Question 22

What are possible reasons for the regional differences in prevalence of ABECOPD pathogens?

The ABECOPD study in Asia provides dramatic results, but these also need to be interpreted carefully due to the relatively small sample size, with 100 or fewer isolates from each of the sites. It may be that the bacterial ecology is different between these sites but another possible reason influencing these results may be the availability of over-the-counter antibiotics. This may result in patients self-medicating for a few days until they improve, without eradicating the original pathogen, ultimately leading to bacteria such as K. pneumoniae and P. aeruginosa suppressing more normal respiratory pathogens and allowing Gram-negatives to predominate. Another possibility relates to the study design. It may be that the study in some centers included a different subgroup of patients, perhaps sicker subjects, reflecting a greater use of inpatient data, leading to bias.