ABSTRACT
Background: Four million people die each year from diseases caused by exposure to household air pollution. There is an association between exposure to household air pollution and pneumonia in children (half a million attributable deaths a year); however, whether this is true in adults is unknown. We conducted a case-control study in urban Malawi to examine the association between exposure to household air pollution and pneumonia in adults. Methods: Hospitalized patients with radiologically confirmed pneumonia (cases) and healthy community controls underwent 48 hours of ambulatory and household particulate matter (µg/m 3) and carbon monoxide (ppm) exposure monitoring. Multivariate logistic regression, stratified by HIV status, explored associations between these and other potential risk factors with pneumonia. Results: 145 (117 HIV-positive; 28 HIV-negative) cases and 253 (169 HIV-positive; 84 HIV-negative) controls completed follow up. We found no evidence of association between household air pollution exposure and pneumonia in HIV-positive (e.g. ambulatory particulate matter adjusted odds ratio [aOR] 1.00 [95% CI 1.00-1.01, p=0.141]) or HIV-negative (e.g. ambulatory particulate matter aOR 1.00 [95% CI 0.99-1.01, p=0.872]) participants. Chronic respiratory disease was associated with pneumonia in both HIV-positive (aOR 28.07 [95% CI 9.29-84.83, p<0.001]) and HIV-negative (aOR 104.27 [95% CI 12.86-852.35, p<0.001]) participants. Conclusions: We found no evidence that exposure to household air pollution is associated with pneumonia in Malawian adults. In contrast, chronic respiratory disease was strongly associated with pneumonia.
ABSTRACT
BACKGROUND: The hallmark of non-cystic fibrosis bronchiectasis is recurrent bronchial infection, yet there are significant gaps in our understanding of pathogen persistence, resistance and exacerbation frequencies. Pseudomonas aeruginosa is a key pathogen thought to be a marker of disease severity and progression, yet little is known if the infection risk is seen in those with milder disease or if there is any potential for eradication. These data are important in determining risk stratification and follow up. METHODS AND PATIENT COHORT: A retrospective review of consecutive adult patients attending a specialist UK bronchiectasis clinic over a two-year recruitment period between July 2007 and June 2009 was performed. Analysis of our primary outcome, longitudinal microbiological status, was recorded based on routine clinical follow-up through to data capture point or date of death. Patients were stratified by lung function and infecting organism. RESULTS: 155 patients (mean (SD) age 62.2 (12.4) years; 60.1% female) were identified from clinic records with microbiological data for a median (IQR) follow up duration of 46 (35-62) months. Baseline mean FEV1% predicted was 60.6% (24.8) with mean exacerbation frequency of 4.42/year; 73.6% reported 3 or more exacerbations/year. Haemophilus influenzae was isolated in 90 (58.1%) patients and P. aeruginosa in 78 (50.3%) patients with persistent infection in 51 (56.7%) H. influenzae and 47 (60.3%) P. aeruginosa, respectively. Of the P. aeruginosa colonised patients, 16 (34%) became culture negative on follow-up with a mean of 5.2 negative sputum cultures/patient. P. aeruginosa was isolated from 5 out of 39 patients (12.8%) with minimal airflow limitation as compared to 18 out of 38 patients (47.4%) with severe airflow limitation. Although hospital admissions were significantly higher in the P. aeruginosa infected group (1.3 vs. 0.7 admissions per annum, p = 0.035), overall exacerbation rates were the same (4.6 vs. 4.3, p = 0.58). Independent predictors of P. aeruginosa colonisation were low FEV1% predicted (OR 2.46; 95% CI 1.27-4.77) and polymicrobial colonisation (OR 4.07; 95% CI 1.56-10.58). 17 (11%) patients were infected with multi-resistant strains; however, none were pan-resistant. CONCLUSIONS: P. aeruginosa is associated with greater persistent infection rates and more hospital admissions than H. influenzae. Exacerbation rates, however, were similar; therefore H. influenzae causes significant out-patient morbidity. P. aeruginosa infection occurs across all strata of lung function impairment but is infrequently multi-resistant in bronchiectasis. Careful microbiology follow up is required even in those with well-preserved lung function.
