The microbiology of ABECB potential predictive value of clinical criteria
Abstract number: 1134_02_87
To explore the relationship between specific pulmonary disease severity criteria and the microbiology of acute bacterial exacerbations of chronic bronchitis (ABECB).
This was a double-blind, randomized clinical trial evaluating levofloxacin 750 mg qd for 35 days in ABECB. All potential subjects had to meet the ATS definition of chronic bronchitis but only those patients with Anthonisen type 1 or 2 exacerbations (N = 763) were enrolled. Stratification by disease severity was determined using parameters suggested by Grossman: FEV1 % of predicted value, defined co-morbidities, and number of exacerbations during the previous 12 months. Because different spectra of etiologic organisms were expected on the basis of the stratification, different comparator agents were used for uncomplicated patients (azithromycin for five days) and those considered complicated (amoxicillin/clavulanate for ten days).
Initial microbiology from all intent-to-treat patients revealed notable differences between the two strata. Among isolates from uncomplicated cases, 55% were the traditional triad of S. pneumoniae, H. influenzae, and M. catarrhalis. Inclusion of H. parainfluenzae raises this figure to 79%. In the complicated arm the figures were 48% and 68%, respectively. Gram-negative bacilli, primarily Enterobacteriaceae spp. and several Pseudomonads, represented 15% of the uncomplicated and 23% of the complicated isolates. Microbiological eradication rates and the percentage of organism persisting after therapy from the uncomplicated stratum were compatible with the unexpectedly large number of macrolide-resistant organisms isolated. In the complicated arm, both levofloxacin and amoxicillin/clavulanate had lower, but comparable, eradication and persistence rates. Clinical efficacy in microbiologcally-evaluable patients was consistent with these figures.
While there was clearly overlap among the flora isolated from the two strata defined by application of the Grossman criteria, there was separation of the populations. This predictive approach seems to be of value in identifying the optimal antimicrobial regimen, especially for uncomplicated exacerbations. Further work to define and validate predictive clinical parameters may help optimize the choice and duration of antimicrobial agents for ABECB.
|Session name:||XXIst ISTH Congress|
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