Bacterial respiratory infections : the global burden of disease and strategies for control

Bacterial infections of the respiratory tract remain a major cause of morbidity and death in both developed and developing countries. Seven microbes are responsible for virtually all bacterial infections: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Pseudomonas aeruginosa, Mycobacterium tuberculosis, Corynebacterium diphtheriae and Bordetella pertussis. All of these microbes establish infection at the site of the respiratory mucosa, however the pathogenesis of disease varies. Some, such as B. pertussis are obligate pathogens whilst others, such as H. influenzae, are commensals of the upper respiratory tract. The burden of disease falls across all age groups - from young children to the elderly. In recent years the widespread use of antibiotics has had a significant impact on limiting serious complications that arisefrom these infections and in reducing mortality, particularly in developed countries. However, increased bacterial resistance to chemotherapy is evident and a major concern for the long-term application of this therapeutic approach. Effective vaccines have been developed for some pneumococcal and haemophilus infections, diphtheria and whooping cough. In developing countries access to these vaccines presents a problem for their widespread and equitable distribution. In developed countries anti-vaccine lobby groups, controversy over the expense of routine scheduling of the pneumococcal vaccine and complacency in the absence of endemic disease are significant frustrations for national immunisation programs. In a review of this nature it is not possible to address all seven bacteria and their clinical manifestations. Instead, otitis media, the most common paediatric illness for which medical advice is sought in the developed world, is provided as a case study. Wherever possible, the review broadens to the global context of infectious diseases and their control.