Bacterial pneumonia

Bacterial pneumonia is a type of pneumonia caused by bacterial infection. Streptococcus pneumoniae () is the most common bacterial cause of pneumonia in all age groups except newborn infants. Streptococcus pneumoniae is a Gram-positive bacterium that often lives in the throat of people who do not have pneumonia. Other important Gram-positive causes of pneumonia are Staphylococcus aureus () and Bacillus anthracis. Gram-negative bacteria are seen less frequently: Haemophilus influenzae (), Klebsiella pneumoniae (), Escherichia coli (), Pseudomonas aeruginosa (), Bordetella pertussis, and Moraxella catarrhalis are the most common. These bacteria often live in the gut and enter the lungs when contents of the gut (such as vomit or faeces) are inhaled. Pneumonia caused by Yersinia pestis is usually called pneumonic plague. Atypical bacteria causing pneumonia are Coxiella burnetii, Chlamydophila pneumoniae (), Mycoplasma pneumoniae (), and Legionella pneumophila. The term "atypical" does not relate to how commonly these organisms cause pneumonia, how well it responds to common antibiotics or how typical the symptoms are; it refers instead to the fact that these organisms have atypical or absent cell wall structures and do not take up Gram stain in the same manner as gram-negative and gram-positive organisms. Pneumonia Fever Rigors Cough Runny nose (either direct bacterial pneumonia or accompanied by primary viral pneumonia) Dyspnea – shortness of breath Chest pain Shaking chills Pneumococcal pneumonia can cause coughing up of blood, or hemoptysis, characteristically associated with "rusty" sputum Bacteria typically enter the lung with inhalation, though they can reach the lung through the bloodstream if other parts of the body are infected. Often, bacteria live in parts of the upper respiratory tract and are continuously being inhaled into the alveoli, the cavities deep in the lungs where gas exchange takes place. Once inside the alveoli, bacteria travel into the spaces between the cells and also between adjacent alveoli through connecting pores.