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Efficacy of Tigecycline Compared to Levofloxacin for Treating Streptococcus Pneumoniae Bacteraemia in Patients With Community-Acquired Pneumonia: Presented at ECCMID-ICC

By Chris Berrie

MUNICH, GERMANY -- April 5, 2007 -- The first-in-class glycylcycline agent, tigecycline, appears safe and shows a clinical cure rate that is similar to the fluoroquinolone levofloxacin in hospitalised patients with community-acquired pneumonia (CAP), according to results from a combined analysis from 2 multicentre, double-blind, randomised phase 3 studies.

Further, in the patients with CAP and Streptococcus pneumoniae bacteraemia, tigecycline achieved clinical cure rates similar to those seen in tigecycline-treated patients without bacteraemia, a researcher reported here at the joint 17^th European Congress of Clinical Microbiology and Infectious Diseases and 25^th International Congress on Chemotherapy (ECCMID-ICC).

Natalie Dartois, MD, study medical monitor and director, infectious diseases and cardiovascular metabolism, Wyeth Research, Paris, France, presented the results on April 1^st.

"Tigecycline has been registered for patients with complicated skin/skin structure infection and intra-abdominal infection, and so we have continued with the lung as we know it has good tissue penetration," Dr. Dartois said.

Similarly, as CAP is ranked the fourth most common cause of death in the United Kingdom, and S. pneumoniae the most commonly encountered cause of CAP in both the outpatient and inpatient settings, tigecycline appears a promising agent for the targeting of pneumonia pathogens.

Patients with CAP who exhibit S. pneumoniae bacteraemia frequently have more severe disease and increased mortality rates than those with CAP without bacteraemia. Therefore, these 2 studies were designed to compare the efficacy and safety of tigecycline and levofloxacin in a subset of hospitalised patients with CAP with and without pneumococcal bacteraemia.

The main inclusion criteria were age 18 years or more, hospitalisation with CAP, and intravenous antibiotic treatment. Patients had to have at least 2 other indicated symptoms associated with CAP. A standard series of exclusion criteria also needed to be satisfied.

Following randomisation, the tigecycline group received an IV dose of 100 mg, and then 50 mg IV every 12 hours. The levofloxacin group received an IV dose of 500 mg either every 12 or 24 h.

The clinical response in these patients was evaluated as the test-of-cure (TOC), 7 to 23 days after therapy was completed. Clinical cure criteria were the following: improvement or resolution of all signs and symptoms of pneumonia present at enrolment; chest radiographs not worsened; no further need for treatment of pneumonia; no worsening or reappearance of new signs or symptoms.

In the 2 studies combined, 846 patients received at least 1 dose of study drug, and the results were presented for both the microbiologically evaluable (ME; n = 345) and the microbiological modified intent-to-treat population (m-mITT; n = 457). For the former, 11.6% had S. pneumoniae bacteraemia, with the equivalent in the m-mITT population showing at 10.9% of patients.

For the m-mITT patient population with pneumococcal bacteraemia, tigecycline satisfied the clinical cure criteria in 81.5% of 27 cases, as compared with levofloxacin at 65.2%.

In comparison, the m-mITT patient population without pneumococcal bacteraemia achieved cure rates of 85.7% in 189 patients and 87.2% of 203, respectively. Therefore, with the tigecycline treatment only, the cure rate of the bacteraemia patient population was similar to that for the non-bacteraemia patient population.

The researchers also noted that the minimum inhibitory concentrations (MICs) for tigecycline and levofloxacin for S. pneumoniae blood isolates ranged were 0.03-0.12 microg/mL and 0.5-1.0 microg/mL, respectively.

Respective rates of discontinuations due to adverse events in the 2 treatment groups were 6.1% and 8.3%; the safety data from these 2 combined studies was similar between tigecycline and levofloxacin, Dr. Dartois said.

Overall, tigecycline and levofloxacin appeared safe and achieved similar cure rates in these hospitalised patients with CAP, she said.

For the S. pneumoniae bacteraemia subset, however, Dr. Dartois noted, "We can see that with tigecycline there is a very good cure rate even in the bacteraemia patients, and this is really important and interesting because we know that the serum level of tigecycline is high. So it is very good to know that we had some good results in these patients."

Levofloxacin did not achieve these results in bacteraemia patients, she added, which suggests that empiric tigecycline may be a preferable treatment option for these hospitalised patients with CAP who require intravenous antibiotic therapy.

This study was supported by an educational/research grant from Wyeth.


[Presentation title: Efficacy of Tigecycline (TGC) Compared to Levofloxacin (LEV) for Treating Streptococcus Pneumoniae Bacteraemia in Patients (Pts) Hospitalised With Community-Acquired Pneumonia (CAP). Abstract P848]

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