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Correspondence |

Interpretation of the Findings of a Cohort Study of Bacteremic Patients With Community-Acquired PneumoniaResponse FREE TO VIEW

Konstantinos Z. Vardakas, MD; Matthew E. Falagas, MD, MSc, DSc
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Affiliations: Alfa Institute of Biomedical Sciences, Athens, Greece,  University of Connecticut School of Medicine, Farmington, CT

Correspondence to: Matthew E. Falagas, MD, MSc, DSc, Alfa Institute of Biomedical Sciences, 9 Neapoleos St, 15123 Marousi, Athens, Greece; e-mail: m.falagas@aibs.gr



Chest. 2007;132(5):1715-1716. doi:10.1378/chest.07-0933
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Metersky et al1concluded in their recently published study that the initial treatment of patients with bacteremic community-acquired pneumonia (CAP) with a macrolide was associated with lower mortality compared to treatment without coverage for atypical microorganisms. Macrolide combination therapy was associated with lower mortality in several other cohort studies23 of bacteremic CAP patients. However, we believe that there are a few issues that should be taken into account regarding the findings of the study by Metersky et al.1 First, as shown in Table 3,1 patients who received antibiotics covering atypical pathogens were more likely (p < 0.001) to have received concordant antibiotic therapy within the first 24 h from hospital admission, which is thought to be associated with lower mortality4; concordant antibiotic therapy was defined as therapy including antibiotics to which the infecting organism was susceptible based on the in vitro susceptibility testing. Second, they were more likely to have received antibiotic therapy within 8 h from hospital admission (p < 0.001), which was also thought to be associated with lower mortality.,4 Third, they were less likely to have been admitted to the hospital from a nursing facility (p < 0.001), which may suggest that their general health status was better. Moreover, the two groups of patients had similar pneumonia severity index (PSI) scores I-IV, while PSI score V patients were fewer in the group of patients who received therapy with atypical pathogen coverage (p = 0.003); PSI score V patients are those with the highest mortality. Although the authors do state that severity of illness and concordant antibiotic therapy were predictors of outcome, they may comment further on the fact that patients receiving atypical pathogen coverage had an advantage on several issues. Thus, the authors may want to discuss the potential effect of various confounding factors.

Metersky et al1 also stated that treatment of bacteremic CAP patients with macrolides but not with fluoroquinolones was associated with lower mortality. This would have been a very interesting finding if the characteristics of patients who received either antibiotic regimen were presented and compared in a table. Since this was not a randomized study, it should not be taken for granted that the characteristics of the included groups of patients were similar. In a study that included patients with CAP (no information regarding bacteremic status was given), Brown et al5 reported that macrolide administration was associated with lower mortality than fluoroquinolone administration, but they acknowledged that patients receiving a macrolide had milder forms of pneumonia. Thus, Metersky et al1 may want to report some additional data on this clinically important issue. Finally, another interesting comparison would be between patients receiving combination therapy with a β-lactam and a macrolide against monotherapy with a fluoroquinolone or combination of a fluoroquinolone with a macrolide, for which the authors may not have available data from this study.1

The authors have no conflicts of interest to disclose.

The author has no conflict of interest to disclose.

Metersky, ML, Ma, A, Houck, PM, et al (2007) Antibiotics for bacteremic pneumonia: improved outcomes with macrolides but not with fluoroquinolones.Chest131,466-473. [PubMed] [CrossRef]
 
Baddour, LM, Yu, VL, Klugman, KP, et al Combination antibiotic therapy lowers mortality among severely ill patient with pneumococcal bacteremia.Am J Respir Crit Care Med2004;170,440-444. [PubMed]
 
Waterer, GW, Somes, GW, Wunderink, RG Monotherapy may be suboptimal for severe bacteremic pneumococcal pneumonia.Arch Intern Med2001;161,1837-1842. [PubMed]
 
Mandel, LA, Wunderink, RG, Azueto, A, et al Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults.Clin Infect Dis2007;44,S27-S72. [PubMed]
 
Brown, RB, Iannini, P, Gross, P, et al Impact of initial antibiotic choice on clinical outcomes in community-acquired pneumonia: analysis of a hospital claims-made database.Chest2003;123,1503-1511. [PubMed]
 
To the Editor:

We wish to thank Drs. Vardakas and Valagas for their interest in our article1 (February 2007). They are correct that there were significant differences between patients receiving treatment covering atypical organisms and those who did not. While these differences were adjusted for in the multivariate analysis, there is the possibility that there were important differences between the patient populations that were not accounted for in the analysis. We acknowledge that this may also be true for the comparison of macrolide vs fluoroquinolone treatment. Ideally, nonrandomized studies like ours are best used to frame important research questions, not to provide definitive answers. This is why we stated in the concluding paragraph of our article that randomized trials are needed to answer the questions generated by our study.

References
Metersky, MI, Ma, A, Houck, PM, et al Antibiotics for bacteremic pneumonia: improved outcomes with macrolides but not fluoroquinolones.Chest2007;131,466-473. [PubMed] [CrossRef]
 

Figures

Tables

References

Metersky, ML, Ma, A, Houck, PM, et al (2007) Antibiotics for bacteremic pneumonia: improved outcomes with macrolides but not with fluoroquinolones.Chest131,466-473. [PubMed] [CrossRef]
 
Baddour, LM, Yu, VL, Klugman, KP, et al Combination antibiotic therapy lowers mortality among severely ill patient with pneumococcal bacteremia.Am J Respir Crit Care Med2004;170,440-444. [PubMed]
 
Waterer, GW, Somes, GW, Wunderink, RG Monotherapy may be suboptimal for severe bacteremic pneumococcal pneumonia.Arch Intern Med2001;161,1837-1842. [PubMed]
 
Mandel, LA, Wunderink, RG, Azueto, A, et al Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults.Clin Infect Dis2007;44,S27-S72. [PubMed]
 
Brown, RB, Iannini, P, Gross, P, et al Impact of initial antibiotic choice on clinical outcomes in community-acquired pneumonia: analysis of a hospital claims-made database.Chest2003;123,1503-1511. [PubMed]
 
Metersky, MI, Ma, A, Houck, PM, et al Antibiotics for bacteremic pneumonia: improved outcomes with macrolides but not fluoroquinolones.Chest2007;131,466-473. [PubMed] [CrossRef]
 
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