Bacterial Virulence || Two Important Bacterial Pathogens Causing Community Acquired Pneumonia:Streptococcus pneumoniae andLegionella pneumophila
✍ Scribed by Sansonetti, Philippe
- Publisher
- Wiley-VCH Verlag GmbH & Co. KGaA
- Year
- 2010
- Weight
- 213 KB
- Edition
- 1
- Category
- Article
- ISBN
- 3527323260
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✦ Synopsis
Acute lower respiratory tract infection s ( ARI ) are the leading cause of morbidity and mortality worldwide among infectious diseases. They remain one of the main causes of childhood mortality in the world with an estimated 1 to 1.5 million deaths among children under the age of 5 years, of which the predominant number of cases are due to pneumonia. Community acquired pneumonia , CAP , is defi ned as an infection of the pulmonary parenchyma associated with at least some symptoms/signs of acute infection as well as the presence of acute infi ltrates on chest radiographs in patients that have not been hospitalized 2 weeks prior to the onset of symptoms [1] . It is estimated that 5 -6 million people acquire CAP every year in the USA and about 1 million are hospitalized. Many studies have been carried out to study the etiology of CAP and most studies show that the major causative agent is the bacterium Streptococcus pneumoniae or pneumococci. Other so -called ' typical bacteria ' that cause CAP are Haemophilus infl uenzae and Moraxella catarrhalis. Bacteria including Mycoplasma pneumoniae , Chlamydia spp, and Legionella spp can also be the causative agents of CAP and are traditionally known as atypical bacteria because they differ both clinically and microbiologically from the typical species. Streptococcus pneumoniae is also the most common cause of CAP in hospitalized patients and in fatal cases, whereas Legionella is a common cause of severe CAP requiring admission to intensive care units [2] . However, diagnosis of CAP is not trivial and even though several different methods are in use only a proportion of CAP cases are etiologically diagnosed. Typical symptoms of CAP include for example productive cough, dyspnoea, pleuritic chest pains, fever, tachypnea and tachycardia. However, elderly patients in particular, may not present with all these symptoms and may also report non -respiratory symptoms such as headache, fatigue etc. as the main clinical manifestations.
The type of groups at risk for acquiring CAP depends on the etiological agent to some extent. In the case of pneumococcal pneumonia, small children, especially those below the age of 2 years, and the elderly as well as immuno -compromised