Vidyya Medical News Service
Volume 6 Issue 215 Published - 14:00 UTC 08:00 EST 2-Aug-2004 Next Update - 14:00 UTC 08:00 EST 3-Aug-2004
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H. influenzae bacteria present even after negative cultures from sputum of chronic obstructive disease patients

Haemophilus influenzae, an important bacterial cause of lower respiratory infections that results in exacerbations of chronic obstructive pulmonary disease (COPD), is present far more often in the respiratory tract of adults with COPD than is apparent on the basis of sputum cultures.

Investigators studied isolates of H. influenzae collected monthly over a 7-year period from 104 patients between March 1994 and December 2000. Within this period, the investigators found 122 instances of a gap of 1 month or more of negative cultures followed by isolation of an apparently identical strain of H. influenzae.

Seventeen such episodes lasting 6 months or more were studied in detail to test the hypothesis that these periods of negative cultures actually represented continuous colonization of the lungs by the same strain of H. influenzae in the COPD patients.

The authors said that molecular typing by three independent methods established that the strain preceding and following the episodes of negative cultures were indeed identical.

Also, strain-specific H. influenzae DNA was detected in some of the sputum samples that yielded negative cultures.

The authors said that their results indicate that some patients with COPD are persistently colonized with H. influenzae and that sputum cultures underestimate the frequency of colonization of the respiratory tract by H. influenzae in COPD.

The research is published in the first issue for August 2004 of the American Journal of Respiratory and Critical Care Medicine.

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