Determinants of chronic infection with Staphylococcus aureus in patients with bronchiectasis

Abstract

Staphylococcus aureus is an uncommon pathogen in bronchiectasis not caused by cystic fibrosis (CF). The object of this study was to identify characteristics that cause patients to be prone to infection with S. aureus.The study population consisted of patients with bronchiectasis attending the authors' unit, excluding those with a diagnosis of overt CF. All patients had a high resolution computer tomographic scan (HRCT) of the thorax which demonstrated bronchiectasis. Cases that were currently chronically infected with S. aureus (isolated consecutively on more than two occasions >3 months apart) were identified (n=12) and compared with 74 control patients who had not been chronically infected with S. aureus. Patients were carefully evaluated to determine the aetiology of their disease. Odds ratios (OR) and 95% confidence intervals (CI) as measures of the association between disease characteristics and chronic infection with S. aureus were calculated.The results for patients chronically infected by S. aureus demonstrated significant associations with allergic bronchopulmonary aspergillosis (ABPA; OR=8.8, 95% CI 1.8±41.9), atypical variants of CF (OR=12.0, 95% CI 1.8±81.7) or equivocal sweat sodium values (OR=4.0, 95% CI 1.0±15.3). The associations persisted when the analysis was based on cases (n=28) in whom S. aureus had ever been isolated from sputum. In the latter analysis there was also a significant association with predominant upper zone disease on HRCT.These results suggest that patients with bronchiectasis in whom S. aureus is isolated from sputum should be carefully evaluated to exclude allergic bronchopulmonary aspergillosis or atypical cystic fibrosis. Eur Respir J 1999; 14: 1340±1344. Staphylococcus aureus is a gram positive coccus which is only occasionally cultured from the sputum of patients with bronchiectasis [1], whereas in patients with cystic fibrosis (CF) it is almost always the initial bacterial infection [2±4]. In CF S. aureus infection may stimulate an inflammatory response that causes lung damage and facilitates subsequent chronic infection with Pseudomonas aeruginosa [2±4]. Once chronic infection with P. aeruginosa has occurred S. aureus is less frequently cultured and it has been suggested that this is due to anti-staphylococcal factors produced by P. aeruginosa [5]. Several reports of sputum microbiology and bronchoscopic sampling suggest that S. aureus occurs in~4±10% of patients with non-CF bronchiectasis [6±8]. The reason for this difference in the type of bacterial infective organisms is unclear. The object of the present study was to identify common characteristics of a group of patients with non-CF bronchiectasis who were chronically infected with S. aureus. Methods Study definitionsChronic infection with S. aureus was defined as patients who were infected with S. aureus during the study period and the bacterium had been isolated from consecutive sputum samples taken on more than two occasions >3 months apart. Intermittent infection with S. aureus was defined when the ba...

Pulmonary Nontuberculous Mycobacteriosis and Chronic Lower Respiratory Tract Infections in Patients with Allergic Bronchopulmonary Mycosis without Cystic Fibrosis

“…Isolated organisms found in the cLRTIs in the present study were most frequently methicillin-sensitive Staphylococcus aureus, followed by Pseudomonas aeruginosa, E. coli, and others. Isolation of S. aureus is compatible with a previous report that showed an association between S. aureus and ABPM without CF (16). P. aeruginosa, E. coli, and H. influenzae were reported to be isolated from patients with bronchiectasis (14,17), and there is a report of 3 patients with ABPM accompanied by cLRTIs caused by P. aeruginosa (18).…”

Guidelines for the management of adult lower respiratory tract infections

“…[208]. A recent study found an association between Staph aureus in the airways and the presence of allergic bronchopulmonary aspergillosis [230]. Potentially nonpathogenic microorganisms, such as H. parainfluenzae, are also frequently isolated from the sputum.…”

Allergic Bronchopulmonary Aspergillosis in Cystic Fibrosis—State of the Art: Cystic Fibrosis Foundation Consensus Conference

“…Shah et al [276] evaluated patients with bronchiectasis who did not have CF. They found that of those chronically infected with S. aureus (as evidenced by sputum cultures), there was a significant association with ABPA (OR, 8.8).…”