Relationship between the GOLD combined COPD assessment staging system and bacterial isolation

BACKGROUND Acute exacerbations, which are a significant cause of mortality and morbidity, adversely affect chronic obstructive pulmonary disease (COPD) prognosis by accelerating loss of lung function. It is important to know the microorganisms that commonly cause exacerbations in the patient groups classified according to clinical and functional characteristics for fast and accurate treatment of acute exacerbations. OBJECTIVES The last Global Initiative for Chronic Obstructive Lung Disease (GOLD) publication recommended a new staging system containing obstruction degree, frequency of exacerbations, and quality of life questionnaires. This study is designed to analyze the relationship between the bacteria isolated in acute exacerbations and new GOLD stages. METHODS Potentially pathogenic bacteria (PPB) isolation with culture and polymerase chain reaction methods were obtained from 114 acute exacerbation COPD patients, classified into A, B, C, and D groups by analyzing the forced expiratory volume in 1 second (FEV1) value, COPD Assessment Test (CAT) score, and exacerbation frequency according to the new GOLD staging system. RESULTS There was a significant correlation between exacerbation frequency and PPB isolation (P=0.002). There was no relationship between GOLD stage, FEV1, and CAT score with PPB isolation. The isolated bacteria diversity and mixed infection frequency were higher in the GOLD stage D group. Pseudomonas aeruginosa, Escherichia coli, and Acinetobacter baumannii were isolated only from D group patients. CONCLUSION Bacterial infection may cause an acute exacerbation equally in each stage for COPD. The difference in bacterial etiology is more related to exacerbation frequency than FEV1 and CAT scores for an acute exacerbation. Determining exacerbation frequency is significant for treatment success in empirical antibiotic selection.