Antagonism between penicillin and erythromycin against Streptococcus pneumoniae: does it exist?

Does radiographic evidence of prior pulmonary tubercular infection influence the choice of empiric antibiotics for community-acquired pneumonia in a tuberculosis-endemic area?

BACKGROUND/PURPOSE

Recent medical literature suggests that use of fluoroquinolones (FQs) might be associated with the delayed diagnosis of pulmonary tuberculosis (TB). The purpose of this study was to assess the impact of radiographic evidence of prior pulmonary TB infection on empiric antibiotic choice in cases of community-acquired pneumonia (CAP), as well as the effect of antibiotic regimens on clinical outcome.

METHODS

A total of 280 patients with CAP between 1 May and 31 December 2007 were included in the study and their medical records were retrospectively reviewed. Patients were divided into two groups: those receiving FQs (FQ group) or those receiving β-lactam-based regimens (β-lactam group). Their demographic data, underlying diseases, clinical features, diseases severity and outcomes were compared.

RESULTS

Radiographic evidence of a previous pulmonary TB infection (odds ratio = 3.507, 95% confidence interval = 1.422-8.645; p = 0.006) was an independent factor associated with β-lactam-based regimens. Patients with a modified pneumonia severity index (mPSI) category V were more likely to receive FQ therapy (odds ratio = 2.53, 95% confidence interval = 1.140-5.615; p = 0.022). Of the patients with mPSI category V, the 14-day mortality rate of those in the β-lactam group was significantly lower than that of those in the FQ group (0%vs. 23%, respectively; p = 0.044).

CONCLUSION

Radiographic evidence of a previous pulmonary TB infection and a lower mPSI score increases the probability of the selection of a β-lactam-based regimen for the treatment of CAP.

Comparison of beta-lactam and macrolide combination therapy versus fluoroquinolone monotherapy in hospitalized Veterans Affairs patients with community-acquired pneumonia

Data comparing the treatment outcomes of the two most frequently recommended empirical antibiotic regimens for community-acquired pneumonia (CAP)--combination therapy with an extended-spectrum beta-lactam and a macrolide (BL+M) or fluoroquinolone (F) monotherapy--for patients with severe CAP are sparse. The purpose of this study was to compare empirical BL+M combination therapy with F monotherapy for Veterans Affairs (VA) patients with severe CAP. This retrospective study included patients with CAP who received empirical therapy with BL+M or F between October 1999 and May 2003 in the Upstate New York VA Network. Outcome measures were 14-day mortality, 30-day mortality, and length of hospital stay (LOS). Severe CAP was defined as a class V pneumonia severity index (PSI). During the study period, 261 patients received BL+M and 254 received F. Disease severity was similar for the two treatment groups at admission, and the presence of tachycardia was the only difference noted. For PSI class V patients, there were lower 14-day and 30-day mortality rates with BL+M than with F (14-day rates, 8.2% versus 26.8% [P = 0.02]; 30-day rates, 18.4% versus 36.6% [P = 0.05]). No differences in mortality between treatment groups were noted for the lower PSI classes. The overall median LOS was significantly longer for the BL+M combination group than for the F monotherapy group (6.0 days versus 5.0 days, respectively [P = 0.01]), but no difference in LOS was noted among PSI class V patients. Our study showed that improved outcomes may be realized with BL+M in cases of severe CAP. A randomized clinical study is warranted based on these results.

Monotherapy versus combination antimicrobial therapy for pneumococcal pneumonia

PURPOSE OF REVIEW

In the past 5 years a number of studies have suggested that combination antibiotic therapy may be superior to monotherapy for pneumococcal pneumonia. This review outlines the major findings for and against combination therapy.

RECENT FINDINGS

The evidence for a benefit of multiple antibiotics is strongest in patients with severe, bacteremic pneumococcal disease. All of these studies have limitations due to their retrospective or uncontrolled design. Unfortunately prospective, randomized, double-blind, controlled studies have not been performed in an appropriately severe disease cohort and are therefore urgently needed. Several viable mechanisms for a benefit of combination therapy have been proposed, especially related to non-antibiotic effects of macrolides. There is also some evidence that third-generation cephalosporins may be superior to penicillins as the non-macrolide component of combination therapy.

SUMMARY

Although based on retrospective and observational data, there is substantial evidence to support combination antibiotic therapy, at least in patients with severe bacteremic pneumococcal pneumonia. What evidence is available supports a cephalosporin/macrolide combination as being associated with the highest survival, but proper prospective studies in patients with severe pneumonia are urgently required to clarify this issue.