneumoniae) independently associated with substantial morbidity and mortality.67
Yu and colleagues (see page 2135) have identified 97 persons (4% of total) meeting laboratory and clinical criteria for Legionella pneumonia through a pharmaceutical database of patients enrolled in six prospective trials for community-acquired pneumonia (CAP). Although study designs varied among the trials, patients identified with legionellosis met criteria for pneumonia and demonstration by either culture or serology for this pathogen. Levofloxacin was investigated in therapy against a variety of comparators. Dose, route, and duration of treatment varied among studies. That levofloxacin was effective in treatment of legionellosis is not surprising, and should not be considered the major importance of their article. Newer fluoroquinolones have long been recognized as effective agents for this disease, and are generally considered one of the antimicrobials of choice because of excellent in vitro and clinical activity, ease of administration, IV and oral bioequivalence, and activity against most other CAP pathogens.8 What becomes more appealing about this investigation is that one third of patients were young and did not have expected comorbidities generally associated with Legionella pneumonia. Additionally, almost two thirds had mild-to-moderate disease, and mortality in the entire population of patients with Legionella treated with levofloxacin was nil. This reinforces recommendations in most CAP guidelines89 to employ agents in outpatients that include activity against "atypical" pathogens (historically anticipated to be Mycoplasma pneumoniae or Chlamydia pneumoniae).
The above commentary is similar to what has been the case with pneumococcal pneumonia, where the spectrum includes severities from mild (eg, "walking pneumonia") to overwhelming. And while there may be an anticipated cadre "typical" for disease, it is well appreciated that it occurs in patients of all ages, and in those without obvious comorbidities. Also similar to pneumococcal pneumonia is the appreciation that we can often treat with shorter antibiotic courses than was generally appreciated and what has been historically recommended. The current investigation, on account of protocols not specifically aimed at therapy for legionellosis, utilized durations of treatment as little as 5 days with generally excellent outcomes, although numbers are small. Indeed, almost 20% of patients were treated with this short duration, similar to recommendations for management of uncomplicated pneumococcal pneumonia in patients with good initial response.8 Recently, other data have demonstrated the effectiveness of azithromycin in 25 patients hospitalized with CAP caused by L pneumophila.10 Mean duration of IV plus oral therapy was < 8 days, with good outcomes. Although the pharmacokinetics and pharmacodynamics of azithromycin are dissimilar to those of the fluoroquinolones, this report adds further substance to the concept of shortened therapy for this disease.
It would have been valuable for Yu and colleagues to have analyzed pooled information about legionellosis in the control populations from the databases that were investigated. As an example in one of these studies, two thirds of a small number of patients with Legionella pneumonia had satisfactory outcomes despite receiving only cephalosporins.11 An analysis of larger numbers of similar patients could have helped place the results of the current study in better perspective, and perhaps provided further information about the natural history of this infection.
Footnotes
The author is on speakers bureaus for Ortho McNeil and Pfizer Pharmaceuticals.
References
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
