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.

Rationale: In the context of rapid antiretroviral therapy rollout and an increasing burden of noncommunicable diseases, there are few contemporary data describing the etiology and outcome of community-acquired pneumonia (CAP) in sub-Saharan Africa. Objectives: To describe the current etiology of CAP in Malawi and identify risk factors for mortality. Methods: We conducted a prospective observational study of adults hospitalized with CAP to a teaching hospital in Blantyre, Malawi. Etiology was defined by blood culture, Streptococcus pneumoniae urinary antigen detection, sputum mycobacterial culture and Xpert MTB/RIF, and nasopharyngeal aspirate multiplex PCR. Measurements and Main Results: In 459 patients (285 [62.1%] males; median age, 34.7 [interquartile range, 29.4–41.9] yr), 30-day mortality was 14.6% (64/439) and associated with male sex (adjusted odds ratio, 2.60 [95% confidence interval, 1.17–5.78]), symptom duration greater than 7 days (2.78 [1.40–5.54]), tachycardia (2.99 [1.48–6.06]), hypoxemia (4.40 [2.03–9.51]), and inability to stand (3.59 [1.72–7.50]). HIV was common (355/453; 78.4%), frequently newly diagnosed (124/355; 34.9%), but not associated with mortality. S. pneumoniae (98/458; 21.4%) and Mycobacterium tuberculosis (75/326; 23.0%) were the most frequently identified pathogens. Viral infection occurred in 32.6% (148/454) with influenza (40/454; 8.8%) most common. Bacterial–viral coinfection occurred in 9.1% (28/307). Detection of M. tuberculosis was associated with mortality (adjusted odds ratio, 2.44 [1.19–5.01]). Conclusions: In the antiretroviral therapy era, CAP in Malawi remains predominantly HIV associated, with a large proportion attributable to potentially vaccine-preventable pathogens. Strategies to increase early detection and treatment of tuberculosis and improve supportive care, in particular the correction of hypoxemia, should be evaluated in clinical trials to address CAP-associated mortality.

BackgroundChronic airway infection contributes to the underlying pathogenesis of non-cystic fibrosis bronchiectasis (NCFBr). In contrast to other chronic airway infections, associated with COPD and CF bronchiectasis, where polymicrobial communities have been implicated in lung damage due to the vicious circle of recurrent bacterial infections and inflammation, there is sparse information on the composition of bacterial communities in NCFBr. Seventy consecutive patients were recruited from an outpatient adult NCFBr clinic. Bacterial communities in sputum samples were analysed by culture and pyrosequencing approaches. Bacterial sequences were analysed using partial least square discrimination analyses to investigate trends in community composition and identify those taxa that contribute most to community variation.ResultsThe lower airway in NCFBr is dominated by three bacterial taxa Pasteurellaceae, Streptococcaceae and Pseudomonadaceae. Moreover, the bacterial community is much more diverse than indicated by culture and contains significant numbers of other genera including anaerobic Prevotellaceae, Veillonellaceae and Actinomycetaceae. We found particular taxa are correlated with different clinical states, 27 taxa were associated with acute exacerbations, whereas 11 taxa correlated with stable clinical states. We were unable to demonstrate a significant effect of antibiotic therapy, gender, or lung function on the diversity of the bacterial community. However, presence of clinically significant culturable taxa; particularly Pseudomonas aeruginosa and Haemophilus influenzae correlated with a significant change in the diversity of the bacterial community in the lung.ConclusionsWe have demonstrated that acute exacerbations, the frequency of exacerbation and episodes of clinical stability are correlated, in some patients, with a significantly different bacterial community structure, that are associated with a presence of particular taxa in the NCFBr lung. Moreover, there appears to be an inverse relationship between the abundance of P. aeruginosa and that of of H. influenzae within the NCFBr lung bacterial community. This interaction requires further exploration.